Method and electronic device for adjusting the balance of an audio signal

Abstract

Procedure comprehensive: Determining an audio noise spectrum (F noise ), which represents external audio noise, Determining an audio reference spectrum (F ref ), which represents audio content to be perceived by a listener, Determining a compensation spectrum (35) based on the audio noise spectrum (F noise ) and based on the audio reference spectrum (F ref ), in which determining the compensation spectrum (35) involves subtracting the audio reference spectrum (F ref ) from the audio noise spectrum (F noise ) includes, and Balancing an audio source signal (37) according to the compensation spectrum (35).

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of audio equalization, and more particularly to methods and apparatus for adjusting the balance between frequency components of an audio signal. TECHNICAL BACKGROUND

[0002] When listening to audio content such as music through headphones, for example, noise (or hiss) in the listener's environment influences the sonic impression of the material. This external noise can mask the perception of the musical material.

[0003] When listening to audio from a music player with headphones, the sound may be perfect in a listening environment with little or no external noise. However, in a noisy environment (e.g., a train), the sound experience through headphones will be degraded due to the auditory masking effect. Low frequencies below the threshold of external noise will not be clearly audible. The headphones will sound as if they no longer deliver any frequencies below a certain low frequency. This results in the perception of degraded bass.

[0004] Active noise control, also known as noise suppression or active noise cancellation, is a method for reducing unwanted sounds by adding other sounds introduced to cancel out the unwanted sounds. Active noise compensation is typically implemented using analog circuits or digital signal processing. Adaptive algorithms are designed to analyze the waveform of the background noise. A signal is then generated that either shifts or inverts the polarity of the original signal.

[0005] However, noise cancellation requires a loudspeaker colocated with the sound source to be attenuated. Furthermore, state-of-the-art active noise cancellation systems impair the perception of low frequencies.

[0006] Although techniques for active noise compensation exist, it is generally desirable to provide alternative methods and devices for noise control.

[0007] US 2009 / 0 323 976 A1 discloses an active noise control in which an audio signal for noise reduction is generated from a recorded ambient audio signal, wherein an audio component extracted from the ambient audio signal, which is to be preserved, is reproduced and played back.

[0008] US 2009 / 0 034 747 A1 discloses a system and method for improving the audio signal generated by an audio system in a listening environment by compensating for ambient noise in the listening environment. For this purpose, an electrical audio sound signal in the time domain is converted into an electrical audio sound signal in the frequency domain. Furthermore, the overall sound level in the environment is measured, and a signal representative thereof is generated. The audio sound signal and the overall sound signal are processed to extract a signal representing the ambient noise level in the environment, and frequency-domain equalization is performed to adjust the output of the audio sound signal so that the ambient noise level is compensated.

[0009] US 2005 / 0 063 552 A1 discloses a system and method for ambient noise compensation. The system comprises a variable amplifier, a source sound processor, an area sound processor, and an adjustment circuit. The variable amplifier adjusts an audio input signal to produce an audio output signal at an appropriate level so that the audio output signal is audible above the noise in a listening area. The source sound processor and the area sound processor can divide the audio output signal and a monitoring signal into frequency bands and compare these signals band by band to find differences representing time-varying noise in the monitoring signal. These differences can be modified to account for the acoustic response of the listening area and background noise with a constant level in the listening area. The adjustment circuit controls the variable amplifier depending on these differences. SUMMARY

[0010] According to a first solution, the present invention provides a method according to independent claim 1. According to a second solution, the present invention provides an electronic device according to independent claim 10. According to a third solution, the present invention provides a computer program according to claim 13. Further aspects of the invention are set out in the dependent claims, the figures, and the following description.

[0011] According to a first aspect, the disclosure provides a method comprising determining an audio noise spectrum representing external audio noise, determining an audio reference spectrum representing audio content to be perceived by a listener, and determining a compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum.

[0012] According to a further aspect, the disclosure provides an electronic device comprising a noise spectrum determination unit configured to determine an audio noise spectrum representing external audio noise, a reference spectrum determination unit configured to determine an audio reference spectrum representing audio content to be perceived by a listener, and a compensation spectrum determination unit configured to determine a frequency compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum.

