Apparatus and controlling method thereof

Abstract

An electronic device is disclosed. The electronic device includes an audio output unit and a processor that controls the audio output unit to scale the input audio signal based on a volume level when an audio signal is input, and if the volume level is greater than or equal to a first threshold level, apply a first gain to the scaled audio signal to adjust the intensity of the scaled audio signal, and if the intensity of the adjusted audio signal is greater than or equal to a threshold intensity, apply a second gain to the adjusted audio signal to readjust the intensity of the adjusted audio signal, and amplify and output the readjusted audio signal.

Description

Technology Field

[0001] The present disclosure relates to an electronic device and a method for controlling the same for increasing the perceived volume of a user in an audio device in which the output performance of the audio system is limited. Background Technology

[0002] Conventional electronic devices had a problem in that when simply amplifying the signal strength within a limited output strength to increase the output volume, distortion occurred in the parts exceeding the limited output strength. In particular, for so-called Peak-2-Peak (Full Scale) signals, where most of the components of the input audio signal correspond to the electronic device's limited output strength, this problem was bound to become more severe.

[0003] To address these issues, a method to secure an amplitude margin by compressing inputs exceeding a critical intensity can be applied; however, in this case, there was a problem where the linearity of the volume table deteriorated at high volume levels due to sound pressure loss caused by compression. The problem to be solved

[0004] The present disclosure is in accordance with the aforementioned necessity, and the purpose of the present disclosure is to provide an electronic device and a method for controlling the same that improves the reduction of the volume amplification effect at high volume levels. means of solving the problem

[0005] An electronic device according to one embodiment of the present disclosure includes an audio output unit and a processor that controls the audio output unit to scale the input audio signal based on a volume level when an audio signal is input, and if the volume level is greater than or equal to a first threshold level, apply a first gain to the scaled audio signal to adjust the intensity of the scaled audio signal, and if the intensity of the adjusted audio signal is greater than or equal to a threshold intensity, apply a second gain to the adjusted audio signal to readjust the intensity of the adjusted audio signal, and amplify and output the readjusted audio signal.

[0006] Here, in the interval where the volume level is above the first threshold level and below the maximum volume level, the strength of the audio signal can be adjusted in the form of a cubic function.

[0007] Here, when the volume level is at its maximum, the processor can adjust the strength of the audio signal based on the following mathematical formula.

[0008] y = (1+β)*x - β*x^3

[0009] Here, x is the strength of the input audio signal, y is the strength of the output audio signal, and β is a positive number less than or equal to 0.5.

[0010] Additionally, the first gain may be determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after the adjustment.

[0011] Here, the processor applies a third gain to the scaled audio signal if the volume level is greater than or equal to a second threshold level, and adjusts the strength of the applied audio signal by applying the first gain to the audio signal to which the third gain is applied if the volume level is greater than or equal to a first threshold level, and the second threshold level may be lower than the first threshold level.

[0012] Here, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain may be in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain may be in the form of a linearly decreasing function.

[0013] Here, the second threshold level can be determined by the characteristics of the TMC (Tone Mapping Curve).

[0014] Additionally, the processor maintains the strength of the adjusted audio signal if the strength of the adjusted audio signal is below the threshold strength, and if the strength of the adjusted audio signal is above the threshold strength, applies the second gain to the adjusted audio signal to readjust the strength of the adjusted audio signal, and at the threshold strength or higher, the strength of the audio signal after readjustment may be reduced compared to the strength of the audio signal before readjustment.

[0015] Meanwhile, the processor may preprocess the scaled audio signal by applying a fourth gain to the scaled audio signal if the strength of the scaled audio signal is greater than or equal to the threshold strength, and adjust the strength of the preprocessed audio signal by applying the first gain to the preprocessed audio signal.

[0016] A control method for an electronic device according to one embodiment of the present disclosure may include: a step of scaling the audio signal based on a volume level input by a user when the audio signal is input; a step of adjusting the intensity of the scaled audio signal by applying a first gain to the scaled audio signal when the volume level is above a first threshold level; a step of readjusting the intensity of the adjusted audio signal by applying a second gain to the adjusted audio signal when the intensity of the adjusted audio signal is above a threshold intensity; and a step of amplifying and outputting the readjusted audio signal.

[0017] Here, in the interval where the volume level is above the first threshold level and below the maximum volume level, the strength of the audio signal can be adjusted in the form of a cubic function.

[0018] Here, the step of adjusting the strength of the audio signal by applying the first gain can adjust the strength of the audio signal based on the following mathematical formula when the volume level is at its maximum.

[0019] y = (1+β)*x - β*x^3

[0020] Here, x is the strength of the input audio signal, y is the strength of the output audio signal, and β is a positive number less than or equal to 0.5.

[0021] Here, the first gain can be determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after the adjustment.

[0022] Additionally, the method further includes the step of applying a third gain to the scaled audio signal when the volume level is greater than or equal to a second threshold level, and the step of adjusting the strength of the applied audio signal by applying the first gain to the audio signal to which the third gain has been applied when the volume level is greater than or equal to a first threshold level, wherein the second threshold level may be lower than the first threshold level.

[0023] Here, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain may be in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain may be in the form of a linearly decreasing function.

[0024] Here, the second threshold level can be determined by the characteristics of the TMC (Tone Mapping Curve).

[0025] Additionally, the step of readjusting the strength of the adjusted audio signal comprises maintaining the strength of the adjusted audio signal if the strength of the adjusted audio signal is below the threshold strength, and readjusting the strength of the adjusted audio signal by applying the second gain to the adjusted audio signal if the strength of the adjusted audio signal is above the threshold strength, and the strength of the audio signal after readjustment at the threshold strength or higher may be reduced compared to the strength of the audio signal before readjustment.

[0026] Meanwhile, if the strength of the scaled audio signal is greater than or equal to the threshold strength, the method further includes a step of preprocessing the scaled audio signal by applying a fourth gain to the scaled audio signal, and the preprocessed audio signal can be adjusted by applying the first gain.

