Patent Publication Number: US-11653137-B2

Title: Method at an electronic device involving a hearing device

Description:
RELATED APPLICATION DATA 
     This application claims priority to, and the benefit of, Danish Patent Application No. PA 202070493 filed on Jul. 17, 2020. The entire disclosure of the above application is expressly incorporated by reference herein. 
     FIELD AND BACKGROUND 
     A “hearing device” may be of a type with or without compensation for a user&#39;s hearing loss. 
     In some aspects the hearing device is a hearing instrument, e.g. denoted a hearing aid, including compensation for a user&#39;s hearing loss. The hearing instrument may be fitted in accordance with a so-called open fitting or a so-called closed fitting as it is known in the art. 
     In some aspects the hearing device is an ear-phone configured as a headset and for listening to audio signals, e.g. music, and including one or more microphones for receiving sounds from the surroundings, preferably, the user&#39;s speech. 
     The hearing device may include spatial filtering techniques such as beamforming and/or filtering in a time-frequency domain. The hearing device may also include active noise-cancellation. 
     Generally, a user may wear one hearing device in one ear or one in each ear. A hearing device is configured for full or partial insertion in an ear canal and includes an acoustic input transducer, e.g. a microphone or an array of microphones, typically capturing acoustic waves from the surroundings of the user and coupled to an acoustic output transducer, e.g. a miniature loudspeaker, arranged close to and/or facing a the user&#39;s eardrum, when the hearing device is inserted in the ear canal. 
     It has been observed that, since the hearing device is configured for full or partial insertion in an ear canal, and since the ear canal is thus fully or partially blocked or occupied, also acoustically, the wearer perceives sound from the surroundings as not sounding natural. This is sometimes explained by the passive dampening of acoustic waves propagation in the ear canal by the hearing device or rather its housing and any members thereof. 
     It is observed that the advent of hearing devices with a so-called hear-though mode, wherein the passive dampening is deliberately compensated for by amplification, is not sufficient. A hear-though mode lets the user hear acoustic sounds from the surroundings despite of, e.g. significant, passive dampening in the ear canal while wearing the hearing devices. A hear-through mode can normally be engaged or disengaged, e.g. by the user and works, when engaged, while listening to, e.g. music, from an audio source or while using the hearing device as headset for telephone or conference calls and also when worn without being engaged in a call or without listening to an audio source. 
     In practice, this has led to a lack of acoustic fidelity and inconveniences for users. 
     Also, “headphones”, “a pair of headphones” or a headphone are known in the art and include one or two ear-cups each accommodating an acoustic output transducer, e.g. a small loudspeaker, for reproducing an electric audio signal as an acoustic signal. The ear-cups sometimes include a cushion or other type of soft member, which makes wearing headphones more comfortable. The ear-cup rests on the wearer&#39;s ear or at the head while covering the ear. Typically, headphones include a headband for keeping the headphone(s) in place on the wearer&#39;s head. Headphones may be of a closed type, wherein only a small amount of sound leaks out from the space formed between the ear cup and the wearer&#39;s ear and/or head. Headphones may alternatively be of an open type, wherein a larger amount of sound leaks out from the ear-cup. 
     Throughout this application, the terms ‘band’ and ‘frequency band’ are used interchangeably. 
     SUMMARY 
     It is observed that conventional hearing devices, configured for being at least partially inserted in a user&#39;s one or both ear(s) degrades at least the fidelity of acoustic sounds from the surroundings, in particular when a hear-through mode is engaged. 
     The claimed method obtains frequency band specific gain values for a so-called flat insertion gain filter. The flat insertion gain filter improves fidelity in the reproduction of sounds from the surrounds at the user&#39;s ear drum while wearing the hearing device at least partially inserted in the user&#39;s one or both ear(s). In some aspects of the method, it may be assumed that the user intends to wear a hearing device in one ear and to not wear a hearing device in the other ear. In some aspects of the method, it may be assumed that the user has a symmetric hearing at the left ear and the right ear. 