[0013] Further aspects emerge from the dependent claims, the following description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments will now be described by way of example and with reference to the accompanying drawings, in which: Fig. Figure 1 shows a diagram schematically illustrating the relationship between a source frequency response, 1 / f noise and a corresponding perceived frequency response; Fig. Figure 2 shows a diagram schematically illustrating the relationship between 1 / f noise, a compensated frequency response and a perceived frequency response; Fig. 3 schematically shows an embodiment of a device for determining a compensation spectrum; Fig. 4 schematically shows another embodiment of an apparatus for determining a compensation spectrum; Fig. 5 schematically describes an example of subtracting the audio reference spectrum from the audio noise spectrum; Fig. 6 schematically shows an embodiment of an apparatus for generating a compensated audio signal based on a source signal file and a compensation spectrum; Fig. 7 shows an embodiment of a method for generating a compensated audio signal; and Fig. 8 shows another embodiment of a method for determining a compensated audio signal. DETAILED DESCRIPTION OF EMBODIMENTS

[0015] Before a detailed description of the embodiments is given with reference to the drawings, some general explanations are given.

[0016] Methods are disclosed herein that include determining an audio noise spectrum representing external audio noise, determining an audio reference spectrum representing audio content to be perceived by a listener, and determining a compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum.

[0017] The disclosed method can be used to determine the external noise spectrum at a listener's ear and dynamically adjust the frequency response of an electronic device, such as a music player, so that the listener is able to hear all frequencies of the desired musical material in an optimized manner.

[0018] The method can be applied, for example, in an electronic device such as a music player, in particular in a portable music player such as a mobile phone or a portable audio player. However, the disclosure is not limited to such use. The concept disclosed in this specification can also be used, for example, in connection with radios in vehicles or in other situations where noise disrupts a listener's perception of the audio content.

[0019] External audio noise can be, for example, the sound of a moving train when music is being played in a train compartment. External audio noise can also be the sound of an engine inside a vehicle, or something similar.

[0020] An audio noise spectrum can, for example, be a frequency spectrum obtained from detected external audio noise. An audio noise spectrum can, for example, be obtained using a fast Fourier transform (FFT) of a detected audio noise signal.

[0021] For example, an audio noise spectrum can be represented by a set of frequencies and corresponding phases. An audio noise spectrum can also be represented by a power spectrum. A power spectrum can be represented, for example, by amplitudes or squared amplitudes.

[0022] The audio noise signal can be captured, for example, using a microphone. The microphone can be connected to an audio playback device or it can be a microphone built into the audio playback device. In specific embodiments, a microphone is connected to an electronic device to optimize the capture of external audio noise.

[0023] Audio content perceived by a listener can be any type of audio signal generated by an electronic device, such as an audio playback device, to be heard by a listener. The listener can, for example, use headphones to hear the audio content. The audio content can, for example, be a piece of music, an audio stream of a radio transmission, or the like.

[0024] An audio reference spectrum can be obtained using a fast Fourier transform (FFT) and can be represented, for example, by frequencies, phases, amplitudes, or squared amplitudes. In particular, the audio reference spectrum can be represented as a power spectrum comprising amplitudes or squared amplitudes.

[0025] The audio reference spectrum and the audio noise spectrum can, for example, be represented by a sound pressure level (SPL) spectrum of sound impacting the ears of a listener. The sound pressure level (SPL), or acoustic sound pressure, is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. A commonly used reference sound pressure in the ear is the threshold of human perception, which is 20 µPa.

[0026] An audio noise spectrum together with an audio reference spectrum can be used to determine a compensation spectrum.

[0027] A compensation spectrum can be used to control an equalizer to adjust the balance between frequency components of an audio signal heard by a listener.

[0028] A compensation spectrum can be represented, for example, by frequencies, phases, amplitudes, and / or squared amplitudes. A compensation spectrum can, in particular, be a power spectrum comprising amplitudes or squared amplitudes.

