System and method for controlling loudness in an electroacoustic transducer - Patents.com

Abstract

Systems and methods for controlling loudness of an electro-acoustic transducer may include receiving transfer function data elements representing a transfer function between (a) an electrical input and (b) an output sound pressure level (SPL) of the electro-acoustic transducer, applying the transfer function to the incoming electrical signal to obtain an expected SPL signal representing an expected SPL of the electro-acoustic transducer in response to the incoming electrical signal, identifying at least one acoustic fundamental in the expected SPL signal, generating at least one compensation electrical signal corresponding to an acoustic harmonic of the identified at least one acoustic fundamental, and controlling loudness of the electro-acoustic transducer based at least in part on the at least one compensation electrical signal.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 279,128, filed November 14, 2021, entitled "SYSTEM AND METHOD FOR CONTROLLING LOUDNESS OF AN ELECTRO-ACOUND TRANSDUCER," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates generally to loudness enhancement, and more particularly to a loudness enhancer with sound dosimeter for headphones and earphones. [Background technology]

[0003] Listening to music through headphones or earphones for long periods of time and / or at high volumes can cause damage to hearing. Legal regulations have been introduced in many countries to address this risk. Such regulations are detailed, for example, in the IEC 62368-1 and IEC 50332 series of standards. These legal regulations aim to reduce the maximum sound pressure level (SPL) to 100 decibels (dB(A)) in order to protect the listener's hearing.

[0004] When the acoustic dynamics (e.g. loudness differences between different parts of a piece of music) are relatively small, following this standard may result in a satisfactory sensation of loudness. For example, the music production process for pop music usually results in a small dynamic loudness range, allowing a single volume setting throughout the entire listening session. However, music with a large dynamic loudness range (e.g. large loudness differences between different parts of a piece of music), such as classical music, is usually perceived by the listener as not loud enough, at least in the quieter parts of the piece. In such cases, the 100 dB(A) limit may be perceived as too low, leading music lovers to turn up the volume on their headphones.

[0005] Additionally, currently available sound dosimeters (e.g., those described in the IEC 50332-3 standard) may limit the maximum cumulative sound dose for one person using a particular headphone, however, such measures may also limit the sound levels for a second user of the same headphone who has not yet reached the maximum sound dose. Summary of the Invention

[0006] An embodiment of the present invention may include a method of controlling the loudness of an electro-acoustic transducer by at least one processor. The terms "electro-acoustic transducer" and "transducer" may be used interchangeably herein to refer to any electrical device capable of producing sound based on an incoming electrical signal, including, for example, a headphone device, a loudspeaker, an array of loudspeakers, a telephone, etc.

[0007] An embodiment of the method may include receiving a transfer function data element representing a transfer function between (a) an electrical input to an electro-acoustic transducer and (b) an output sound pressure level (SPL) of the electro-acoustic transducer, applying the transfer function to the input electrical signal to obtain an expected SPL frequency graph of the electro-acoustic transducer, identifying at least one acoustic fundamental in the SPL frequency graph, generating a compensation electrical signal corresponding to an acoustic harmonic signal of the identified at least one acoustic fundamental, generating a superimposed signal based on the input electrical signal and the compensation electrical signal, and providing the superimposed signal as an input to the electro-acoustic transducer to control the loudness of the electro-acoustic transducer.

[0008] According to some embodiments, identifying at least one acoustic fundamental in the SPL frequency graph may include segmenting the SPL frequency graph into frequency bands and identifying at least one acoustic fundamental as relating to a particular frequency band of the SPL frequency graph.

[0009] According to some embodiments, generating the compensation electrical signal may include determining one or more acoustic harmonic frequencies of the identified at least one acoustic fundamental based on a particular frequency band of the SPL frequency graph, determining one or more acoustic harmonic amplitudes for each of the one or more acoustic harmonic frequencies based on the particular frequency band of the SPL frequency graph, and using the transfer function data elements to generate the band-specific compensation electrical signal. The compensation electrical signal may correspond to an acoustic harmonic signal including one or more acoustic harmonic frequencies for each of the one or more acoustic harmonic amplitudes.

[0010] An embodiment of the present invention may include a system for controlling the loudness of an electro-acoustic transducer.

[0011] An embodiment of the system may include a compensation module, a superposition module, a non-transitory memory device in which a module of instruction code may be stored, and at least one processor associated with the memory device, wherein the at least one processor may be configured to execute the module of instruction code.

[0012] Upon execution of these modules of instruction code, the processor may be configured to receive a transfer function data element representing a transfer function between (a) an electrical input to the electro-acoustic transducer and (b) an output sound pressure level (SPL) of the electro-acoustic transducer, apply the transfer function to the input electrical signal to obtain an expected SPL frequency graph of the electro-acoustic transducer, and identify at least one acoustic fundamental in the SPL frequency graph. The compensation module may be configured to generate a compensation electrical signal corresponding to an acoustic harmonic signal of the identified at least one acoustic fundamental. The superposition module may be configured to generate a superposition signal based on the input electrical signal and the compensation electrical signal, and provide the superposition signal as an input to the electro-acoustic transducer to control the loudness of the electro-acoustic transducer.

[0013] As described in more detail herein (eg, in relation to FIGS. 2 and 5), embodiments of the present invention may include a method for controlling loudness of an electro-acoustic transducer by at least one processor.

[0014] According to some embodiments, at least one processor (denoted herein as processor 110) may receive transfer function data elements representing a transfer function between (a) an electrical input and (b) an output sound pressure level (SPL) of an electro-acoustic transducer and apply the transfer function to the incoming electrical signal to obtain an expected SPL signal representing an expected SPL of the electro-acoustic transducer in response to the incoming electrical signal. The at least one processor may control a dedicated circuit (denoted herein as a compensation module) to identify at least one acoustic fundamental in the expected SPL signal and generate at least one compensation electrical signal corresponding to an acoustic overtone of the identified at least one acoustic fundamental. The at least one processor may then control the loudness (e.g., perceived volume) of the electro-acoustic transducer based at least in part on the at least one compensation electrical signal.

[0015] Additionally or alternatively, the at least one processor may control an electrical circuit (e.g., denoted herein as a superposition module) to generate a superposition electrical signal as a function (e.g., a weighted sum function) of the incoming electrical signal and the at least one compensation electrical signal. Embodiments of the invention may include providing the superposition signal as an input to an electro-acoustic transducer to control loudness of the electro-acoustic transducer.

[0016] According to some embodiments, the at least one processor may control a circuit (e.g., denoted herein as an analysis module) to segment the expected SPL signal into a plurality of band-specific SPL signals, each associated with a frequency passband or a frequency gap band. The at least one processor may then identify, for the at least one band-specific SPL signal associated with a frequency passband, at least one acoustic fundamental as a dominant sound (e.g., having the highest amplitude and / or the lowest frequency) represented by the band-specific SPL signal within the associated frequency passband.

[0017] Additionally or alternatively, for at least one band-specific SPL signal associated with a frequency passband, the at least one processor may determine one or more acoustic harmonic frequencies of the identified at least one acoustic fundamental based on the respective frequency passband, determine one or more acoustic amplitudes corresponding to the one or more acoustic harmonic frequencies based on the respective frequency passband, and generate a respective at least one harmonic SPL signal representative of the SPL of the one or more acoustic harmonic frequencies at the one or more corresponding acoustic amplitudes. In a complementary manner, the at least one processor may refrain from generating a respective harmonic SPL signal for at least one band-specific SPL signal associated with a frequency gap band.