[0027] A computer-readable medium according to one embodiment of the present disclosure is a non-transient computer-readable medium that stores computer instructions that cause the electronic device to perform an operation when executed by a processor of the electronic device, wherein the operation may include: a step of scaling the audio signal based on a volume level when the audio signal is input; a step of adjusting the intensity of the scaled audio signal by applying a first gain to the scaled audio signal when the volume level is above a first threshold level; a step of readjusting the intensity of the adjusted audio signal by applying a second gain to the adjusted audio signal when the intensity of the adjusted audio signal is above a threshold intensity; and a step of amplifying and outputting the readjusted audio signal. Effects of the invention

[0028] According to various embodiments of the present disclosure, the volume of an input audio signal can be efficiently increased regardless of the type of input audio signal. Brief explanation of the drawing

[0029] FIGS. 1a and FIGS. 1b are drawings intended to explain the problems of the prior art. FIG. 2 is a block diagram for explaining the configuration of an electronic device according to one embodiment of the present disclosure. FIG. 3 is a block diagram illustrating the functional configuration of an electronic device according to one embodiment of the present disclosure. FIGS. 4a to 4c are drawings for explaining the compression and amplification operations of a scaled audio signal according to one embodiment of the present disclosure. FIGS. 5a to 5c are drawings for illustrating the signal strength of an amplified audio signal according to one embodiment of the present disclosure. FIG. 6 is a block diagram illustrating the basic configuration of an amplifier according to one embodiment of the present disclosure. Figure 7 is a diagram illustrating an example of an electronic device performing equalization through a TMC module. FIGS. 8a and FIGS. 8b are drawings for explaining gain adjustment operation according to one embodiment of the present disclosure. FIG. 9 is a diagram illustrating the change in output characteristics according to the change in delta value of the present disclosure. FIG. 10 is a drawing for explaining a sound pressure amplification mechanism of an electronic device according to one embodiment of the present disclosure. FIG. 11a is a diagram illustrating the volume table characteristics for a Peak-2-Peak input signal of an electronic device according to one embodiment of the present disclosure. FIG. 11b is a diagram illustrating volume table characteristics for a -24dB LKFS input signal of an electronic device according to one embodiment of the present disclosure. FIGS. 12a and FIGS. 12b are drawings illustrating an electronic device according to another embodiment of the present disclosure adjusting a delta value and a gain. FIG. 13a is a diagram illustrating volume table characteristics for a Peak-2-Peak input signal according to another embodiment of the present disclosure. FIG. 13b is a diagram illustrating volume table characteristics for a -24dB LKFS input signal according to another embodiment of the present disclosure. FIG. 14 is a block diagram for specifically explaining the functional configuration of an electronic device according to one embodiment of the present disclosure. FIG. 15 is a flowchart for explaining a method of controlling an electronic device according to one embodiment of the present disclosure. FIG. 16 is a flowchart for explaining a method of controlling an electronic device according to another embodiment of the present disclosure. Specific details for implementing the invention

[0030] Before specifically describing the present disclosure, the method of description in the specification and drawings is described.

[0031] First, the terms used in this specification and claims have been selected based on general terms considering their functions in the various embodiments of this disclosure. However, these terms may vary depending on the intent of those skilled in the art, legal or technical interpretations, and the emergence of new technologies. Additionally, some terms have been arbitrarily selected by the applicant. Such terms may be interpreted according to the meanings defined in this specification; in the absence of specific definitions, they may be interpreted based on the overall content of this specification and common technical knowledge in the relevant field.

[0032] In addition, the same reference numbers or symbols described in each drawing attached to this specification represent parts or components that perform substantially the same function. For convenience of explanation and understanding, the same reference numbers or symbols are used to describe different embodiments. That is, even if components having the same reference number are all depicted in multiple drawings, the multiple drawings do not imply a single embodiment.

[0033] Additionally, in this specification and claims, terms including ordinal numbers, such as "first," "second," etc., may be used to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from one another, and the meaning of the terms should not be limited by the use of such ordinal numbers. For example, the order of use or arrangement of components combined with such ordinal numbers should not be restricted by the number. If necessary, each ordinal number may be used interchangeably.

[0034] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "consisting of" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0035] In the embodiments of the present disclosure, terms such as "module," "unit," "part," etc. are used to refer to a component that performs at least one function or operation, and such component may be implemented in hardware or software, or in a combination of hardware and software. Additionally, a plurality of "modules," "units," "parts," etc. may be integrated into at least one module or chip and implemented as at least one processor, except where each needs to be implemented in specific individual hardware.

[0036] Furthermore, in the embodiments of the present disclosure, when a part is described as being connected to another part, this includes not only a direct connection but also an indirect connection through another medium. Additionally, the meaning that a part includes a certain component implies that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] Embodiments of the present disclosure are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present disclosure in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0038] FIGS. 1a and FIGS. 1b are drawings to aid in understanding one embodiment of the present disclosure.

[0039] Generally, the strength of the output audio signal is determined by scaling the input audio signal according to the volume level set by the user (hereinafter referred to as the output volume level). For example, the gain applied to the scaling may be based on a pre-set volume table as shown in FIG. 1a for each volume level.

[0040] According to FIG. 1a, the electronic device (100) applies a scaling gain of 1 when the output volume level is 100, and when the output volume level is lower than 100, scales the input signal by a gain of less than 1 (dB scale) corresponding to the volume table and outputs it.

[0041] Additionally, the electronic device (100) can amplify and output an input audio signal, and as illustrated in FIG. 1b, the electronic device (100) according to one embodiment of the present disclosure aims to increase the volume by 6 dB, that is, acoustically about twice, compared to before amplification when the output volume level is 100. However, the maximum output intensity of the system may be 0 dB.

[0042] Accordingly, the strength of the output signal amplified by the electronic device (100) cannot exceed 0dB. Nevertheless, the reason the target performance curve (11) is located in the region above 0dB is due to the relative increase in loudness with increasing sound pressure, which will be explained in detail in FIGS. 5a to 5c.

[0043] Specifically, audio inputs conforming to ITU standards have a total loudness of -24dB LKFS (Loudness K-Weighted Full Scale) or -23dB LUFS (Loudness Unit Full Scale), providing sufficient margin relative to the output threshold intensity.