[0029] A compensation spectrum can comprise any number of data values ​​(e.g., amplitudes, squared amplitudes, or the like). For example, a compensation spectrum can comprise only a few values ​​representing specific ranges within the frequency spectrum, such as low frequencies (bass), mid frequencies, and high frequencies. However, a compensation spectrum can also comprise a large number of data values, with each frequency range represented by many data values. In other words, a compensation spectrum can be chosen as fine or coarse as desired, depending on the specific needs and / or design.

[0030] For example, a compensation spectrum can be used to adjust the balance between frequency components of a music signal reproduced by an electronic device such as an audio player or a mobile phone.

[0031] Determining the audio noise spectrum may include calculating a noise sound pressure level spectrum of external noise based on a detected audio noise signal. In particular, determining an audio noise spectrum may include calculating a noise sound pressure level spectrum at the listener's ears. For example, a transfer function may be used to calculate a noise sound pressure level spectrum at the listener's ears, where the transfer function describes the attenuation of external noise on its way through a headphone.

[0032] Determining an audio reference spectrum may include calculating a reference sound pressure level spectrum based on a detected audio reference signal and based on a sensitivity function. A sensitivity function may, for example, describe the sensitivity of a headphone used by a listener to hear audio content. A sensitivity function relates electrical power supplied to a headphone to a corresponding sound pressure level received by the headphone based on the electrical power. The sensitivity of a headphone may, for example, be defined as the sound pressure level (dB lin.) at 1 mW nominal power at 1 kHz.

[0033] An audio reference signal can be obtained by measuring a voltage signal at an audio output amplifier of an electronic device. The voltage signal can thus correspond to a voltage signal transmitted from an audio output amplifier of an audio playback device to a pair of headphones.

[0034] In alternative embodiments, the audio reference signal is obtained by detecting an audio source signal generated by an audio renderer. In this case, the audio reference signal can be obtained, for example, by amplifying an audio source signal generated by an audio renderer according to the gain control of a listener, and then converting this audio source signal using a Fast Fourier Transform (FFT) to obtain an audio reference spectrum.

[0035] Determining a compensation spectrum may include subtracting the audio reference spectrum from the audio noise spectrum.

[0036] A compensation spectrum can be obtained, for example, by subtracting a power spectrum of the audio noise from a power spectrum of the audio reference.

[0037] The compensation spectrum can be subtracted from a target frequency response, resulting in amplification or cutoff of corresponding frequencies.

[0038] The compensation spectrum can be limited to avoid exceeding a certain gain or to cut off certain frequencies, thus minimizing the energy required for compensation and ensuring that the reproduction capabilities of a headphone driver are not exceeded.

[0039] The method may further comprise integrating the compensation spectrum over a specific time period. This may prevent abrupt changes in the frequency compensation that could disrupt the listener's perception of the audio content. The integration may, for example, be performed on a time scale of a few seconds, such as three seconds, five seconds, or even more seconds. In particular, the integration may result in an averaging of the compensation spectrum over a specific time period.

[0040] The method may further comprise determining a compensated audio signal based on the compensation spectrum and the audio source signal. This may allow the frequency response to be dynamically adjusted so that a listener can always perceive all music frequencies in a well-balanced manner and no degradation occurs, particularly in the bass frequency range.

[0041] Determining a compensated audio signal based on the compensation spectrum and based on an audio source signal may include balancing the audio source signal according to the compensation spectrum. For example, determining a compensated audio signal based on the compensation spectrum and based on an audio source signal may be implemented by an equalizer that balances an audio source signal based on compensation values ​​obtained from a compensation spectrum.

[0042] Determining the compensation spectrum can also be based on a target spectrum. The target spectrum can represent user preferences, such as a setting that boosts the bass frequencies relative to the mid and high frequencies.

[0043] However, the target spectrum can also be a user option. If a user does not actively provide user preferences, the target spectrum can be set to flat, meaning no modification of the compensation spectrum is performed.

[0044] The method may further include limiting the compensation spectrum. This limiting can be implemented, for example, using a limiting block and can be used to prevent a certain gain from being exceeded or to cut off certain frequencies, thus minimizing the energy required for compensation and ensuring that the reproduction capabilities of a headphone driver are not exceeded.