[0018] According to some embodiments, the at least one processor may generate the compensation electrical signals by using the transfer function data elements to generate band-specific compensation electrical signals based on the at least one harmonic SPL signal. In other words, the at least one processor may generate the compensation electrical signals by obtaining an inverse transfer function data element representing an inverse version of a transfer function of the electro-acoustic transducer and applying the inverse transfer function to the at least one harmonic SPL signal to generate a respective compensation electrical signal. The compensation electrical signals may represent one or more acoustic harmonic frequencies and corresponding one or more acoustic amplitudes of the respective harmonic SPL signals.

[0019] According to some embodiments, each compensation electrical signal may correspond to or be dedicated to a unique set of acoustic harmonic frequencies. Additionally or alternatively, each compensation electrical signal may correspond to or be dedicated to a unique group of one or more harmonic SPL signals. At least one processor may control the superposition module to generate the superposition electrical signal as a weighted sum function of at least one compensation electrical signal and the incoming electrical signal.

[0020] According to some embodiments, the at least one processor may obtain or calculate a temporal acoustic power value representative of the acoustic power generated by the electro-acoustic transducer in response to input of the superimposed signal, and the at least one processor may then adjust one or more weights of the weighted sum function based on the obtained acoustic power value (e.g., to not exceed a predetermined acoustic power threshold).

[0021] Additionally or alternatively, the at least one processor may integrate or accumulate the temporal acoustic power values ​​over a predetermined time frame to obtain an acoustic energy value, also referred to herein as an acoustic dose value, and the at least one processor may then adjust one or more weights of the weighted sum function further based on the acoustic dose value (e.g., to avoid exceeding a predetermined acoustic dose threshold).

[0022] Additionally or alternatively, the at least one processor may receive one or more ID data elements representing identities of one or more users of the electro-acoustic transducer, for which the at least one ID data element may attribute a respective acoustic dose value and adjust one or more weights of the weighted sum function further based on the ID data element (e.g., to not exceed a predetermined personalized acoustic dose threshold).

[0023] As detailed herein (e.g., in connection with FIGS. 2, 5), embodiments of the present invention may include a system for controlling loudness of an electro-acoustic transducer by at least one processor. System embodiments may include analysis module circuitry, compensation module circuitry, and / or superposition module circuitry configured to implement a method for controlling loudness of an electro-acoustic transducer as detailed herein. Additionally or alternatively, system embodiments may further include a non-transitory memory device in which modules of instruction code are stored, and a processor associated with the memory device and configured to execute the modules of instruction code.

[0024] Upon executing the modules of instruction code, the processor may be configured to receive a transfer function data element representing a transfer function between (a) an electrical input and (b) an output sound pressure level (SPL) of the electro-acoustic transducer, apply the transfer function to the incoming electrical signal to obtain an expected SPL signal representing an expected SPL of the electro-acoustic transducer in response to the incoming electrical signal, identify at least one acoustic fundamental in the expected SPL signal, generate at least one compensation electrical signal corresponding to an acoustic overtone of the identified at least one acoustic fundamental, and control the loudness of the electro-acoustic transducer based at least in part on the at least one compensation electrical signal.

[0025] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and method of operation, together with its objects, features, and advantages, may best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which: Embodiments of the invention are illustrated by way of example, and not limitation, in the accompanying figures in which like reference characters indicate corresponding, similar or similar elements. [Brief description of the drawings]

[0026] [Figure 1] 1 is a high-level block diagram of an exemplary computing device in accordance with an embodiment of the present invention. [Diagram 2] 1 is a block diagram illustrating a system for controlling loudness of an electro-acoustic transducer according to an embodiment of the present invention. [Figure 3A] FIG. 2 is a schematic diagram illustrating a transfer function between (a) the electrical input to an electro-acoustic transducer and (b) the output SPL of the electro-acoustic transducer, according to an embodiment of the present invention. [Figure 3B] 1 is a graph showing a non-limiting example of the magnitude (in dB(A)) of a transfer function H(f) of a typical electro-acoustic transducer (e.g., a headphone) as a function of frequency. [Figure 3C]1 is a graph showing a non-limiting example of an SPL graph of a typical electro-acoustic transducer (e.g., headphones) as a function of frequency obtained by introducing a constant input electrical signal of 1 volt. [Figure 4A] 2 is a schematic block diagram illustrating an example implementation of one or more band-specific compensation function modules and a convolution module according to an embodiment of the present invention. [Figure 4B] 4 is a graph illustrating a band-specific compensation function provided by a band-specific compensation module according to an embodiment of the present invention. [Figure 4C] 1 is a schematic diagram illustrating aspects of the functionality of a system 100 for controlling loudness in an electro-acoustic transducer, according to an embodiment of the present invention. [Diagram 5] 4 is a flow diagram illustrating a method for controlling loudness of an electro-acoustic transducer according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] It will be understood that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn accurately or to scale. For example, dimensions of some elements may be exaggerated relative to other elements or several physical components may be included in a single functional block or element for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0028] In the following detailed description, many specific details are described to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In some cases, well-known methods, procedures, components, modules, units, and / or circuits have not been described in detail so as not to obscure the present invention. Some features or elements described with respect to one embodiment may be combined with features or elements described with respect to other embodiments. For clarity, the description of the same or similar features or elements may not be repeated.

[0029] For example, descriptions using terms such as "processing," "computing," "calculating," "determining," "establishing," "analyzing," "checking," and the like, may refer to operations and / or processes of a computer, computing platform, computing system, or other electronic computing device that manipulates and / or transforms data represented as physical (e.g., electronic) quantities in the registers and / or memory of the computer into other data similarly represented as physical quantities in the registers and / or memory of the computer or other non-transitory storage medium of information capable of storing instructions for performing an operation(s) and / or process(es). For example, although embodiments of the invention are not limited in this respect, the term "plurality" as used herein may include "multiple," or "two or more." The term "plurality" may be used throughout this specification to describe two or more components, devices, elements, units, parameters, and the like. The term set as used herein may include one or more items. Unless expressly stated, method embodiments described herein are not constrained to a particular order or sequence. In addition, some of the method embodiments described or elements thereof may occur or be performed simultaneously, at the same time, or in parallel.

[0030] The term sound pressure level (SPL) may be used herein to refer to the measurable physical value of the pressure level produced by a sound source. As is known in the art, an SPL level or value is usually expressed in units of decibels (e.g., dB(A)) and represents an increase or decrease in the sound produced.

[0031] The term "SPL graph" may be used herein to refer to a data element that represents the distribution of SPL (e.g., expressed in dB(A)) in the frequency domain. In other words, an SPL graph may represent the pressure level produced by a sound source as a function of the frequency content of the sound.

[0032] The term "electro-acoustic transducer" may be used herein to refer to a device or apparatus, such as headphones or earphones, configured to receive an input electrical signal and generate a corresponding audio signal.

[0033] The term "loudness" may be used herein to refer to the strength of an audio signal perceived by a listener or user of an electroacoustic transducer (e.g., a set of headphones) at the ear reference point (ERP). It will be understood that perceived loudness may correspond to a target SPL level at the ERP, but may nevertheless also be influenced by the hearing characteristics of a particular listener and personal psychoacoustic effects.