[0044] Since such a signal theoretically has a margin that can be amplified by at least 2 times (6 dB), the electronic device (100) can change the volume table (10) of the system to match the target performance curve (11) so that the output strength becomes 6 dB when the output volume level is 100.

[0045] However, when the input signal strength is close to 0 dBFS, simply amplifying the input signal can cause an overflow that exceeds the system's output boundary strength, resulting in sound quality distortion. Therefore, when the input signal strength is close to 0 dBFS, techniques to compress the input signal to secure a margin have been utilized.

[0046] However, in this case, there was a problem in that the volume amplification effect at high volume levels was reduced due to sound pressure loss caused by compressing input signals above the threshold.

[0047] Below, various embodiments capable of enhancing the volume amplification effect at high output volume levels will be described.

[0048] FIG. 2 is a block diagram for explaining the configuration of an electronic device according to one embodiment of the present disclosure.

[0049] Referring to FIG. 2, the electronic device (100) may include an audio output unit (110) and a processor (120). The electronic device (100) may be implemented as a TV, speaker unit, wired / wireless speaker, PC, wired / wireless earphones, headset, smartphone, etc., and may also be implemented as various other devices capable of outputting an audio signal.

[0050] The audio output unit (110) is configured to audibly output an audio signal.

[0051] The audio output unit (110) may be implemented as a speaker. The speaker may include a coil and a diaphragm that vibrate under the influence of a magnetic field generated by an electric current. Additionally, the speaker may include an amplifier that amplifies an electrical signal. At this time, it goes without saying that the amplifier (not shown) may be included in the audio output unit (110) as a separate component from the speaker.

[0052] Since the audio output unit (110) includes a coil, a diaphragm, an amplifier, etc., the output strength of the audio output unit (110) is inevitably limited depending on the performance of the components within the electronic device (100) and the size of the space where the audio output unit (110) is installed.

[0053] The processor (120) controls the overall operation of the electronic device (100).

[0054] Specifically, the processor (120) is connected to each component of the electronic device (100) to control the overall operation of the electronic device (100). For example, the processor (120) is connected to the audio output unit (110) to control the operation of the electronic device (100).

[0055] According to one embodiment, the processor (120) may be named by various names such as a digital signal processor (DSP), a microprocessor, a central processing unit (CPU), a Micro Controller Unit (MCU), a micro processing unit (MPU), a Neural Processing Unit (NPU), a controller, or an application processor (AP), but in this specification, it is referred to as a processor (120). The processor (120) may be implemented as a System on Chip (SoC) or a Large Scale Integration (LSI), or may be implemented in the form of a Field Programmable Gate Array (FPGA). Additionally, the processor (120) may include volatile memory such as SRAM.

[0056] A processor (120) according to one embodiment can scale an input audio signal based on a volume level when an audio signal is input, and if the volume level is greater than or equal to a first threshold level, apply a first gain to the scaled audio signal to adjust the strength of the scaled audio signal.

[0057] Here, the first gain can be applied to horizontally expand the waveform of the input audio signal. The first gain can be applied only when the output volume level is above the first threshold level to solve the problem where the perceived volume increase effect is reduced due to sound pressure loss caused by compression at high volume levels.

[0058] Here, the first threshold level may be arbitrarily set by the user, but may be stored in memory (not shown) included in the electronic device (100) or input to the electronic device (100) from the outside.

[0059] Specifically, when the components of the audio signal input to the electronic device (100) are mostly so-called Peak-2-Peak input signals corresponding to the limiting output strength of the electronic device, the first threshold level can be set so that there is no audio signal having a strength greater than the threshold strength to which the second gain, which will be described later, is applied at the corresponding output volume level.

[0060] For example, in the range where the volume level is above the first threshold level and below the maximum volume level, the strength of the audio signal to which the first gain is applied can be adjusted in the form of a third function.

[0061] For example, when the output volume level is at maximum, the processor (120) can adjust the strength of the audio signal based on the following mathematical formula 1 when applying the first gain.

[0062] [Mathematical Formula 1]

[0063] y = (1+β)*x - β*x^3

[0064] Here, x is the strength of the input audio signal, y is the strength of the output audio signal, and β can be a positive number less than or equal to 0.5.

[0065] Additionally, the first gain can be determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after adjustment.

[0066] Next, the processor (120) can control the audio output unit (110) to apply a second gain to the adjusted audio signal when the strength of the adjusted audio signal is greater than or equal to the threshold strength, thereby readjusting the strength of the adjusted audio signal and amplifying the readjusted audio signal to output it.

[0067] Here, the second gain may be applied to compress a signal having a strength greater than or equal to a threshold strength among the audio signals adjusted by applying the first gain. Specifically, the second gain may be applied to solve the problem of the input signal being saturated at 0 dBFS while the electronic device (100) amplifies the audio signal.

[0068] For example, an electronic device (100) can reduce an input audio signal having a strength greater than a threshold strength by a specific Reduction Level. In this case, the Reduction Level may be a preset value.

[0069] Here, the threshold is a preset value, and the threshold may be arbitrarily set by the user, but may also be stored in a memory (not shown) included in the electronic device (100) or input to the electronic device (100) from the outside.

[0070] Here, the processor (120) can adjust the strength of the applied audio signal by applying a third gain to the scaled audio signal if the volume level is above a second threshold level, and applying a first gain to the audio signal to which the third gain has been applied if the volume level is above a first threshold level. In this case, the second threshold level may be lower than the first threshold level.

[0071] A third gain can be applied to more efficiently improve the problem of reduced perceived volume increase due to sound pressure loss at high volume levels.

[0072] Specifically, a third gain may be applied to compensate for the reduction in input signal strength caused by equalization according to one embodiment of the present disclosure.

[0073] For example, when the output volume level is 50 and a reduction in input signal strength due to equalization occurs, the third gain may be applied when the output volume level is 50 or higher, and in this case, the second threshold level becomes 50.

[0074] Meanwhile, it does not matter if the second threshold level has a value greater than the first threshold level.

[0075] Here, the second threshold level can be determined by the characteristics of the Tone Mapping Curve (TMC). Specifically, the TMC can divide the audio signal into multiple frequency bands and equalize the audio signal of each of the multiple frequency bands based on the output volume level.