     There is provided a method comprising: at an electronic device with, one or more communication elements; 
     enabling first communication, via the one or more communication elements, to a pair of headphones including a first acoustic output transducer and a second acoustic output transducer; 
     enabling second communication, via the one or more communication elements, to a first hearing device; wherein the first hearing device is configured for insertion in an ear canal and includes an acoustic input transducer coupled to an acoustic output transducer via a first gain stage; 
     for each period of time of multiple periods of time; wherein each period of time is associated with a band of multiple bands: 
     communicating a band-limited portion of a first audio test signal via a second gain stage and via the first acoustic output transducer to a user&#39;s first eardrum and communicating a band-limited portion of a second audio test signal via the second acoustic output transducer to a user&#39;s other eardrum; 
     controlling a gain value of the first gain stage and/or a gain value of the second gain stage and, in response to the user&#39;s first input, determining a first gain value specifically for the band, based on the gain value of the first gain stage and/or the gain value of the second gain stage; wherein the first gain value is associated with the user&#39;s perception of equal loudness at both ears; and 
     storing the first gain value for the band. 
     The method is performed by the electronic device and involves a user&#39;s first input. The method may be implemented in an application program, e.g. known as an app, running on the electronic device. The method is based on the user wearing the headphones and wearing the first hearing device in the one ear canal, while no hearing device is inserted in the other ear canal. The method enables obtaining one or more first gain values for a first flat insertion gain filter. The first flat insertion gain filter enables improved fidelity e.g. in connection with a hear-through mode of the first hearing device. Rather than obtaining values enabling compensation for the user&#39;s potential hearing loss caused by impaired auditory sensitivity in the physiological auditory system, the method obtains values enabling compensation for the hearing device fully or partially occupying the ear canal and thereby altering the user&#39;s hearing compared to not wearing a hearing device fully or partially occupying the ear canal. 
     The first gain value is based on the gain value of the first gain stage and/or the gain value of the second gain stage. In some aspects, the gain value of the second gain stage is fixed, the gain value of the first gain stage is controlled, and the first gain value is determined to be equal to the gain value of the first gain stage. The gain value of the first gain stage is thereby a controlled gain value. In other aspects, the gain value of the second gain stage is controlled, the gain value of the first gain stage is fixed, and the first gain value is determined to be equal to the gain value of the second gain stage. The gain value of the second gain stage is thereby a controlled gain value. The first gain value is based on the controlled gain value. In some aspects, both the gain value of the first gain stage and the gain value of the second gain stage are controlled. The second gain stage may be accommodated at the headphones and/or at the electronic device e.g. in software. 
     The method may be performed as a session or part of a session involving the user. The session may be a second session, which is followed by a third session. In the third session, the method is based on the user wearing headphones and wearing a second hearing device in the other ear canal, while no hearing device is inserted in the one ear canal. The method, in the third session, enables obtaining one or more second gain values for a second flat insertion gain filter. The second flat insertion gain filter enables improved fidelity e.g. in connection with a hear-through mode of the second hearing device. The first hearing device may be configured for a left ear, while the second hearing device is configured for a right ear, or vice versa. 
     The second session and the third session may be preceded by a first session, wherein the method is based on the user wearing the headphones and not wearing a hearing device in either the one ear or in the other ear. The first session may obtain gain values for compensating for a user&#39;s different hearing at the one ear and the other ear. However, it is possible to forgo using the first session e.g. based on a user&#39;s rejection of the first session. 
     At least while in a hear-through mode, the first and/or second hearing device is configured to communicate an acoustic signal captured by the acoustic input transducer to the acoustic output transducer via the flat insertion gain filter. This communication is in addition to acoustic waves propagating from the surroundings to the eardrum via the ear canal, which is partially occupied by the hearing device or rather a housing and any members, e.g. flexible or non-flexible, thereof. In particular, in accordance with the method, the wearer of the hearing device may perceive the acoustic sounds from the surroundings, sounding more natural. The acoustic sounds from the surroundings may sound more natural both in terms of amplitude and in terms of absence of or at least reduced colorization of the sounds. 
     In some examples the first audio test signal and the second audio test signal are monaural. When reference is made to a test signal, it is a reference to both signals, monaurally, or as different signals. The test signal is distributed across an audible spectrum or a portion thereof. The test signal may be distributed between a lower frequency of about 20 Hz to an upper frequency in the range about 6 kHz to 20 kHz, e.g. at 8 kHz or 12 kHz. In some examples, the first audio test signal and the second audio test signal are different, and not monaural, but have a substantially equal power spectrum. 
     The test signal is communicated at different periods of times and at multiple bands. The multiple bands may include bands at bass, midrange and treble. Finer or coarser selection of bands may be used. In some aspects, bands are selected in accordance with a non-linear scale e.g. the Bark scale. The bands may be defined by a range of frequencies and/or by a centre frequency. Bands may be enumerated and identified accordingly. 