[0034] The term "volume" may be used herein to refer to a numerical data element or signal that may be input or introduced by a listener or user of an electroacoustic transducer (e.g., headphones). It will be understood that the input volume may depend on several factors including, for example, the recording level of the played music piece. Thus, the volume level may not directly correspond to a target SPL level. Instead, the volume level may be considered herein as a user's request to adjust (e.g., increase or decrease) a desired loudness level.

[0035] The human ear has no absolute measure of the loudness of an audio signal. Instead, the human ear can relate the loudness level of a sound source to the loudness of existing known sound sources. Loudness levels can also be classified by a listener based on the level of distortion contained in the audio signal. A distorted audio signal is generally perceived as louder than a signal of the same total sound pressure level without distortion. In other words, an audio signal that is distorted across the entire audible bandwidth (e.g., 15 Hz to 20 kHz) may be perceived as louder, despite being more distorted and less clear than an undistorted audio signal.

[0036] As described in more detail herein, embodiments of the present invention can exploit the effects of distortion on perceived loudness to enhance (eg, increase) the loudness of an audio signal without exceeding a given SPL limit.

[0037] Additionally or alternatively, embodiments of the present invention may split the audio signal into multiple different frequency bands (e.g., 2, 3, or 4 different frequency bands) and apply a different distortion function to each band. As described in more detail herein, such band-specific distortion functions may enable loudness enhancement while avoiding the audio signal being perceived as unclear or distorted.

[0038] Reference is now made to FIG. 1, which is a block diagram illustrating a computing device that may be included in one embodiment of a system for controlling the loudness of an electro-acoustic transducer, according to some embodiments.

[0039] Computing device 1 may include a processor or controller 2, which may be, for example, a central processing unit (CPU) processor, chip, or any suitable computing or computational device, an operating system 3, memory 4, executable code 5, a storage system 6, input devices 7, and output devices 8. Processor 2 (or one or more controllers or processors, possibly across multiple units or devices) may be configured to perform methods described herein and / or perform or function as various modules, units, etc. Systems according to embodiments of the present invention may include more than one computing device 1, and one or more computing devices 1 may function as components of systems according to embodiments of the present invention.

[0040] Operating system 3 may be or may include any code segment (e.g., similar to executable code 5 described herein) designed and / or configured to perform tasks including coordinating, scheduling, arbitrating, monitoring, controlling, or otherwise managing the operation of computing device 1, such as scheduling the execution of software programs or tasks, or enabling communication of software programs or other modules or units. Operating system 3 may be a commercially available operating system. It should be noted that operating system 3 may be an optional component, for example, in some embodiments, a system may include a computing device that does not require or includes an operating system 3.

[0041] The memory 4 may be or include, for example, a random access memory (RAM), a read only memory (ROM), a dynamic RAM (DRAM), a synchronous DRAM (SD-RAM), a double data rate (DDR) memory chip, a flash memory, a volatile memory, a non-volatile memory, a cache memory, a buffer, a short-term memory unit, a long-term memory unit, or other suitable memory or storage unit. The memory 4 may be or include multiple, possibly different, memory units. The memory 4 may be a non-transitory readable medium of a computer or a processor, or a non-transitory storage medium of a computer, for example, a RAM. In one embodiment, the non-transitory storage medium, such as the memory 4, a hard disk drive, or another storage device, may store instructions or code that, when executed by the processor, cause the processor to perform the methods described herein.

[0042] The executable code 5 may be any executable code, such as an application, a program, a process, a task, or a script. The executable code 5 may be executed by the processor or controller 2, possibly under the control of the operating system 3. For example, the executable code 5 may be an application that may control the loudness of an electro-acoustic transducer, as described further herein. Although a single item of executable code 5 is shown in FIG. 1 for clarity, systems according to some embodiments of the present invention may include multiple executable code segments similar to the executable code 5 that may be loaded into memory 4 and cause the processor 2 to perform the methods described herein.

[0043] The storage system 6 may be or may include, for example, a flash memory known in the art, a memory internal or embedded in a microcontroller or chip known in the art, a hard disk drive, a CD recordable (CD-R) drive, a Blu-ray disc (BD), a Universal Serial Bus (USB) device, or other suitable removable and / or fixed storage unit. Data relating to at least one electro-acoustic transducer may be stored in the storage system 6 and loaded from the storage system 6 into the memory 4 where it may be processed by the processor or controller 2. In some embodiments, some of the components shown in FIG. 1 may be omitted. For example, the memory 4 may be a non-volatile memory having the storage capacity of the storage system 6. Thus, although shown as a separate component, the storage system 6 may be embedded or included in the memory 4.

[0044] Input device(s) 7 may be or include any suitable input device, component, or system, such as a detachable keyboard or keypad, a mouse, etc. Output device(s) 8 may include one or more (possibly detachable) displays or monitors, speakers, and / or any other suitable output device. Any applicable input / output (I / O) devices may be connected to computing device 1 as indicated by blocks 7 and 8. For example, a wired or wireless network interface card (NIC), a universal serial bus (USB) device, or an external hard drive may be included in input device(s) 7 and / or output device(s) 8. It will be appreciated that any suitable number of input devices 7 and output devices 8 may be operatively connected to computing device 1 as indicated by blocks 7 and 8.

[0045] Systems according to some embodiments of the present invention may include components such as, but not limited to, multiple central processing units (CPUs) or any other suitable general-purpose or specific processors or controllers (e.g., similar to element 2), multiple input units, multiple output units, multiple memory units, and multiple storage units.

[0046] Reference is now made to FIG. 2, which is a block diagram illustrating a system 100 for controlling the loudness of at least one electro-acoustic transducer 50, according to an embodiment of the present invention.

[0047] According to some embodiments of the present invention, the system 100 may be implemented as software modules, hardware modules, or any combination thereof. For example, the system 100 may be or include a computing device, such as element 1 of FIG. 1, adapted to execute one or more modules of executable code (e.g., element 5 of FIG. 1) to control the loudness of the electro-acoustic transducer 140, as further described herein.

[0048] According to some embodiments, the system 100 may include at least one electro-acoustic transducer 50 to generate an audio signal 50A by the electro-acoustic transducer 50 based on an input electrical signal (e.g., 20, 130A) as described in detail herein.

[0049] Additionally or alternatively, the system 100 may be operatively or electrically connected to at least one electro-acoustic transducer 50, as shown in Figure 2. In such an embodiment, the system 100 may transmit at least one electrical signal 130A to the at least one electro-acoustic transducer 50. The at least one electro-acoustic transducer 50 may then generate an audio signal 50A based on the electrical signal 130A, as described further herein.

[0050] As shown in Figure 2, arrows may represent the flow of one or more data elements to and from system 100 and / or between modules or elements of system 100. Some arrows have been omitted from Figure 2 for clarity.

[0051] Reference is also made to Figure 3A, which is a schematic diagram illustrating a transfer function representing the conversion between (a) the electrical input to an electro-acoustic transducer 50 and (b) the output SPL of the electro-acoustic transducer 50, according to an embodiment of the present invention. Reference is also made to Figure 3B, which is a graph illustrating a non-limiting example of the magnitude (in dB(A)) of the transfer function H(f) of a typical electro-acoustic transducer (e.g., headphones) as a function of frequency.

[0052] The term “transfer function” may be used herein in connection with an electro-acoustic transducer to refer to the transformation between (a) the electrical input to the electro-acoustic transducer 50 and (b) the output sound pressure level of the electro-acoustic transducer 50.