[0076] Here, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain may be in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain may be in the form of a linearly decreasing function.

[0077] Additionally, the processor (120) may maintain the strength of the adjusted audio signal if the strength of the adjusted audio signal is below a threshold strength, and may readjust the strength of the adjusted audio signal by applying a second gain to the adjusted audio signal if the strength of the adjusted audio signal is above a threshold strength. In this case, the strength of the audio signal after readjustment above a threshold strength may be reduced compared to the strength of the audio signal before readjustment.

[0078] Specifically, by reducing only audio signals above a threshold strength, the electronic device (100) can improve the saturation problem for signals close to 0 dBFS and obtain an effective volume increase effect.

[0079] Meanwhile, the processor (120) can preprocess the scaled audio signal by applying a fourth gain to the scaled audio signal if the strength of the scaled audio signal is greater than or equal to a threshold strength, and can adjust the strength of the preprocessed audio signal by applying a first gain to the preprocessed audio signal.

[0080] Here, the fourth gain, like the second gain, can be applied to compress a signal having a strength greater than or equal to a threshold strength among audio signals. Specifically, the fourth gain can be applied to solve the problem of an input signal close to 0 dBFS becoming saturated while the electronic device (100) amplifies the audio signal.

[0081] Meanwhile, the reason for applying the 4th gain separately from the 2nd gain is that it places less computational burden on the hardware than compressing the input audio signal all at once, and the degradation of the output signal's sound quality can be improved through two rounds of softclipping.

[0082] Here, the threshold strength may be the same value as the threshold strength when applying the second gain, but is not necessarily limited to this.

[0083] FIG. 3 is a block diagram illustrating the functional configuration of an electronic device according to one embodiment of the present disclosure.

[0084] Referring to FIG. 3, the electronic device (100) may include a Scaling module (310) and an Amplifier module (320). Each of these modules may be a software module stored in the memory of the electronic device (100) or a hardware module circuitously implemented on the electronic device (100). Alternatively, each of these modules may be implemented in a combined form of software and hardware.

[0085] Below, the above-described modules will be described on the premise that they perform operations having the functions of the processor (120) described in FIG. 2.

[0086] The electronic device (100) can scale the audio signal based on the output volume level volume through the Scaling module (310).

[0087] At this time, the audio signal may be stored in memory (not shown) of the electronic device (100) or received from an external source.

[0088] The processor (120) can amplify the scaled audio signal through the amplifier module (320). Specifically, the processor (120) can control the audio output unit (110) to output the audio signal amplified by the amplifier module (320).

[0089] The degree to which the signal strength of the audio signal is amplified through the amplifier module (320) can be determined by the output volume and a preset Look-Up Table (305). The Look-Up Table (305) may be stored in memory (not shown) or calculated according to real-time calculations of the electronic device (100).

[0090] Here, the Look-Up-Table (305) refers to a set (array) of pre-calculated results for a given operation. This set (array) is used as a reference to retrieve values ​​faster than the time it takes to calculate the result for the given operation.

[0091] Specifically, the Look-Up-Table (305) is used in a real-time processing system (embedded system) where there is a high need to obtain the result of the calculation within a time.

[0092] Referring to FIG. 3, the amplifier module (320) may include a compressor (321) and a makeup module (322).

[0093] The compressor (321) can readjust the strength of the scaled audio signal. Here, readjustment refers to the operation of reducing the strength of an audio signal by applying a second gain to an audio signal whose strength is greater than or equal to a preset threshold strength, and for convenience of explanation, it will be referred to as compression below.

[0094] Figures 4a and 4b illustrate the compression process of a scaled audio signal.

[0095] If the audio signal that has passed through the Scaling module (310) does not pass through the Amplifier module (320), the audio signal can be output through the audio output unit (110) with a signal strength (: Output Level, 410 in FIG. 4a) equal to the signal strength (: Input Level) of the scaled state.

[0096] Referring to FIG. 4b, the compressor (321) reduces the signal strength of audio signals whose signal strength (: Input Level) is greater than or equal to the threshold (405), while maintaining the signal strength of audio signals whose signal strength is less than the threshold (405). As a result, a compressed audio signal (420) having a compressed signal strength can be obtained. Here, the threshold (405) may be a preset value according to the LUT (305).

[0097] Referring to FIGS. 4a and 4b, when an audio signal is compressed, the maximum signal strength of the audio signal can be changed (401 -> 402) by a specific Reduction Level (403). At this time, the Reduction Level (403) may be a preset value according to the LUT (305).

[0098] The Makeup module (322) can amplify the compressed audio signal. Specifically, the Makeup module (322) can amplify the compressed audio signal by increasing the signal strength of the entire compressed audio signal within a range that does not exceed the maximum output strength of the audio output unit (110).

[0099] Specifically, referring to FIG. 4c, the Makeup module (322) can amplify the compressed audio signal (420) with respect to the total signal strength. As a result, an amplified audio signal (430) having increased signal strength can be obtained.

[0100] Referring to FIG. 4c, it can be seen that the maximum output strength of the audio signal has increased back to the level before compression (: 401). That is, as a result of compression by the Compressor module (321) and amplification by the Makeup module (322), the maximum signal strength of the audio signal is maintained, but the signal strength of the audio signal can be increased for all other signal strengths.

[0101] FIGS. 5a to 5c are drawings for illustrating an example of compressing and amplifying an audio signal according to one embodiment of the present disclosure.

[0102] FIG. 5a illustrates the signal strength of the resulting audio signal (510) scaled based on a maximum volume (e.g., volume level 100) according to one example, whereby the strength of the audio signal (510) at a specific point in time may correspond to the maximum output strength (501) of the audio output unit (110).

[0103] FIG. 5b illustrates a state in which an audio signal (510) is compressed, for example, an audio signal whose signal strength exceeds a threshold strength (505) may be compressed. As a result, the maximum signal strength of the compressed audio signal (520) is reduced (501 -> 502), and a margin (503) that did not exist before may be created.

[0104] Here, the margin is the difference between the maximum signal strength of the audio signal and the maximum output strength of the audio output unit (110).