     As an example, the multiple bands may include three bands e.g. enumerated bass, midrange and treble, respectively. A bass portion of the audio test signal is communicated to the user&#39;s ear drums during a first period of time and the first gain value is stored for the bass band e.g. as a first element of an array. A midrange portion of the audio test signal is communicated to the user&#39;s ear drums during a second period of time and the first gain value is stored for the midrange band e.g. as a second element of the array. A treble portion of the audio test signal is communicated to the user&#39;s ear drums during a third period of time and the first gain value is stored for the treble band e.g. as a third element of the array. The first gain values for the different bands may be communicated to the hearing device for the flat insertion gain filter e.g. element by element or in another way. For example, the first gain value is determined, based on the user&#39;s first input and the user&#39;s perception of equal loudness at both ears to be 0 dB for the bass band, +3 dB for the midrange and +6 dB for the treble. In another example, the first gain values are [+3 dB, 0 dB, 3 dB, 9 dB] for respective bands e.g. with a centre frequency of [60 Hz, 300 Hz, 1000 Hz; 8kHz]. In some examples, the first gain value is determined for one band, e.g. a treble band, whereas one or more bands at lower frequencies has/have a fixed gain. The first gain values may be obtained by controlling the gain value of the first gain stage and/or a gain value of the second gain stage. These examples also apply, mutatis mutandis, for a second gain value described further below. 
     Preferably, the periods of time do not overlap. In some aspects the bands do not overlap or overlap partially. In some aspects, one or more bands fully overlap(s) another band. The duration of the periods may be selected automatically, or the duration of the periods may be based on a user&#39;s input e.g. by a user giving input to proceed with the session. 
     The first audio test signal and the second audio test signal should enable the user to perceive whether loudness is stronger at one ear (e.g. balance is to the left) or the other ear (e.g. balance is to the right) or whether loudness is equal at both ears (e.g. balance is at the centre). The audio test signal should have at least periods with fairly static loudness, rather than a dynamic loudness to enable the user time to perceive whether loudness is stronger at one ear or the other ear or whether loudness is equal at both ears. The audio test signal may have fade-in periods and fade-out periods. The test signal may be a noise signal, e.g. band limited white or coloured noise. The test signal may be recorded or composed to include natural sounds e.g. sounds resembling water streams or waves or winds in trees and the like. Natural sounds may be perceived to be more pleasant than noise signals. The test signal may include a single tone or multiple tones. The test signal may be composed from any combinations of the above. 
     In some aspects, the band-limited portion of the first audio test signal and the band-limited portion of the second audio test signal is communicated at the same time or at different, e.g. immediately subsequent, periods of time. Listening to the test signal at both ears at the same time may be perceived as enabling a more easy judgement of balance or, alternatively, listening, to the test signal at one ear at a time may be perceived as enabling a more easy judgement of balance. In some examples, the method enables the user to select either listening at both ears at the same time or listening at both ears, one ear at a time. In some aspects, the method includes a first sub-session enabling listening at both ears at the same time and a second sub-session enabling listening at both ears, one ear at a time. 
     The first gain stage may be included in a flat insertion gain filter. In some aspects, the flat insertion gain filter is accommodated in the hearing device. This enables the more natural reproduction of acoustic sounds without requiring a connection to the electronic device while the hearing device is in a hear-through mode. In other aspects, the flat insertion gain filter is accommodated in the electronic device, wherein the communication from the acoustic input transducer to the acoustic output transducer takes place, e.g. by wireless communication, via the electronic device. 
     In some aspects, the enabling of the first communication and/or the enabling of the second communication includes establishing a wireless communication from the electronic device. The wireless communication may be in accordance with a Bluetooth protocol or another wireless protocol e.g. a proprietary wireless protocol. The first communication, to the pair of headphones includes e.g. streaming of the test signal from the electronic device to the headphones or establishing a streaming connection from a signal source to the headphones. The signal source may be at a remote server or at the headphones. 
     The second communication may include information for accessing an application programmable interface of the hearing device. The application programmable interface may enable setting and/or reading of a gain value for the first gain stage or a flat insertion gain filter. The gain value of the first gain stage may be set and/or read via a so-called gain handle. 
     In some aspects, the band-limited portions of the test signal are band-limited to match band filters of the flat insertion gain filter(s). Thus, whereas the test signal is synthesized or sampled, the flat insertion gain filters are supposed to filter any signal captured by the acoustic input transducer of the hearing device. A perfect match between the band-limited portions of the test signal and the flat insertion gain filters is not necessary, but a certain correspondence is needed to reduce colorization of the sounds in a hear-through mode. 