[0053] For example, the electro-acoustic transducer 50 may be considered as a linear time-invariant (LTI) system that receives an input electrical signal V(t) and generates an output signal SPL(t) according to Equation 1A below: Formula 1A SPL(t)=V(t) * H(t) Where: V(t) is the time domain representation of the electrical input signal 20; SPL(t) is the time domain representation of the output sound pressure level 50A', H(t) is the time domain representation of the transfer function 50H of the electroacoustic transducer; " * " is the convolution operator.

[0054] Additionally or alternatively, the electro-acoustic transducer may generate an output signal SPL(f) according to the following Equation 1B: Formula 1B SPL(f)=V(f)·H(f) Where: V(f) is the frequency domain representation of the electrical input signal 20; SPL(f) is the frequency domain representation of the output sound pressure level 50A', H(f) is the frequency domain representation of the transfer function 50H of the electroacoustic transducer; "·" is the dot multiplication operator.

[0055] According to some embodiments, the system 100 may include an analysis module 120 configured to receive a transfer function data element 50H. The transfer function data element 50H may represent a transfer function between (a) an electrical input to the electro-acoustic transducer 50 and (b) an output sound pressure level (SPL) of the electro-acoustic transducer 50.

[0056] For example, transfer function data element 50H may be or include a vector of numerical elements that may represent values ​​of SPL signal 50A' over time that are expected to be output by electro-acoustic transducer 50 in response to impulse electrical input signal 20, according to Equation 1A above.

[0057] According to some embodiments, the analysis module 120 may also receive an input electrical signal 20 (e.g., shown as V(t) in Equation 1A). The input electrical signal 20 may correspond to or represent a respective audio signal, in the sense that the input electrical signal 20 may be utilized as an input by an electro-acoustic transducer (e.g., 50) to generate a corresponding audio signal (e.g., 50A).

[0058] It will be appreciated by those skilled in the art that the system 100 may be implemented as analog and / or digital circuitry associated with or integrated with an electro-acoustic transducer. In such implementations, the term "signal" may be used to denote a physical signal, such as an analog electrical signal and / or a digital electrical signal. Additionally or alternatively, the system 100 may be implemented, at least in part, as a software module configured to control the loudness of an associated electro-acoustic transducer 50. In such implementations, the term signal may be used to denote a numerical representation or data element representing a physical signal, such as a digital electrical signal and / or an analog electrical signal. Thus, the terms "signal," "data element," and "graph" may be used interchangeably herein depending on the context.

[0059] The analysis module 120 may apply the transfer function 50H to the input electrical signal 20 to generate an expected SPL signal 120A (also referred to herein as an “expected SPL data element 120A” and an “expected SPL frequency graph 120A”). The expected SPL signal 120A may represent the expected SPL of the electro-acoustic transducer 50 in response to the incoming electrical signal 20. In other words, the analysis module 120 may generate an SPL signal 120A that represents an expected audio signal in the frequency domain.

[0060] The term “expected” may be used in this context to refer to the theoretical audio signal that may be output by electro-acoustic transducer 50 when input electrical signal 20 is used as an input to electro-acoustic transducer 50.

[0061] The analysis module 120 may be implemented as a combination of hardware and software modules for applying the transfer function 50H to the input electrical signal 20 to generate the expected SPL signal 120A. For example, the signal 20 may be an analog electrical signal representing the initially required acoustic signal. The analysis module 120 may sample the incoming signal 20 over a predetermined time period and digitize the samples of the signal 20 using an analog-to-digital converter to generate a digital version of the incoming signal 20. The analysis module 120 may then, in cooperation with the processing unit 110 (which may be the same as the processor 2 of FIG. 1), apply the transfer function 50H (e.g., as detailed in connection with Equation 1A and / or Equation 1B) to the digitized samples of the incoming signal 20, thereby generating the expected SPL signal 120A.

[0062] See also Figure 3C, which is a frequency graph illustrating a non-limiting example of an expected SPL signal 120A of a typical electro-acoustic transducer (e.g., headphones) as a function of frequency resulting from introducing a 1 volt constant input electrical signal 20. It will be appreciated that such a constant input may generate an expected SPL signal graph 120A similar to the H(f) magnitude graph of Figure 3B, based on Equation 1B.

[0063] According to some embodiments, the analysis module 120 may include one or more frequency band filter modules 121 (or "filters 121" for short) which may be or include analog and / or digital band pass and / or band stop filters known in the art. The filters 121 may be configured to split or segment the expected SPL signal 120A into multiple frequency bands 121A. The frequency bands 121A may include one or more frequency pass bands 121AP that define frequency bands over which the system 100 may analyze the expected SPL signal 120A, and one or more frequency gap bands 121AG that define frequency bands over which the system 100 may refrain from analyzing the expected SPL signal 120A, as described in more detail herein. It will therefore be appreciated that one or more filter modules 121 may segment or divide the expected SPL signal 120A into multiple band-specific SPL signals 121B, each associated with a respective frequency passband 121AP (and thus denoted as passband SPL signal 121BP) or frequency gap band 121AG (and thus denoted as gap band SPL signal 121BG).

[0064] Additionally or alternatively, the analysis module 120 may apply one or more filter modules 121 to the input electrical signal 20 to generate multiple band-specific components of the input electrical signal 20, and then apply a transfer function 50H to the multiple band-specific components of the input electrical signal 20 to generate multiple band-specific SPL signals 121B (e.g., 121BG, 121BP).

[0065] The frequency passband 121AP may include, for example, (a) a first frequency band (e.g., 15 Hz to 50 Hz) in which the acoustic fundamental tone of deep bass is detected, (b) a second frequency band (e.g., 50 Hz to 100 Hz) in which the acoustic fundamental tone of low bass is detected, (c) a third frequency band (e.g., 100 Hz to 250 Hz) in which the acoustic fundamental tone of low vocal sounds is detected, and (d) a fourth frequency band (e.g., 250 Hz to 1 kHz) in which the acoustic fundamental tone of mid-high vocal sounds and instrumental sounds is detected.

[0066] The term "acoustic fundamental" may be used herein to denote the base or core frequency of a sound. As is known in the art, the acoustic fundamental comprises the lowest frequency component of an associated sound plus integer products of the acoustic fundamental. These integer products of the acoustic fundamental are commonly referred to in the art as "harmonics."

[0067] Acoustic fundamentals are shown herein as elements 122 having frequencies 122FR and corresponding amplitudes 122AMP. Harmonics are shown herein as elements 123 having harmonic frequency values ​​123FR and corresponding amplitudes 123AMP.

[0068] According to some embodiments, the analysis module 120 may identify the frequency 122FR of at least one acoustic fundamental tone 122 in the expected SPL signal 120A. In some embodiments, the analysis module 120 may identify the at least one acoustic fundamental tone frequency 122FR in a particular frequency passband 121AP and refrain from identifying the at least one acoustic fundamental tone frequency 122FR in the frequency gap band 121AG. In other words, for at least one band-specific SPL signal 121BP associated with a frequency passband 121AP, the analysis module 120 may identify at least one acoustic fundamental tone 122 as a dominant tone (e.g., having the lowest frequency 122FR and / or the highest amplitude 122AMP) represented by the band-specific SPL signal 121BP within the associated frequency passband 121AP.