[0045] The disclosed methods can preserve the full sound perception of all frequencies of a musical performance, even in the presence of external masking by ambient noise. The methods can dynamically adjust to varying levels of external noise, allowing all spectral components to be heard at all times.

[0046] The embodiments also disclose an electronic device comprising a noise spectrum determination unit configured to determine an audio noise spectrum representing external audio noise, a reference spectrum determination unit configured to determine an audio reference spectrum representing audio content to be perceived by a listener, and a compensation spectrum determination unit configured to determine a frequency compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum.

[0047] The electronic device may be, for example, an audio playback device or a mobile phone, a car radio or another sound reproduction system.

[0048] The noise spectrum determination unit may include a microphone for detecting external sounds (or external noise).

[0049] The electronic device may further comprise an equalizer configured to balance an audio signal based on the compensation spectrum.

[0050] Embodiments will now be described with reference to the accompanying drawings.

[0051] Fig. Figure 1 shows a diagram that schematically describes the relationship between a source frequency response, 1 / f noise, and the perceived frequency response. The diagram shows frequency values ​​on the abscissa and corresponding amplitude levels on the ordinate. The dotted line represents a source frequency response of an audio content perceived by a listener. The dashed line indicates the frequency response of an external noise signal. The noise signal has a 1 / f characteristic, which means that the noise is large at low frequencies and the noise becomes smaller with increasing frequencies. As shown in the diagram of the Fig. As can be seen in Figure 1, the perceived frequency response is attenuated in areas where the 1 / f noise is large. The solid line describes the frequency response as perceived by the listener.

[0052] If a 1 / f frequency spectral distribution of the ambient noise is considered, as in Fig. 1 is the case, the low frequencies in particular are perceived less intensely. In the case of other noise distributions, other frequency ranges could also be affected.

[0053] Fig. Figure 2 shows a diagram schematically describing the relationship between a compensated frequency response, 1 / f noise, and a perceived frequency response. Again, the dashed line indicates a frequency response of an external noise signal. The dotted line represents a source frequency response of the audio content that has been compensated using a compensation spectrum. The compensated source frequency response essentially corresponds to the source frequency response in Fig. 1. However, equalization altered the balance of the frequency components of the source frequency response to compensate for attenuation by 1 / f noise. This means that in the low frequency ranges, balancing the source frequency response increases the amplitude of the source frequency response, so that a corresponding compensated frequency response is larger than the original source frequency response. The compensated frequency response, if affected by the 1 / f noise signal, is attenuated, but the compensation spectrum is chosen such that the attenuated compensated frequency response results in a perceived frequency response (solid line in Fig. 2) which is largely similar to the original source frequency response (see Fig. 1).

[0054] Here, in particular, the compensated source frequency response has increased the frequencies in the bass range, so that the attenuation by 1 / f noise does not lead to a deterioration of the listening experience.

[0055] Fig. 3 schematically shows an embodiment of a device for determining a compensation spectrum based on an audio noise spectrum and based on an audio reference spectrum.

[0056] A microphone 1 captures external audio noise. The audio noise signal is amplified by an amplifier 3. The amplified noise signal is passed through a low-pass filter 5, which passes signals with frequencies below a certain threshold frequency and attenuates signals with frequencies greater than the threshold frequency. The low-pass filtered signal is fed to an analog-to-digital (A / D) converter 7, which converts the captured audio signal into a digital signal. The digital signal is subjected to a fast Fourier transform (FFT) 9 to generate a frequency spectrum. A transfer function 11 is then applied to the resulting frequency spectrum. The transfer function 11 simulates the attenuation of the external noise as it propagates to the listener's ears. The resulting audio noise spectrum represents the sound pressure level perceived at the listener's ears.The resulting audio noise spectrum is passed through a logarithmic unit 13, which logarithmizes the audio noise spectrum.