[0105] According to one embodiment, when considering the problem of saturation during audio signal amplification, the electronic device (100) can amplify the audio signal in proportion to the size of the margin.

[0106] FIG. 5c illustrates an amplified state of the audio signal (520) of FIG. 5b, wherein the signal strength of the audio signal (520) can be increased overall within a range that does not exceed the maximum output strength.

[0107] Referring to FIG. 5c, the maximum signal strength of the audio signal before and after amplification of the audio signal (520), that is, before and after passing through the amplifier module (320), is the same, but as a result of the overall increase in the signal strength of the compressed and amplified audio signal (530) compared to the existing audio signal (510), the loudness or perceived volume can be greatly improved.

[0108] Since the user's perceived volume, i.e., loudness, is proportional to the area occupied by the audio signal in the time domain, the electronic device (100) according to one embodiment of the present disclosure can provide the user with an increased volume without adjusting the maximum signal strength of the audio signal.

[0109] Meanwhile, unlike FIGS. 5a to 5c which illustrate cases where the output volume level is at its maximum, if the input audio signal is -24 dB LKFS rather than 0 dBFS or if the output volume level is not at its maximum, there is already a margin between the maximum signal strength of the scaled audio signal and the maximum output strength of the audio output unit (110), so the Compressor (321) does not need to compress the input audio signal.

[0110] Specifically, when the input audio signal is -24 dB LKFS rather than 0 dBFS or when the output volume level is not at maximum, there is bound to be a large proportion of input signals with a maximum signal strength lower than the threshold strength (505), similar to the low-intensity input signal (540) shown in FIG. 5a.

[0111] Therefore, in this case, since the strength of the audio signal is simply amplified without compression by the Compressor (321) (550), a volume increase effect proportional to the gain of the makeup module (322) can be expected without sound pressure loss due to compression.

[0112] On the other hand, when the input audio signal is 0 dBFS, the proportion of the input signal having a maximum value exceeding the threshold strength (505) at a high volume level increases, so sound pressure loss due to compression occurs, and the volume is increased at a rate smaller than the gain of the makeup module (322).

[0113] As described above, in order to improve the reduction of the volume amplification effect at high volume levels when the input audio signal is 0dBFS, the electronic device (100) needs to be equipped with a new component.

[0114] FIG. 6 is a block diagram illustrating the basic configuration of an amplifier (320) according to one embodiment of the present disclosure.

[0115] An amplifier (320) according to one embodiment of the present disclosure is composed of a DRC1 (Dynamic Range Control, 321-1), a Tone Mapping Curve (TMC, 610), an Overdriver (620), an Expander (630), a DRC2 (321-2), and a Makeup (322), having the same function as the Compressor (321) described in FIG. 3.

[0116] DRC (321-1, 321-2) is a configuration that performs the same operation as Compressor (321), reducing the signal strength of audio signals whose signal strength is above a threshold strength, while maintaining the signal strength of audio signals whose signal strength is below a threshold strength.

[0117] The reason two DRCs (321-1, 321-2) are provided is that the computational burden on the hardware is less than compressing the input audio signal all at once, and the degradation of the output signal's sound quality can be improved through two softclipping steps.

[0118] According to one embodiment of the present disclosure, DRC2 (321-2) is an essential component, but DRC1 (321-1) may be an optional component.

[0119] Referring to FIG. 7, the TMC (610) may be configured as an equalizer, for example. An equalizer is generally configured to simply amplify low and high frequencies, taking into account human auditory characteristics, but the TMC module according to the present disclosure can adjust the signal strength by frequency according to the output volume level.

[0120] FIG. 7 is a graph illustrating the operation of a TMC (610) that relatively adjusts the signal strength by frequency of an audio signal compressed by DRC1 (321-1).

[0121] The TMC (610) can equalize the compressed audio signal by dividing the compressed audio signal into multiple frequency bands and adjusting the signal strength of each of the multiple frequency bands based on the output volume level.

[0122] Referring to FIG. 7, the compressed audio signal can be divided into a first frequency band (710), a second frequency band (720) higher than the first frequency band (710), and a third frequency band (730) higher than the second frequency band (720).

[0123] As a result of providing a TMC (610) according to one embodiment of the present disclosure, the electronic device (100) can compensate for human hearing characteristics such that the low frequency range (710) and high frequency range (730) of a low-volume audio signal are relatively difficult to hear compared to the mid-range (720), and the low frequency range (710) and high frequency range (730) of a high-volume audio signal are relatively difficult to hear compared to the mid-range (720).

[0124] Meanwhile, referring to FIG. 7, the TMC (610) according to one embodiment of the present disclosure can reduce the signal strength of the audio signal overall when the output volume level becomes higher than 50. Due to the characteristic of the TMC (610) reducing the signal strength of the input audio signal overall above the threshold volume level, a reduction in the loudness increase effect perceived by the user at high volume levels may occur, and the electronic device (100) may be equipped with an Overdriver (620) to compensate for this.

[0125] The overdriver (620) linearly amplifies the input signal and complements the operation of the expander (630) located in the next stage, thereby appropriately adjusting the target performance to be achieved in the present invention.

[0126] Specifically, the third gain can be determined according to the characteristics of the Overdriver (620).

[0127] FIG. 8a is a graph showing the change in the third gain, which is a characteristic of the Overdriver (620) for the output volume level according to one embodiment of the present disclosure.

[0128] According to one embodiment of the present disclosure, the third gain increases at an inflection point (volume: 50, 810) where the frequency component of the input signal begins to decrease overall by the TMC (610). To compensate for the decrease in the strength of the audio input signal by the TMC (610), the third gain according to one embodiment may increase linearly until the output volume level reaches its maximum.

[0129] In FIG. 8a, it is shown that when the volume level is 100, the third gain can have a value of 2.5, but this is merely an example, and the maximum value of the third gain can be set to any other value.

[0130] The Expander (630) is configured to expand the waveform of the input audio signal, and can improve the effect of increasing the perceived volume by expanding the signal waveform to the left and right by applying the first gain described above.

[0131] FIG. 8b is a graph showing the change in delta (β) value involved in the output characteristics of an expander with respect to an output volume level according to one embodiment of the present disclosure.