[0069] With respect to the above example, the analysis module 120 may (a) identify at least one acoustic fundamental frequency 122FR and amplitude 122AMP of a deep bass sound in the first frequency pass band 121AP, (b) identify at least one acoustic fundamental frequency 122FR and amplitude 122AMP of a bass sound in the second frequency pass band 121AP, (c) identify at least one acoustic fundamental frequency 122FR and amplitude 122AMP of a low vocal sound in the third frequency pass band 121AP, and / or (d) identify at least one acoustic fundamental frequency 122FR and amplitude 122AMP of a mid-high vocal or instrumental sound in the fourth frequency pass band 121AP.

[0070] 2, the system 100 may include one or more band-specific compensation function modules 130. According to some embodiments, the band-specific compensation function modules 130 may be configured to receive the input electrical signal 20 and, in cooperation with the analysis module 120, generate at least one compensated electrical signal 136A. Additionally, as described in more detail herein, the one or more band-specific compensation function modules 130 may, in cooperation with the superposition module 140, perform band-specific compensation or adjustment of the input electrical signal 20 to generate an enhanced electrical signal 140A.

[0071] Reference is also made to FIG. 4A, which is a simplified block diagram illustrating the operation of one or more band-specific compensation function modules 130 (or simply "compensation modules 130") and a convolution module 140, according to an embodiment of the present invention.

[0072] According to some embodiments, the analysis module 120 may identify at least one acoustic fundamental 122 as being associated with a particular frequency passband 121AP of the expected SPL signal 120A and communicate the frequency 122FR and / or amplitude 122AMP of the identified acoustic fundamental 122 to an associated band-specific compensation function module 130. The term "associated" may be understood in the sense that the communicating compensation function module 130 is dedicated to or assigned to processing the SPL signal 121BP of the particular frequency passband 121AP.

[0073] As described in more detail herein, the compensation function module 130 may then perform band-specific (e.g., within the passband 121AP) compensation or adjustment of the incoming electrical signal 20 based on or in response to the frequency 123FR and / or amplitude 123AMP of the acoustic overtones 123 of the identified at least one acoustic fundamental 122.

[0074] According to some embodiments, the compensation module(s) 130 may generate at least one compensation electrical signal 136A corresponding to or representative of the acoustic overtones 123 of the identified at least one acoustic fundamental 122. The compensation module(s) 130 may then cooperate with the superposition module 140 to generate the superposition electrical signal 140, also referred to herein as enhanced electrical signal 140A, as a function of the incoming electrical signal 20 and the at least one compensation electrical signal 136A. For example, the superposition module 140 may apply a weighted sum function to the incoming electrical signal 20 and the at least one compensation electrical signal 136A to add or accumulate the band-specific compensation electrical signal 136A to the incoming electrical signal 20, thereby generating the superposition electrical signal 140A.

[0075] The superimposed electrical signal 140A may be referred to as an enhanced electrical signal 140A in the sense that it may act as an input to the electro-acoustic transducer 50 to generate a subsequent enhanced audio signal 50A. The term "enhanced" may be used in this context to indicate that the audio signal 50A is perceived by a listener or user of the electro-acoustic transducer 50 as having an increased loudness level at the ear reference point (ERP) and yet is not perceived by the user as distorted or unclear.

[0076] As described in detail herein, the superposition module 140 may modify the weight of the compensation electrical signal 136A in the enhanced electrical signal 140A according to predefined requirements and / or scenarios. In other words, the superposition module 140 may provide the superposition signal as an input to the electro-acoustic transducer 50 to control the loudness of the electro-acoustic transducer 50 based at least in part on the at least one band-specific compensation electrical signal 136A.

[0077] The compensation module 130 may be “band-specific” in the sense that the identified acoustic fundamental 122 frequencies 122FR of each frequency band 121A may be processed separately or in a different manner for each band to avoid the audio signal 50A being perceived as distorted, as described in more detail herein.

[0078] According to some embodiments, the compensation module 130 may include a harmonic compensation module 134 configured to receive (eg, from the analysis module 120) values ​​of the acoustic fundamental frequencies 122FR and respective acoustic fundamental amplitudes 122AMP.

[0079] Reference is also made to FIG. 4B, which is a schematic graph illustrating a band-specific compensation function provided by band-specific compensation module 130, according to an embodiment of the present invention.

[0080] 4B, an expected SPL signal 120A may be split into multiple passbands 121AP and / or gap bands 121AG (thus resulting in band-specific SPL signals 121B) by multiple filters 121. An acoustic fundamental 122 in passband 1 is represented as an approximate delta function with a frequency 122FR of 50 Hz.

[0081] The harmonic compensation module 134 may then determine or add one or more harmonics 123 having respective harmonic frequency values ​​123FR and corresponding harmonic amplitude values ​​123AMP based on the received acoustic fundamental values ​​122FR, 122AMP.

[0082] The one or more harmonic values ​​123FR, 123AMP may include, for example, one or more harmonic frequency values ​​123FR that correspond to harmonics of the acoustic fundamental frequency 122FR. In other words, the one or more harmonic frequency values ​​123FR may be integer product values ​​of the acoustic fundamental frequency 122FR.

[0083] According to some embodiments, for at least one band-specific SPL signal 121BP associated with a frequency passband 121AP, the harmonic compensation module 134 may determine frequencies 123FR of one or more acoustic harmonics 123 of the identified at least one acoustic fundamental 122 based on the respective frequency passband. For example, the harmonic compensation module 134 may be configured to determine a first number of harmonics for the first fundamental 122 in the first frequency passband 121AP and to determine a second, different number of harmonics for the second fundamental 122 in the second frequency passband 121AP.

[0084] Additionally or alternatively, the harmonic compensation module 134 may determine one or more acoustic amplitudes 123AMP corresponding to one or more acoustic harmonic frequencies 123FR based on the respective frequency passbands 121AP. For example, the harmonic compensation module 134 may be configured to determine a first amplitude 123AMP for a first harmonic in a first frequency passband 121AP and a second, different amplitude 123AMP for a second harmonic in a second frequency passband 121AP.

[0085] Additionally or alternatively, the harmonic compensation module 134 may be configured to determine a first amplitude 123AMP for a first harmonic resulting from the fundamental tone 122 in the first frequency passband 121AP and to determine a second, different amplitude 123AMP for a second harmonic resulting from the fundamental tone 122 in the second frequency passband 121AP.

[0086] For example, as shown in FIG. 4B, the harmonic compensation module 134 may produce harmonics 123 from the second to fourth order (represented by range A) in passbands (121AP) 1 and 2, and harmonics 123 from the fortieth to eightieth order (represented by range B) in passband (121AP) 3.

[0087] Thus, the harmonic compensation module 134 may generate at least one harmonic SPL signal 124 representing the SPL of one or more acoustic harmonics 123 at one or more corresponding acoustic amplitudes 123AMP at frequencies 123FR.

[0088] Additionally or alternatively, the harmonic compensation module 134 may refrain from generating harmonics 123 in the gap band 121AG or derived from the fundamental 122 in the gap band 121AG. In other words, for at least one band-specific SPL signal associated with a frequency gap band 121AG, the harmonic compensation module 134 may refrain from generating the respective harmonic SPL signal.

[0089] As described herein, one or more harmonic amplitude values ​​123AMP may represent the amplitude of one or more harmonic frequency values ​​123FR of each of the acoustic fundamentals 122. With the transfer function 50H and the SPL 120 at ERP known, the harmonic compensation module 134 may determine, based on a predefined rule or configuration, one or more harmonic values ​​(e.g., harmonic frequencies 123FR and respective harmonic amplitudes 123AMP) such that the loudness of the audio signal 50A is enhanced without adversely affecting the sound impression, e.g., without being perceived as distorted by a listener.