     The flat insertion gain filter can be used in one or both of the first hearing device and the second hearing device. The flat insertion gain filter may be coupled between the acoustic input transducer coupled to an acoustic output transducer. A flat insertion gain filter can be provided based on the one or more first gain values. The first gain stage may be a gain stage of a flat insertion gain filter. 
     In some aspects, the electronic device comprises a display and one more or more input elements. The display may be a light source, such as one or more LEDs or a graphic display comprising a matrix of pixels. The input elements may comprise physical buttons and/or touch-sensitive elements arranged to sense touch on the display. In some aspects, the electronic device is a personal computer. In some examples the electronic device is a smart-phone or a smart-watch or a tablet computer. In some examples, the electronic device is an electronic auxiliary device configured to control a hearing device. In some aspects, the communication elements include one or more wireless communication elements e.g. for Bluetooth communication. 
     In some aspects, the band-limited portions of the audio test signal are separated in time. The band-limited portions of the audio test signal may be separated by a time period determined by a user&#39;s response. 
     In some embodiments the electronic device and/or the first hearing device is/are operatively coupled to a second hearing device; and wherein the second hearing device is configured for insertion in an ear canal and includes an acoustic input transducer coupled to an acoustic output transducer via a third gain stage; comprising: 
     for each period of time of multiple periods of time; wherein each period of time is associated with a band of multiple bands: 
     communicating a band-limited portion of a third audio test signal via a fourth gain stage and via the second acoustic output transducer to a user&#39;s second eardrum and communicating a band-limited portion of a fourth audio test signal via the second acoustic output transducer to the user&#39;s second eardrum; 
     controlling a gain value of the third gain stage and/or a gain value of the fourth gain stage and, in response to the user&#39;s second input, determining a second gain value for the band, based on the gain value of the third gain stage and/or the gain value of the fourth gain stage; wherein the second gain value is associated with the user&#39;s perception of equal loudness at both ears; 
     storing the second gain value for the band 
     This part of the method may be performed as a part of a third session following the second session. Both the second session and the third session involve the user. 
     In the third session, the method is also based on the user wearing headphones but wearing a second hearing device in the other ear canal, while no hearing device is inserted in the one ear canal. Thus, the user should remove the first hearing device from the one ear and insert the second hearing device in the other ear. The user may do this between the second session and the third session. The user may need to (re-)move the headphones while inserting and removing the hearing devices. 
     The method, in the third session, enables obtaining one or more second gain values for a second flat insertion gain filter. The second flat insertion gain filter enables improved fidelity e.g. in connection with a hear-through mode of the second hearing device. The first hearing device may be configured for a left ear, while the second hearing device is configured for a right ear, or vice versa. 
     The user wearing both hearing devices may, as a result, perceive that sounds from the surroundings sound more natural or at least will less colorization of the sound. 
     In some aspects, the first hearing device is operatively coupled to a second hearing device. Thereby, the electronic device can communicate gain values for the second hearing device via the first hearing device. The first hearing device and the second hearing device may preferably be coupled via a wireless connection. 
     In some aspects, the method comprises enabling a third communication, via the one or more communication elements, to the second hearing device. 
     In some embodiments the method comprises: 
     for each period of time of multiple periods of time; wherein each period of time is associated with a band of multiple bands: 
     (1) controlling a gain value of the second gain stage and/or a gain value of the first gain stage and, in response to the user&#39;s third input, determining a third gain value specifically for the band, based on the gain value of the first gain stage and/or the gain value of the second gain stage; wherein the third gain value is associated with the user&#39;s perception of equal loudness at both ears; 
     (2) storing the third gain value for the band; and 
     obtaining the first gain value and/or the second gain value based on communicating the first audio signal and/or the second audio signal via equalization; wherein the equalization is configured to change gain at a band in accordance with a gain value based on the third gain value for the band. 
     This part of the method may be performed as a part of at least a first session preceding the second session and preceding the third session, if any. The first session involves the user and generates third gain values based on which the second session and the third session can be performed. In particular, the first session enables compensation for a difference in hearing at the user&#39;s left ear and right ear. This in turn improves the gain values for the flat insertion gain filter(s), especially when the user has different hearing on one ear compared to the other ear. In particular, but not limited thereto, when performing the method at the first session with a user who has different hearing on one ear compared to the other ear, the first flat insertion gain filter(s) enable improved fidelity e.g. in connection with a hear-through mode of the first hearing device. 