[0132] An Expander (630) according to one embodiment of the present disclosure can adjust the strength of an audio signal based on Equation 1 as above when the volume level is at its maximum.

[0133] Referring to FIG. 9, when the output volume level is at maximum (volume: 100), the strength of the input signal has a maximum value of 0dB (x = 1) without strength reduction due to scaling.

[0134] For example, when the delta value is 0, the input signal is output as is without change in intensity (910).

[0135] Meanwhile, according to one embodiment of the present disclosure, as the delta value increases, the output characteristics of the Expander (630) are represented as an upwardly convex graph.

[0136] In particular, when delta has a value of 0.5, which is the maximum value according to one embodiment of the present disclosure, the graph (940) has a shape that rises to the maximum.

[0137] Referring to FIG. 10, the waveform of an input audio signal (1010) can be expanded horizontally (1020) by the operation of an Expander (630) according to one embodiment of the present disclosure, so that the area occupied by the sound wave can be increased.

[0138] In this case, the loudness perceived by the user can be improved without changing the maximum value of the input audio signal, and accordingly, the Expander (630) can improve the reduction in the perceived volume increase effect caused by the limitation of securing a margin for Amplitude in the conventional technology.

[0139] Referring again to FIG. 8b, since the larger the delta value, the louder the user perceives the volume, the Expander (630) according to one embodiment of the present disclosure may have a delta value that increases linearly from the point (820) where the volume level becomes 50.

[0140] In FIG. 8b, the volume level at the point (820) where the delta value increases is assumed to be 50, but this is merely an example and may have any other value depending on the implementation method of the electronic device (100).

[0141] As described in FIGS. 8a and 8b, the effect of reducing the perceived volume increase effect at high volume levels can be partially improved through the increase in the third gain and the increase in the delta value of the Expander (630).

[0142] FIGS. 11a and 11b are drawings for explaining that, for each of the Peak-2-Peak input signal and -24dB LKFS input signal, the effect of increasing perceived volume at high volume levels is improved by the operation of the Overdriver (620) and Expander (630) described in FIGS. 8a and 8b.

[0143] Referring to FIG. 11a, the volume table characteristics according to the conventional method of increasing volume are shown (12). As previously explained, in the case of the so-called Peak-2-Peak input signal, where the components of the input audio signal mostly correspond to the limiting output strength of the electronic device, compression by DRC (321) is required at a high volume level, so it can be seen that there is a problem in that the perceived volume increase effect is reduced with increasing volume.

[0144] In accordance with one embodiment of the present disclosure, the sound pressure increase effect at a high volume level is improved by the operation of the Overdriver (620) and Expander (630), so that the volume table characteristic (13-1) can approach the target performance (11) of the electronic device (100).

[0145] However, as exemplified in Figures 8a and 8b, for -24dB LKFS input signals, a problem may arise where the volume table characteristics are excessively corrected.

[0146] Referring to FIG. 11b, it can be seen that the output (14-1) of the electronic device (100) for a -24dB LKFS input signal has increased excessively beyond the target performance (11).

[0147] This is a phenomenon that occurs because the DRC (321) does not compress the input signal, as the -24dB LKFS input signal has sufficient output margin relative to the strength of the input signal. As a result, one embodiment of the present disclosure may be an undesirable embodiment in which the perceived volume increase effect at high volume levels is distorted more than necessary.

[0148] Therefore, in order to improve the problem of the output characteristics of the -24dB LKFS input signal being distorted in one embodiment of the present disclosure, it is necessary to appropriately adjust the characteristics of the Overdriver (620) and the Expander (630).

[0149] FIG. 12a is a graph showing the change in a third gain for an output volume level according to another embodiment of the present disclosure.

[0150] FIG. 12b is a graph showing the change in delta (β) value involved in the output characteristics of an expander with respect to an output volume level according to another embodiment of the present disclosure.

[0151] Referring to FIG. 12a, the third gain according to another embodiment of the present disclosure rises at an inflection point (volume: 50, 1210) where the frequency component of the input signal begins to decrease overall by the TMC (610) (1211), which is common to FIG. 8a.

[0152] However, according to another embodiment of the present disclosure, the third gain may decrease from the volume level (75) where the Expander (630) after the Overdriver (620) operates (1212).

[0153] In FIG. 12a, the third gain is shown to have a maximum value of 1.5 at the volume level (75) where the Expander (630) is operating, but this is merely an example, and the maximum value of the third gain can be set to any other value.

[0154] Referring to FIG. 12b, the delta value of the Expander (630) according to another embodiment of the present disclosure may have a positive value that increases linearly starting from the point (1220) where the volume level is 75.

[0155] In FIG. 12b, the volume level at the point (1220) where the delta value increases is assumed to be 75, but this is merely an example and may have any other value depending on the implementation method of the electronic device (100).

[0156] Referring to FIG. 13a, it can be seen that the output characteristics (13-2) of the electronic device (100) for a Peak-2-Peak input signal according to another embodiment of the present disclosure are improved compared to the prior art (12) at a high volume level.

[0157] In another embodiment of the present disclosure, the problem of volume table characteristics being excessively corrected for a -24db LKFS input signal, as described above, can also be improved.

[0158] Referring to FIG. 13b, since the third gain value decreases from the point (1220) where the Expander (630) starts operating, the output characteristics (14-2) at high volume levels are not excessively corrected.

[0159] As described in other embodiments of the present disclosure, the electronic device (100) can have output characteristics close to the target performance (11) for both Peak-2-Peak and -24dB LKFS input signals by appropriately setting the characteristics of the Overdriver (620) and Expander (630).

[0160] FIG. 14 is a block diagram for specifically explaining the functional configuration of an electronic device according to one embodiment of the present disclosure.

[0161] Referring to FIG. 14, the electronic device (100') may further include at least one of a communication unit (130), a broadcast receiving unit (140), a memory (150), and a user input unit (160) in addition to the audio output unit (110) and the processor (120).

[0162] The communication unit (130) is configured for the electronic device (100') to communicate with at least one external device to receive an audio signal. To this end, the communication unit (130) circuit may be included.