[0057] The result of this calculation is an audio noise spectrum, in this case a sound pressure level (SPL) spectrum, which represents external audio noise as perceived by a listener. The resulting audio noise spectrum can be further processed together with an audio reference spectrum, as described in more detail below.

[0058] An audio reference spectrum is obtained as follows.

[0059] A voltage measurement is taken at the output amplifier of an electronic device. The measured voltage signal represents the signal that the output amplifier delivers to the loudspeaker 15 (here, a pair of headphones). The measured voltage signal is amplified in an amplifier 17, passed through a low-pass filter 19, and converted into digital data by an analog-to-digital (A / D) converter 21. The digital data is fed to a fast Fourier transform 23, and the resulting frequency spectrum is processed in a sensitivity function 25, which converts the electrical voltage measurement into a sound level. The sensitivity function 25 makes it possible to estimate the sound pressure level (SPL) that acts on the listener's ears when the electrical signal measured at the output amplifier is fed to the headphones 15.The resulting sound pressure level spectrum is logarithmized in the logarithm unit 27 to obtain an audio reference spectrum.

[0060] The audio reference spectrum thus obtained can be further processed together with an audio noise spectrum obtained at the logarithm unit 13.

[0061] In this embodiment, the audio reference spectrum obtained at the logarithm unit 27 is subtracted from the audio noise spectrum obtained at the logarithm unit 13.

[0062] During subtraction, the sound pressure level (SPL) values ​​of the audio noise spectrum and the audio reference spectrum are subtracted from each other.

[0063] Furthermore, as explained below with reference to Fig. 5, subtracting the audio reference spectrum from the audio noise spectrum may include limiting the compensation spectrum to a frequency range defined by a maximum frequency.

[0064] The resulting difference spectrum can be used as a compensation spectrum.

[0065] After subtraction, the difference spectrum is fed to an integrator 29, which integrates the difference spectrum over a certain period of time.

[0066] The resulting reference spectrum is then modified based on a target spectrum 31. This target spectrum 31 represents user preferences. The modification can, for example, consist of subtracting or adding the target spectrum from the difference spectrum.

[0067] The resulting modified difference spectrum is then passed to a limiter 33, which limits the difference spectrum in such a way that a certain gain is not exceeded or certain frequencies are cut off.

[0068] The resulting limited difference signal, which is based on the audio noise spectrum obtained from microphone 1 and the audio reference spectrum obtained from the voltage measurement at the output amplifier feeding the loudspeaker 15, can then be used as a compensation spectrum in further processing.

[0069] Fig. Figure 4 shows an alternative embodiment of a method for determining a compensation spectrum based on an audio noise spectrum and based on an audio reference spectrum. The determination of an audio noise spectrum is similar to the previously described embodiment with respect to Fig. 3. A microphone 1 detects external audio noise. The detected audio noise signal is amplified in an amplifier 3 and passed through a low-pass filter 5, then digitized in an analog-to-digital (A / D) converter 7, passed through a fast Fourier transform 9, processed by a transfer function 11, and logarithmized in a logarithm unit 13 to obtain an audio noise spectrum.

[0070] An audio reference spectrum is obtained by rendering an audio content with an audio renderer 37, passing the resulting audio signal through a user-controlled gain control 39, passing the resulting signal through a fast Fourier transform 41, and logarithmizing the resulting signal with the logarithm unit 43.

[0071] The resulting audio frequency spectrum is further processed together with the audio noise spectrum as follows.

[0072] The audio reference spectrum obtained from microphone 1 is subtracted from the audio noise signal obtained from audio renderer 37. The resulting difference signal is integrated in integrator 29 and then modified by a target spectrum 31. The resulting difference spectrum is finally passed through a limiter 33 to obtain the compensation spectrum 35.

[0073] Fig. Figure 5 schematically shows an example of subtracting the audio reference spectrum from the audio noise spectrum. In this embodiment, subtracting the audio reference spectrum from the audio noise spectrum involves limiting the compensation spectrum to a frequency range defined by a maximum frequency.