[0090] For example, the harmonic compensation module 134 may be configured to avoid adding harmonic content 123 at frequency 123FR relative to the fundamental frequency 122FR at which the expected SPL graph 120A exhibits a peak.

[0091] Additionally or alternatively, the harmonic compensation module 134 may be configured to add harmonic components 123 having harmonic frequencies 123FR at which the expected SPL graph 120A exhibits a trough.

[0092] Additionally or alternatively, the harmonic compensation module 134 may be configured to add a harmonic frequency 123FR component at a particular harmonic amplitude 123AMP (the harmonic amplitude 123AMP is selected based on the amplitude of the expected SPL graph 120 at the harmonic frequency 123FR).

[0093] Additionally or alternatively, the harmonic compensation module 134 may (a) add harmonic frequency 123FR components having high amplitude 123AMP at frequencies where the expected SPL graph 120 exhibits or includes low amplitudes (e.g., below a predefined threshold), and (b) add harmonic frequency 123FR components having low amplitude 123AMP at frequencies where the expected SPL graph 120 exhibits or includes high amplitudes (e.g., above a predefined threshold).

[0094] Additionally or alternatively, the harmonic compensation module 134 may determine one or more acoustic harmonic frequencies 123FR of the identified at least one acoustic fundamental 122 based on a particular frequency band 121A of the expected SPL frequency graph 120A.

[0095] Additionally or alternatively, the harmonic compensation module 134 may determine one or more acoustic harmonic amplitudes 123AMP for each of the one or more acoustic harmonic frequencies 123FR based on a particular frequency band 121A of the expected SPL frequency graph 120A.

[0096] It will be appreciated that such band-specific determination of the acoustic harmonic frequencies 123FR and their respective amplitudes makes it possible to avoid the sensation of distortion when listening to the enhanced audio signal 50A.

[0097] For example, (a) for a first frequency band 121A (e.g., 121AP from 15 Hz to 50 Hz), the harmonic compensation module 134 may determine a first number or set of acoustic harmonic frequencies 123FR having respective first amplitudes 123AMP, (b) for a second frequency band 121A (e.g., 121AP from 250 Hz to 1 KHz), the harmonic compensation module 134 may determine a second number or set of acoustic harmonic frequencies 123FR having respective second amplitudes 123AMP, and so on.

[0098] According to some embodiments, the compensation module 130 may include a compensation signal generator 136 adapted to receive the one or more harmonic frequencies 123FR and the respective one or more harmonic amplitudes 123AMP from the harmonic compensation module 134.

[0099] The compensation signal generator 136 may include circuitry configured to generate a band-specific compensation electrical signal 136A using the transfer function data elements 50H. The compensation electrical signal 136A may correspond to or be based on at least one acoustic harmonic SPL signal 124 including one or more acoustic harmonic frequencies 123FR at respective one or more acoustic harmonic amplitudes 123AMP.

[0100] In other words, the compensation signal generator 136 may use information of the transfer function H(f) of Equation 1B (represented by transfer function data element 50H) to generate a compensation electrical signal 136A corresponding to one or more acoustic harmonic frequency 123FR components having respective one or more acoustic amplitudes 123AMP.

[0101] The compensation electrical signal 136A may be said herein to "correspond" to the acoustic harmonic SPL signal 124 of at least one identified acoustic fundamental 122 in the sense that when the compensation electrical signal 136A is used as an input to the electro-acoustic transducer 50, the electro-acoustic transducer 50 generates an audio signal 50A including determined harmonic frequencies 123FR at respective determined harmonic amplitudes 123AMP (based on the transfer function H(f)50H).

[0102] The compensation electrical signal 136A may be referred to herein as “band-specific” in the sense that the compensation signal generator 136 may generate different compensation electrical signals 136A depending on the association of the identified acoustic fundamental 122 with a particular frequency band 121A.

[0103] According to some embodiments, the compensation signal generator 136 may be implemented as a combination of hardware and software modules for applying the inverse of the transfer function 50H to at least one harmonic SPL signal 124 to generate a respective band-specific compensation electrical signal 136A.

[0104] For example, the harmonic SPL signal 124 may be a digital signal or digital representation of the required acoustic harmonic 123. The compensation signal generator 136, in cooperation with the processor 110 (such as processor 2 in FIG. 1), may generate (e.g., received via input 7 in FIG. 1 or calculated) an inverse transfer function data element 50' representing an inverse version of the electro-acoustic transducer transfer function 50. The compensation signal generator 136 may then apply the inverse transfer function to the at least one harmonic SPL signal 124 (e.g., in a manner similar to Equation 1B) to generate a respective band-specific digital representation of the required compensation electrical signal 136A. The compensation signal generator 136 may then apply a digital-to-analog converter to generate the analog band-specific compensation electrical signal 136A. The compensation signal 136A may represent (i) one or more acoustic harmonic frequencies and (ii) one or more corresponding acoustic amplitudes of each band-specific harmonic SPL signal 124.

[0105] Reference is also made to FIG. 4C, which is a schematic diagram illustrating aspects of the functionality of a system 100 for controlling loudness in an electro-acoustic transducer, according to an embodiment of the present invention.

[0106] 4C, module 120 may apply filters 121 to split the processing of incoming signal 20 into multiple band-specific channels. Each band-specific compensation function module 130 may generate a band-specific compensation electrical signal 136A, thus resulting in multiple band-specific compensation electrical signals 136A. Superposition module 140 may add, sum, or accumulate (e.g., by a weighted sum function) the multiple band-specific compensation electrical signals 136A with the incoming signal 20 to generate a single, combined, enhanced electrical signal 140A.

[0107] Additionally or alternatively, each compensation electrical signal 136A may correspond to a unique set of frequencies 123FR of acoustic harmonics 123, and the superimposed electrical signal 140A may be generated as a weighted sum function of the compensation electrical signal 136A and the incoming electrical signal 20. Additionally or alternatively, each compensation electrical signal 136A may correspond to a unique group of one or more harmonic SPL signals 124, and the superimposed electrical signal 140A may be generated as a weighted sum function of at least one compensation electrical signal 136A and the incoming electrical signal 20.

[0108] For example, the compensation signal generator 136 of the first band-specific compensation function module 130 may generate a first band-specific compensation electrical signal 136A for a first acoustic fundamental 122 identified as belonging to or included in a first frequency passband 121AP, the compensation signal generator 136 of the second band-specific compensation function module 130 may generate a second band-specific compensation electrical signal 136A for a second acoustic fundamental 122 identified as belonging to or included in a second frequency passband 121AP, and so on.

[0109] According to some embodiments, the superposition module 140 may be configured to perform a superposition or weighted sum of multiple band-specific compensation electrical signals 136A and the incoming electrical signal 20 to generate the superposition signal 140A in order to comply with legal regulations and limitations. Since the frequency and amplitude of the added harmonic frequency components 123FR and the transfer function H(f) are known, the superposition module 140 can ensure that the legal limit of the maximum SPL is never exceeded.

[0110] According to some embodiments, the system 100 may obtain a temporal acoustic power value 140C representative of the acoustic power generated by the electro-acoustic transducer 50 in response to the input of the superimposed signal 140A, and may adjust one or more weights of the harmonic components 123 and / or the incoming signal 20 in the weighted sum function based on the obtained acoustic power value 140C.