[0163] The communication unit (130) may include a wireless communication module, a wired communication module, etc.

[0164] The wireless communication module may include at least one of a Wi-Fi communication module, a Bluetooth module, an infrared communication (IrDA, infrared data association) module, a 3G (3rd generation) mobile communication module, a 4G (4th generation) mobile communication module, a 4th generation LTE (Long Term Evolution) communication module, and a 5G (5th generation) communication module to receive content from an external server or external device.

[0165] The wired communication module can be implemented as a wired port such as a Thunderbolt port or a USB port.

[0166] The communication unit (130) can receive information regarding user input received from a remote control device (not shown), etc. In this case, the processor (120) can set an output volume level or set a mode of the electronic device (100') through the received information. In this case, the communication unit (130) can communicate with the remote control device through a Bluetooth module, etc.

[0167] The broadcast receiver (140) can receive a signal for broadcast content. The broadcast content may include video, audio, and additional data (e.g., EPG), and the broadcast receiver (140) can receive broadcast content signals from various sources such as terrestrial broadcasting, cable broadcasting, satellite broadcasting, internet broadcasting, etc.

[0168] The broadcast receiver (140) may be implemented in a form including a tuner (not shown), a demodulator (not shown), an equalizer (not shown), etc., to receive broadcast content transmitted from a broadcasting station.

[0169] The processor (120) can perform scaling and amplification on the audio signal among the content received through the broadcast receiver (140) and output it through the audio output unit (110).

[0170] The memory (150) is configured to store an operating system (OS) for controlling the overall operation of the components of the electronic device (100') and commands or data related to the components of the electronic device (100').

[0171] To this end, the memory (150) can be implemented as non-volatile memory (e.g., hard disk, SSD (Solid state drive), flash memory), volatile memory, etc.

[0172] In the memory (150), various modules described above according to the present disclosure may be stored in the form of software.

[0173] A Look-up Table (LUT) for the operation of the Amplifier (320) may be stored in the memory (150).

[0174] The user input section (160) is configured to enable the electronic device (100') to receive commands or information from the user.

[0175] The user input unit (160) may include a touch panel (not shown) implemented together with a display (not shown) or a separate touch pad (not shown) to receive user commands or information by touch. The user input unit (160) may also include a microphone (not shown) to receive user commands or information by voice.

[0176] The user input unit (160) may include one or more buttons, a keyboard, a mouse (not shown above) to receive information from the user.

[0177] The processor (120) can set the output volume level or the mode of the electronic device (100') according to user input received through the user input unit (160).

[0178] A method for controlling an electronic device according to the present disclosure will be explained below through FIGS. 15 and 16.

[0179] FIG. 15 is a flowchart for explaining a method of controlling an electronic device according to one embodiment of the present disclosure.

[0180] Referring to FIG. 15, the control method can scale the audio signal based on the volume level entered by the user when an audio signal is input (S1510).

[0181] And, if the volume level is above the first threshold level, the strength of the scaled audio signal can be adjusted by applying the first gain to the scaled audio signal (S1520).

[0182] Next, if the strength of the adjusted audio signal is greater than or equal to the threshold strength, a second gain can be applied to the adjusted audio signal to readjust the strength of the adjusted audio signal (S1530).

[0183] And, the readjusted audio signal can be amplified (S1540), and then the amplified audio signal can be output (S1550).

[0184] Here, in the interval where the volume level is above the first threshold level and below the maximum volume level, the strength of the audio signal to which the first gain is applied can be adjusted in the form of a cubic function.

[0185] Here, the step (S1520) of adjusting the strength of the scaled audio signal by applying the first gain can adjust the strength of the audio signal based on Equation 1 as described above.

[0186] Meanwhile, the first gain can be determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after adjustment.

[0187] Additionally, if the volume level is above the second threshold level, a third gain can be applied to the scaled audio signal. And, if the volume level is above the first threshold level, the strength of the audio signal can be adjusted by applying a first gain to the audio signal to which the third gain has been applied.

[0188] Here, the second threshold level may be lower than the first threshold level.

[0189] Meanwhile, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain may be in the form of a linearly increasing function. Additionally, in the interval where the volume level is above the first threshold level and below the maximum level, the third gain may be in the form of a linearly decreasing function.

[0190] Specifically, the second critical level can be determined by the characteristics of the Tone Mapping Curve (TMC).

[0191] Meanwhile, the step of readjusting the strength of the adjusted audio signal (S1530) can maintain the strength of the adjusted audio signal if the strength of the adjusted audio signal is below a threshold strength, and readjust the strength of the adjusted audio signal by applying a second gain to the adjusted audio signal if the strength of the adjusted audio signal is above a threshold strength.

[0192] Also, above the threshold strength, the strength of the audio signal after readjustment may decrease compared to the strength of the audio signal before readjustment.

[0193] Additionally, a control method according to one embodiment of the present disclosure may further include a step of preprocessing a scaled audio signal by applying a fourth gain to the scaled audio signal when the intensity of the scaled audio signal is greater than or equal to a threshold intensity.

[0194] FIG. 16 is a flowchart illustrating a control method for an electronic device that performs two signal compressions and equalizations according to one embodiment of the present disclosure.

[0195] Referring to FIG. 16, the control method can perform scaling, adjustment, and re-adjustment on an input audio signal, similar to S1510 to S1550 of FIG. 15 (S1610, S1640 to S1650).

[0196] A control method according to one embodiment of the present disclosure may include a step (S1620) of preprocessing by applying a fourth gain to a scaled signal after the audio signal has been scaled (S1610).

[0197] Preprocessing by applying the fourth gain in this way is intended to minimize the degradation of the sound quality of the output signal by soft-clipping the input signal before readjusting the adjusted audio signal (S1650).

[0198] And, equalization can be performed on the preprocessed audio signal (S1630).

[0199] Specifically, the preprocessed audio signal can be equalized by dividing it into multiple frequency bands and adjusting the signal strength of each audio signal in the multiple frequency bands based on the output volume level.

[0200] Next, the signal strength can be adjusted by applying a first gain to the equalized audio signal (S1640).