[0074] First, amplitudes of an audio reference spectrum F ref (dotted line) of amplitudes of an audio noise spectrum F noise (dashed line) subtracted to find differences F noise- F ref Then a maximum function F diff = max(F noise - F ref , 0) on the differences F noise - F ref applied so that negative values ​​of the differences are set to zero. As a result, the compensation is limited to a frequency range defined by a maximum frequency f max is limited, where f max corresponds to the frequency value at which the audio noise spectrum and the audio reference spectrum have equal values.

[0075] Furthermore, in this embodiment, below a minimum frequency f min The compensation is continuously reduced to zero to avoid overloading an audio system. This limitation can be implemented, for example, in the limiter 33 of the Fig. 3, for example, after subtracting the audio reference spectrum from the audio noise spectrum and after integrating the difference spectrum. Alternatively, the limiting can also take place directly during the subtraction or immediately after the subtraction.

[0076] The final compensation spectrum obtained in this way is Fig. 5 shown as a solid line.

[0077] It should be noted that in order to make subtraction easy to understand, in the schematic diagram of the Fig. 5 the audio reference spectrum is simplified as a flat spectrum. In reality, the shape of the audio reference spectrum can, of course, be more complex. For example, the shape of the audio reference spectrum can resemble the shape of the Fig. 1 shown source frequency spectrum.

[0078] In the description above, an embodiment was described in which a compensation spectrum is obtained by subtracting an audio reference spectrum from an audio noise spectrum. Other ways of obtaining the compensation spectrum based on an audio reference spectrum and based on an audio noise spectrum are also conceivable. For example, in an alternative embodiment, a set of possible reference spectra and noise spectra are pre-stored in a lookup table along with corresponding predefined compensation spectra. In this case, a compensation spectrum can be obtained by searching the lookup table for an entry that is close to a measured audio reference spectrum and a measured audio noise spectrum, and the predefined compensation spectrum for the found entry can then be selected as the compensation spectrum to be applied.

[0079] Fig. 6 schematically shows an apparatus for determining a compensated audio signal based on a compensation spectrum and based on an audio source signal.

[0080] An audio source signal 37 (e.g., the output of a media player) is fed to an equalizer 45. The equalizer 45 is configured to adjust the balance between frequency components of the audio source signal 37 based on the compensation spectrum 35. The equalizer outputs a compensated audio signal. The compensated audio signal is passed through a user-controlled gain control 47 and is then output to a loudspeaker 49, here a pair of headphones used by a listener of the audio source signal. This loudspeaker may, for example, be the same loudspeaker as loudspeaker 15 in Fig. 3, where the audio reference signal is received. This means that the compensated audio signal can itself act as an audio reference signal, and the compensation will automatically stabilize itself.

[0081] As described above, the equalizer 45 is configured to balance the frequency components of the audio source signal 37 based on the compensation spectrum 35. If, for example, the compensation spectrum has large values ​​in the lower frequency range, the equalizer 45 amplifies the low-frequency components of the audio source signal 37 accordingly. Conversely, if the compensation spectrum has small values ​​in a particular frequency range, the equalizer 45 does not modify the corresponding frequency components of the audio source signal 37. In some embodiments, equalizer settings are obtained directly from a compensation spectrum. In other embodiments, a lookup table is used that links predefined compensation spectra to corresponding equalizer settings.

[0082] Fig. 7 shows an embodiment of a method for determining a compensated audio signal based on a compensation spectrum and an audio source signal. At 701, an audio noise signal is captured using a microphone. At 703, a voltage signal at an audio output amplifier of an electronic device is measured to obtain an audio reference signal. At 705, a noise sound pressure level spectrum of the external noise is calculated based on the captured audio noise signal. At 707, a reference sound level spectrum is calculated based on the audio reference signal and based on a sensitivity function. At 709, the audio noise spectrum and the audio reference spectrum are subtracted to obtain a compensation spectrum. At 711, the compensation spectrum is integrated over a specific time period. At 713, the compensation spectrum is limited.Finally, at 715, a compensated audio signal is determined based on the compensation spectrum and based on the audio source signal.