[0111] For example, the processor 110 may apply a transfer function 50H (e.g., H(f) in Equation 1B) to calculate an expected SPL graph 140B of the superimposed signal 140A. The superimposition module 140 may then calculate a power 140C of the superimposed signal 140A, e.g., as the signal squared integral of the SPL graph 140B over the audible bandwidth. If the power 140C of the superimposed signal 140A exceeds a predefined limit due to the power contribution of the harmonic components 123 in all SPL 120A bands 121A, the superimposition module 140 may, for example, reduce the weight of the incoming signal 20 in generating the superimposed signal 140A. For example, if (a) the value of power 140C of superimposed signal 140A reaches a predefined limit and (b) the contribution of harmonic frequency components 123 in all SPL 120A bands amounts to a total percentage of 10% of the original signal 20, the superimposition module 140 may reduce the portion of the original incoming signal 20 by 0.83 dB (decibels) in generating the superimposed signal 140A.

[0112] According to some embodiments, system 100 may transmit or provide superimposed signal 140A as an input to electro-acoustic transducer 50. As described in more detail herein, adding or superimposing compensation electrical signal 136A to original input electrical signal 20 may (a) comply with safety regulations, (b) take into account an individual's cumulative acoustic load, (c) provide a loudness that is pleasing to an individual listener, and (d) control the loudness of the electro-acoustic transducer in a manner that avoids a noticeable sensation of sound distortion.

[0113] According to some embodiments, the compensation module 130 may be used in multiple operating modes to provide a required sound enhancement effect, each such operating mode may be associated with a particular condition or scenario, as detailed herein.

[0114] For example, the first operating mode may be referred to herein as an "enhanced constant" operating mode. In the enhanced constant operating mode, the compensation module 130 may add harmonic components (e.g., components having harmonic frequencies 123FR and respective harmonic amplitudes 123AMP) regardless of the required volume setting 40. In other words, in the enhanced constant operating mode, the compensation module 130 may add a predefined amount of harmonic components (e.g., 10% of the total power 140C) in all SPL frequency bands 121A.

[0115] Another mode of operation may be referred to herein as a "volume boost increase" mode of operation. In the volume boost increase mode of operation, the compensation module 130 may add harmonics 123 and / or increase a portion (e.g., amplitude) of the harmonics 123 in the total power 140C as the required total volume 40 increases. For example, the amount of power contributed by the additional harmonics 123 (e.g., the number of harmonics 123 and / or their amplitudes 123AMP) in one or more (e.g., all) frequency bands 121BP may increase in proportion to the increase in volume demand 40, starting at 0% of power 140C to a maximum value (e.g., 10%) at the maximum volume setting.

[0116] Another operating mode may be referred to herein as a "volume boost maximum" operating mode. In the volume boost maximum operating mode, the compensation module 130 may add harmonic components 123 and / or increase a portion of the harmonic components (e.g., amplitude 123AMP) in the total power 140C when the required volume 40 reaches a predefined threshold or limit (e.g., maximum, 10%, 20%, 30% below maximum, etc., or any other predefined limit). For example, when the required maximum volume setting 40 of the headphones is reached, the compensation module 130 may increase only a portion of the additional harmonic components 123 in the power 140C, e.g., from 0% to 10%.

[0117] Another mode of operation may be referred to herein as a "dosimeter-enhanced" mode. According to some embodiments, the system 100 may include a personalized dosimeter module 160 configured to receive the temporal acoustic power 140C and sum or integrate the total amount of power 140C over a predefined time frame (e.g., a moving time frame) to generate an acoustic dose value 160A. In other words, the personalized dosimeter 160 may generate a dose data element 160A that represents the integral of the power 140C over a past predefined time frame. The convolution module 140 may then adjust one or more weights of the harmonic components 123 and / or the incoming signal 20 in the weighted sum function based on the acoustic dose value (e.g., to avoid exceeding a predefined dose limit).

[0118] According to some embodiments, the dosimeter 160 may be personalized for use by a particular listener or user. For example, the predefined time frame may be an hour, a day, and / or a week, and the dose data element 160A may represent the integral of the acoustic power (e.g., acoustic energy) absorbed by a particular listener over the past hour, day, and / or week. The dosimeter module 160 may be referred to herein as "personalized" in the sense that it may associate a particular dose 160A with a particular user or listener, thus facilitating personalized enhancement and / or limitation of the acoustic signal 50A.

[0119] For example, the dosimeter module 160 may include or be communicatively connected to the identifier module 150. The identifier module 150 may be configured to receive (e.g., via the input device 7 of FIG. 1 ) one or more ID data elements 150A (e.g., name, serial number, etc.) representing the identity of one or more users of the electro-acoustic transducer 50 (e.g., a headphone set), for example, whenever the electro-acoustic transducer 50 (e.g., a headphone set) is used. In this context, the term "used" may refer to the state in which the electro-acoustic transducer or headphone is placed on a person's ear and / or the audio signal 50A is generated. Thus, the dosimeter module 160 may accumulate the power 140C over a moving time frame to generate a personalized dose 160A and associate the personalized dose 160A with the identified user.

[0120] In the dosimeter-enhanced operating mode, the compensation module 130 and / or the superposition module 140 may adjust one or more weights of the weighted sum function further based on the ID data element 150A. For example, the compensation module 130 may add harmonic components and / or increase a portion (e.g., amplitude) of harmonic components in the total power 140C according to the personalized dose 160A.

[0121] For example, the personalized dose 160A may indicate that a particular listener has reached a maximum daily or weekly dose. Alternatively, the personalized dose 160A may indicate that a particular listener has reached a particular percentage of the daily or weekly dose (e.g., 75% of the daily or weekly dose, 90% of the daily or weekly dose, etc.). In such an embodiment, the compensation module 130 and / or the superposition module 140 may (a) increase the proportion of harmonic content in the superposition signal 140A and (b) reduce the overall amplitude of the superposition signal 140. Such settings may reduce the power 140C and still provide a satisfying loudness sensation to a particular user or listener.

[0122] FIG. 5 is a flow diagram illustrating a method of controlling the loudness of an electro-acoustic transducer (e.g., element 50 in FIG. 2) by at least one processor, such as processor 2 in FIG. 1 (which may be the same as processor 110 in FIG. 2), in accordance with some embodiments of the present invention.

[0123] As described in more detail herein, the processor 2 may control or cooperate with one or more software and / or hardware modules (e.g., the analysis module 120, the compensation module 130, the superposition module 140, the dosimeter 160, and / or the discriminator 150 of the system 100 of FIG. 2) to generate the superposed signal 140A of FIG. 2. The superposed signal 140 may then be used as an input to the electro-acoustic transducer 50 to generate the enhanced audio signal 50A.

[0124] As shown in step S1005, at least one processor 2 (e.g., 110) may receive a transfer function data element (e.g., element 50H in FIG. 2) representing a transfer function (e.g., H(f) in FIGS. 3A, 3B) between (a) the electrical input to the electro-acoustic transducer 50 (e.g., element 20 in FIG. 2) and (b) the output sound pressure level of the electro-acoustic transducer 50 (e.g., SPL50A' in FIG. 3A).

[0125] As shown in step S1010, at least one processor 2, in cooperation with analysis module 120, may apply a transfer function H(f) to the input electrical signal. Thus, processor 2 may generate expected SPL frequency graph 120A of FIG. 2 and / or FIG. 3C for electro-acoustic transducer 50.

[0126] As shown in step S1015, the at least one processor 2 may identify at least one acoustic fundamental 122 of FIG. 2 in the expected SPL frequency graph 120A.