[0201] In addition, the control method can readjust the audio signal by reducing the signal strength of the audio signal among the adjusted audio signals, such that the signal strength is greater than or equal to a preset threshold strength (S1650).

[0202] And, within a range that does not exceed the maximum output strength, the signal strength of the entire re-adjusted audio signal can be increased to amplify the re-adjusted audio signal (S1660).

[0203] And, an amplified audio signal can be output (S1670).

[0204] Meanwhile, the control method illustrated and described through FIGS. 15 and 16 can be implemented through the electronic device (100) illustrated and described through FIGS. 2 and 14.

[0205] Alternatively, the control method illustrated and described through FIGS. 15 and 16 may be implemented through a system comprising an electronic device (100) and one or more external devices.

[0206] Meanwhile, the various embodiments described above may be implemented in a recording medium readable by a computer or a similar device using software, hardware, or a combination thereof.

[0207] According to hardware implementation, the embodiments described in this disclosure may be implemented using at least one of ASICs (Application Specific Integrated Circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (Programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and other electrical units for performing functions.

[0208] In some cases, the embodiments described herein may be implemented in the processor (120) itself. In a software implementation, embodiments such as the procedures and functions described herein may be implemented in separate software modules. Each of the aforementioned software modules may perform one or more functions and operations described herein.

[0209] Meanwhile, computer instructions for performing processing operations in an electronic device (100) according to various embodiments of the present disclosure described above may be stored in a non-transitory computer-readable medium. When computer instructions stored in such a non-transitory computer-readable medium are executed by a processor of a specific device, the specific device described above performs processing operations of the electronic device (100) according to various embodiments described above.

[0210] A non-transient readable medium refers to a medium that stores data semi-permanently and can be read by a device, rather than a medium that stores data for a short period of time, such as a register, cache, or memory. Specifically, the various applications or programs described above may be stored and provided on non-transient readable media such as CDs, DVDs, hard disks, Blu-ray discs, USBs, memory cards, and ROMs.

[0211] Furthermore, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0212] 100: Electronic device 110: Audio output section 120: Processor 130: Communication unit 140: Broadcast receiver 150: Memory 160: User Input Section

Claims

Claim 1 Audio output section; A processor that controls an audio output unit to output an amplified audio signal, wherein when an audio signal is input, the input audio signal is scaled based on a volume level, and if the volume level is below a first threshold level but above a second threshold level, a third gain is applied to the scaled audio signal, and if the volume level is above the first threshold level, a first gain is applied to the audio signal to adjust the strength of the scaled audio signal, and if the strength of the adjusted audio signal is below a threshold level, the strength of the adjusted audio signal is maintained, and if the strength of the adjusted audio signal is above a threshold level, a second gain is applied to the adjusted audio signal to readjust the strength of the adjusted audio signal, and the audio output unit is controlled to amplify the readjusted audio signal. In the interval where the volume level is above the second threshold level and below the first threshold level, the third gain is in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain is in the form of a linearly decreasing function, and when the volume level is above the first threshold level and above the maximum An electronic device in which the strength of the adjusted audio signal in the section below the volume level is in the form of a cubic function, the strength of the audio signal after readjustment above the threshold strength is reduced compared to the strength of the audio signal before readjustment, and the first gain is determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after the readjustment. Claim 2 delete Claim 3 In claim 1, the processor is an electronic device that adjusts the strength of the audio signal based on the following mathematical formula when the volume level is at its maximum: y = (1+β)*x - β*x^3, where x is the strength of the input audio signal, y is the strength of the output audio signal, and β is a positive number less than or equal to 0.

5. Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 A method for controlling an electronic device comprises: a step of scaling the audio signal based on a volume level input by a user when an audio signal is input; a step of applying a third gain to the scaled audio signal if the volume level is a level below a first threshold level and is greater than or equal to a second threshold level; a step of adjusting the intensity of the scaled audio signal by applying a first gain to the audio signal to which the third gain has been applied if the volume level is greater than or equal to the first threshold level; a step of maintaining the intensity of the adjusted audio signal if the intensity of the adjusted audio signal is less than or equal to a threshold intensity, and re-adjusting the intensity of the adjusted audio signal by applying a second gain to the adjusted audio signal if the intensity of the adjusted audio signal is greater than or equal to a threshold intensity. A control method comprising the step of amplifying and outputting the re-adjusted audio signal; wherein, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain is in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain is in the form of a linearly decreasing function, and in the interval where the volume level is above the first threshold level and below the maximum volume level, the strength of the adjusted audio signal is in the form of a cubic function, and above the threshold strength, the strength of the audio signal after re-adjustment is reduced compared to the strength of the audio signal before re-adjustment, and the first gain is determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after the adjustment. Claim 10 A non-transient computer-readable medium storing computer instructions that cause said electronic device to perform an operation when executed by a processor of said electronic device, wherein the operation comprises: a step of scaling said audio signal based on a volume level when an audio signal is input; a step of applying a third gain to said audio signal if said volume level is a level below a first threshold level and is greater than or equal to a second threshold level; a step of adjusting the strength of said scaled audio signal by applying a first gain to said audio signal to which the third gain has been applied if said volume level is greater than or equal to the first threshold level; and a step of maintaining the strength of said adjusted audio signal if said strength of said adjusted audio signal is less than or equal to a threshold strength, and re-adjusting the strength of said adjusted audio signal by applying a second gain to said adjusted audio signal if said strength of said adjusted audio signal is greater than or equal to a threshold strength. A non-transient computer-readable medium comprising the step of amplifying and outputting the re-adjusted audio signal; wherein, in the interval where the volume level is above the second threshold level and below the first threshold level, the third gain is in the form of a linearly increasing function, and in the interval where the volume level is above the first threshold level and below the maximum level, the third gain is in the form of a linearly decreasing function, and in the interval where the volume level is above the first threshold level and below the maximum volume level, the strength of the adjusted audio signal is in the form of a cubic function, and above the threshold strength, the strength of the audio signal after re-adjustment is reduced compared to the strength of the audio signal before re-adjustment, and the first gain is determined such that the strength of the audio signal having the maximum strength among the scaled audio signals is maintained even after the adjustment. Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete

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