[0083] Fig. 8 shows another embodiment of a method for determining a compensated audio signal based on a compensation spectrum and based on an audio source signal. At 801, an audio noise signal is captured using a microphone. At 803, an audio source signal generated by an audio renderer is captured to obtain an audio reference signal. At 805, a noise sound pressure level spectrum of external noise is calculated based on a captured audio noise signal. At 807, a reference sound pressure level spectrum is calculated based on the audio reference signal and based on a sensitivity function. At 809, the audio noise spectrum and the audio reference spectrum are subtracted. At 811, the compensation spectrum is integrated over a certain period of time. At 813, the compensation spectrum is limited. Finally, at 815, a compensated audio signal is determined based on the compensation spectrum and based on the audio source signal.

[0084] The methods described herein are also implemented, in some embodiments, as a computer program that, when executed on a computer and / or processor, causes a computer and / or processor to perform the method. In some embodiments, a non-transitory computer-readable storage medium is also provided that stores a computer program product that, when executed on a processor, such as the processor described above, causes the methods described herein to be performed.

[0085] It should be noted that the embodiments show methods in an exemplary order of method steps. However, the specific order of the method steps is for exemplary purposes only and should not be considered binding. For example, the order of 701 and 703 or the order of 705, 707 in the embodiment of Fig. 7. The order of 709 and 711 in the embodiment of the Fig. 7. Furthermore, the order of 711 and 713 in the embodiment of the Fig. 7. The same applies to corresponding steps in the embodiment of the Fig. 8. Further changes in the sequence of process steps may be apparent to the person skilled in the art.

[0086] It should also be noted that the division of the device of the Fig. 3 or Fig.4 in units is merely exemplary, and the present disclosure is not limited to a specific division of functions into specific units. For example, the Fast Fourier Transform (FFT) 9 and the transfer function 11 may also be implemented by a correspondingly programmed processor, a field-programmed gate array (FPGA), or the like.

[0087] All units and entities described in this specification and claimed in the appended claims may, unless otherwise stated, be implemented by integrated circuit logic, for example on a chip, and functionality provided by such units and entities may, unless otherwise stated, be implemented by software.

[0088] Insofar as the embodiments described above are implemented at least partially using a software-controlled data processing device, it should be understood that a computer program providing such software control and also a transmission, storage or other medium through which such a computer program is provided are also to be regarded as an aspect of the present disclosure.

[0089] It should also be noted that the present technology can also be designed as described below. (1) Procedure comprising: Determining an audio noise spectrum that represents external audio noise, Determining an audio reference spectrum representing audio content perceived by a listener, and Determining a compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum. (2) The method according to (1), wherein determining the audio noise spectrum comprises calculating a noise sound pressure level spectrum of external noise based on a detected audio noise signal. (3) Method according to (2), in which the audio noise signal is detected with a microphone. (4) The method according to any one of (1) to (3), wherein determining an audio reference spectrum comprises calculating a reference sound pressure level spectrum based on a detected audio reference signal and based on a sensitivity function. (5) The method according to any one of (1) to (4), wherein the audio reference spectrum is obtained by measuring a voltage signal at an audio output amplifier of an electronic device. (6) The method according to any one of (1) to (4), wherein the audio reference signal is obtained by detecting an audio source signal generated by an audio renderer. (7) The method of any one of (1) to (6), wherein determining the compensation spectrum comprises subtracting the audio reference spectrum from the audio noise spectrum. (8) The method of any one of (1) to (7), further comprising integrating the compensation spectrum over a certain period of time. (9) The method of any one of (1) to (8), further comprising determining a compensated audio signal based on the compensation spectrum and based on the audio source signal. (10) The method of (9), wherein determining a compensated audio signal based on the compensation spectrum and based on the audio source signal comprises balancing the audio source signal according to the compensation spectrum. (11) The method according to any one of (1) to (10), wherein determining the compensation spectrum is further based on a target spectrum. (12) The method according to any one of (1) to (11), further comprising limiting the compensation spectrum. (13) Electronic device comprising: a noise spectrum determination unit configured to determine an audio noise spectrum representing external audio noise, a reference spectrum determination unit configured to determine an audio reference spectrum representing an audio content to be perceived by a listener, and a compensation spectrum determining unit configured to determine an audio compensation spectrum based on the audio noise spectrum and based on the audio reference spectrum. (14) The electronic device according to (13), wherein the noise spectrum determining unit comprises a microphone for detecting external audio noise. (15) The electronic device according to (13) or (14), wherein the reference spectrum determining unit is configured to measure a voltage signal at an audio output amplifier of the electronic device. (16) The electronic device according to any one of (13) to (15), further comprising an equalizer configured to balance an audio source signal based on the compensation spectrum. (17) A computer program comprising instructions which, when executed on a processor of an electronic device, cause the electronic device to: determines an audio noise spectrum that represents external audio noise, determines an audio reference spectrum that represents audio content perceived by a listener, and a compensation spectrum is determined based on the audio noise spectrum and based on the audio reference spectrum. (18) A computer program comprising instructions, the instructions, when executed on a processor of an electronic device, causing the method of any one of (1) to (11) to be carried out.