[0127] As shown in step S1020, the at least one processor 2 may cooperate with one or more band-specific compensation function modules 130 to generate one or more band-specific compensation electrical signals 136A. The one or more band-specific compensation electrical signals 136A may each correspond to an acoustic harmonic signal of the identified at least one acoustic fundamental 122.

[0128] For example, (a) for a first acoustic fundamental 120B identified as belonging to or included in a first frequency band 121AP, the first band-specific compensation function module 130 may generate a first band-specific compensation electrical signal 136A, (b) for a second acoustic fundamental 122 identified as belonging to or included in a second frequency band 121AP, the second band-specific compensation function module 130 may generate a second band-specific compensation electrical signal 136A, and so on.

[0129] As shown in step S1025, at least one processor 2, in cooperation with a superposition module 140, may generate the superposition 140 of FIG. 2 based on the input electrical signal 20 and the compensation electrical signal(s) 136A.

[0130] As shown in step S1030, at least one processor 2 can provide the superimposed signal 140 as an input to the electro-acoustic transducer 50 and thus control the loudness of the electro-acoustic transducer in a manner that (a) complies with safety regulations, (b) takes into account personal acoustic dosage accumulation, (c) provides a loudness that is satisfactory for each individual listener, and (d) avoids the sensation of noticeable sound distortion.

Claims

1. 1. A method for controlling loudness of an electro-acoustic transducer by at least one processor, said method comprising: receiving a transfer function data element representing a transfer function between (a) an electrical input and (b) an output sound pressure level (SPL) of an electro-acoustic transducer; applying a transfer function to the incoming electrical signal to obtain an expected SPL signal representing an expected SPL of an electro-acoustic transducer in response to the incoming electrical signal; identifying at least one acoustic fundamental in the expected SPL signal; generating at least one compensation electrical signal corresponding to an acoustic overtone of the identified at least one acoustic fundamental; and controlling the loudness of an electro-acoustic transducer based at least in part on the at least one compensation electrical signal; A method comprising:

2. generating a superimposed electrical signal as a function of the incoming electrical signal and the at least one compensating electrical signal; and providing the superimposed signal as an input to an electro-acoustic transducer to control loudness of the electro-acoustic transducer; The method of claim 1 further comprising:

3. The method of any one of claims 1 to 2, further comprising segmenting the expected SPL signal into a plurality of band-specific SPL signals, each associated with a frequency passband or frequency gap band.

4. 4. The method of claim 3, wherein identifying the at least one acoustic fundamental comprises, for at least one band-specific SPL signal associated with a frequency passband, identifying the at least one acoustic fundamental as a dominant sound represented by the band-specific SPL signal within an associated frequency passband.

5. For at least one band-specific SPL signal associated with a frequency passband, determining one or more acoustic harmonic frequencies of the identified at least one acoustic fundamental based on the respective frequency passbands; determining one or more acoustic amplitudes corresponding to the one or more acoustic harmonic frequencies based on the respective frequency passbands; and generating at least one respective harmonic SPL signal representing the SPL of the one or more acoustic harmonic frequencies at the one or more corresponding acoustic amplitudes; The method of claim 4 further comprising:

6. The method of claim 4 , further comprising refraining from generating a respective harmonic SPL signal for at least one band-specific SPL signal associated with a frequency gap band.

7. The method of claim 4 , wherein generating the compensation electrical signal comprises using transfer function data elements to generate band-specific compensation electrical signals based on at least one harmonic SPL signal.

8. generating the compensation electrical signal obtaining an inverse transfer function data element representing an inverse version of the transfer function of the electro-acoustic transducer; and applying the inverse transfer function to the at least one harmonic SPL signal to generate a respective compensated electrical signal representing (i) one or more acoustic harmonic frequencies and (ii) a corresponding one or more acoustic amplitudes of the respective harmonic SPL signal; The method of claim 4 comprising:

9. 6. The method of claim 5, wherein each compensation electrical signal corresponds to a unique set of acoustic harmonic frequencies, and the superimposed electrical signal is generated as a weighted sum function of at least one compensation electrical signal and the incoming electrical signal.

10. 6. The method of claim 5, wherein each compensation electrical signal corresponds to a unique group of one or more harmonic SPL signals, and the superimposed electrical signal is generated as a weighted sum function of at least one compensation electrical signal and the incoming electrical signal.

11. obtaining a temporal acoustic power value representative of the acoustic power generated by the electro-acoustic transducer in response to input of the superimposed signal; and adjusting one or more weights of the weighted sum function based on the obtained acoustic power values; The method of claim 10 further comprising:

12. integrating the temporal acoustic power values ​​over a predetermined time period to obtain an acoustic dose value; and adjusting one or more weights of a weighted sum function further based on the acoustic dose value; The method of claim 10 further comprising:

13. receiving one or more identification data elements representing the identification of one or more users of the electro-acoustic transducer; attributing a respective acoustic dose value for said at least one ID data element; and adjusting one or more weights of a weighted sum function further based on said ID data element; The method of claim 12 further comprising:

14. 1. A system for controlling loudness of an electro-acoustic transducer, the system comprising: a compensation module; a superposition module; a non-transitory memory device in which a module of instruction code is stored; and a processor associated with the memory device and configured to execute the module of instruction code, wherein upon execution of the module of instruction code, the processor: receiving a transfer function data element representing a transfer function between (a) an electrical input and (b) an output sound pressure level (SPL) of an electro-acoustic transducer; applying a transfer function to the incoming electrical signal to obtain an expected SPL signal representing an expected SPL of the electro-acoustic transducer in response to the incoming electrical signal; identifying at least one acoustic fundamental in the expected SPL signal; generating at least one compensation electrical signal corresponding to an acoustic overtone of the identified at least one acoustic fundamental; controlling the loudness of an electro-acoustic transducer based at least in part on the at least one compensation electrical signal. The system is configured as follows:

15. The at least one processor further comprises: generating a superimposed electrical signal as a function of the incoming electrical signal and the at least one compensating electrical signal; providing the superimposed signal as an input to an electro-acoustic transducer to control the loudness of the electro-acoustic transducer; The system of claim 14 configured to:

16. The system of any one of claims 14 to 15, wherein the at least one processor is further configured to segment the expected SPL signal into a plurality of band-specific SPL signals, each associated with a frequency passband or a frequency gap band.

17. 16. The system of claim 14, wherein the at least one processor is further configured to identify, for at least one band-specific SPL signal associated with a frequency passband, at least one acoustic fundamental by identifying the at least one acoustic fundamental as a dominant sound represented by the band-specific SPL signal within the associated frequency passband.

18. The at least one processor may further calculate, for at least one band-specific SPL signal associated with a frequency passband: determining one or more acoustic harmonic frequencies of the identified at least one acoustic fundamental based on the respective frequency passbands; determining one or more acoustic amplitudes corresponding to the one or more acoustic harmonic frequencies based on the respective frequency passbands; generating at least one respective harmonic SPL signal representing the SPL of one or more acoustic harmonic frequencies at the one or more corresponding acoustic amplitudes; The system of claim 16 configured to:

19. 17. The system of claim 16, wherein the at least one processor is further configured to refrain from generating a respective harmonic SPL signal for at least one band-specific SPL signal associated with a frequency gap band.

20. 16. The system of claim 14, wherein the at least one processor is configured to generate the compensation electrical signal by using transfer function data elements to generate band-specific compensation electrical signals based on at least one harmonic SPL signal.

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