Claims

[1] Procedure comprising: Determining an audio noise spectrum (F noise ), which represents external audio noise, Determining an audio reference spectrum (F ref ), which represents audio content perceived by a listener, Determining a compensation spectrum (35) based on the audio noise spectrum (F noise ) and based on the audio reference spectrum (F ref ), in which the determination of the compensation spectrum (35) comprises subtracting the audio reference spectrum (F ref ) from the audio noise spectrum (F noise ), and Balancing an audio source signal (37) according to the compensation spectrum (35). [2] Method according to claim 1, wherein determining the audio noise spectrum (F noise ) calculating a noise sound pressure level spectrum of external noise based on a detected audio noise signal. [3] Method according to claim 2, wherein the audio noise signal is detected with a microphone (1). [4] Method according to one of claims 1 to 3, wherein the determination of an audio reference spectrum (F ref ) comprises calculating a reference sound pressure level spectrum based on a detected audio reference signal and based on a sensitivity function (25). [5] Method according to one of claims 1 to 4, wherein the audio reference spectrum (F ref ) is obtained by measuring a voltage signal at an audio output amplifier of an electronic device. [6] Method according to one of claims 1 to 4, wherein the audio reference signal (F ref ) is obtained by detecting the audio source signal (37) generated by an audio renderer. [7] Method according to one of claims 1 to 6, further comprising integrating the compensation spectrum (35) over a certain period of time. [8] Method according to one of claims 1 to 7, wherein the determination of the compensation spectrum (35) is further based on a target spectrum (31). [9] Method according to one of claims 1 to 8, further comprising limiting the compensation spectrum (35). [10] Electronic device comprising: a noise spectrum determination unit configured to determine an audio noise spectrum (F noise ) that represents external audio noise, a reference spectrum determination unit configured to determine an audio reference spectrum (F ref ) that represents audio content perceived by a listener, a compensation spectrum determination unit configured to determine a compensation spectrum (35) based on the audio noise spectrum (F noise ) and based on the audio reference spectrum (F ref), in which the determination of the compensation spectrum (35) comprises subtracting the audio reference spectrum (F ref ) from the audio noise spectrum (F noise ), and an equalizer (45) configured to balance an audio source signal (37) based on the compensation spectrum (35). [11] The electronic device according to claim 10, wherein the noise spectrum determining unit comprises a microphone (1) for detecting external audio noise. [12] The electronic device according to claim 10 or 11, wherein the reference spectrum determining unit is configured to measure a voltage signal at an audio output amplifier of the electronic device. [13] A computer program comprising instructions, the instructions, when executed on a processor of an electronic device, causing the electronic device to: an audio noise spectrum (F noise) which represents external audio noise, an audio reference spectrum (F ref ) that represents the audio content perceived by a listener, a compensation spectrum (35) based on the audio noise spectrum (F noise ) and based on the audio reference spectrum (F ref ), in which the determination of the compensation spectrum (35) comprises subtracting the audio reference spectrum (F ref ) from the audio noise spectrum (F noise ), and an audio source signal (37) is balanced based on the compensation spectrum (35).

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