     In some aspects, the first session is based on controlling gain in a left side and keeping the gain in the right side fixed or controlling gain in the right side and keeping the gain in the left side fixed. 
     In the first session, the method is also based on the user wearing headphones but without wearing a hearing device inserted in any of the ear canals. 
     The third gain values may also, or alternatively, be used for playback of music or speech signals through the headphones. The third gain values may then be stored in the electronic device. 
     In some embodiments the method comprises: 
     communicating a first message at a time before the user&#39;s first input, wherein the first message indicates that the headphones are to be worn while: the first hearing device is to be inserted in the user&#39;s first ear; and the second hearing device is to be kept out of the other ear; and 
     receiving the user&#39;s first input at a time following a first time of the first message. 
     Thereby the user is given instructions of how to interact with the electronic device for performing the technical task of obtaining gain values for a flat insertion gain filter. The first time of the first message may be a time at which the first message commences or at a time when the first message is complete. 
     In some aspects, the first message is communicated and/or the user&#39;s first input is received during the second session. The first message may be communicated by displaying an image and/or video and/or one or more graphical elements and/or text elements. The first message may additionally or alternatively be communicated by outputting. e.g. via the headphones and/or a loudspeaker integrated in the electronic device, spoken passages of text. 
     In some aspects, the method involves displaying a first user interface screen with one or more affordances on a display of the electronic device for receiving the user&#39;s input, e.g. the user&#39;s first input, via a touch-sensitive display. In some aspects the method involves displaying a slider affordance for the user to adjust the gain values or a balance. In some aspects the method involves displaying a button affordance for receiving a user&#39;s first input. In some aspects, the user&#39;s first input is received at the slider affordance e.g. in response to the lapse of a timer, which is started when the slider is moved a first time. 
     Additionally, or alternatively, the electronic device may receive the user&#39;s input via input elements, e.g. via touch-sensitive input elements, of the headphones. 
     The user&#39;s input may be a ‘tap’ gesture and/or a ‘slide’ gesture and/or a ‘swipe’ gesture. In some aspects, the user&#39;s input is a spoken audio input, which is received via a microphone of the electronic device or via a microphone of the headphones or a microphone of the hearing device. 
     In some embodiments the method comprises: 
     communicating a second message at a time after the user&#39;s first input and before the user&#39;s second input, wherein the second message indicates that the headphones are to be worn while the first hearing device is to be kept out of the user&#39;s first ear; and the second hearing device is to be inserted in the user&#39;s other ear; and 
     receiving the user&#39;s second input at a time following a first time of the second message. 
     In some aspects, the second message is communicated and/or the user&#39;s second input is received during the third session. 
     The user&#39;s second input is preferably received as described in connection with the user&#39;s first input. In particular, in some aspects, the method involves displaying a second user interface screen with one or more affordances on a display of the electronic device for receiving the user&#39;s input, e.g. the user&#39;s first input, via a touch-sensitive display. 
     In some embodiments the method comprises: 
     communicating a third message, wherein the third message indicates that the headphones are to be worn while the first hearing device and the second hearing device are to be kept out of the user&#39;s ears; and 
     receiving the user&#39;s third input at a time following a first time of the third message. 
     In some aspects, the third message is communicated and/or the user&#39;s third input is received during the first session. 
     The user&#39;s third input is preferably received as described in connection with the user&#39;s first input and/or the user&#39;s second input. In particular, in some aspects, the method involves displaying a third user interface screen with one or more affordances on a display of the electronic device for receiving the user&#39;s input, e.g. the user&#39;s third input, via a touch-sensitive display. 
     Preferably, the third message is communicated to the user and user&#39;s third input is received before the first message is communicated to the user. 
     In some embodiments the first hearing device comprises a first set of gain filters coupled between the acoustic input transducer and the acoustic output transducer; wherein the first set of gain filters is configured to change gain at a band in accordance with a gain value based on the first gain value, G L , for the band; and/or the second hearing device comprises a second set of gain filters coupled between the acoustic input transducer and the acoustic output transducer; wherein the second set of gain filters is configured to change gain at a band in accordance with a gain value based on the second gain value specifically for the band. 
     Thereby one or both of the first hearing device and the second hearing device is configured with filters enabling improved fidelity e.g. in connection with a hear-through mode of the hearing devices. The filters may be used for frequency-gain equalization and/or for flat insertion gain filters enabling improved fidelity. 
     In some embodiments the method comprises: 
     communicating, to the first hearing device, a first set of gain values, each based on the first gain value for the band; and/or 
     communicating, to the second hearing device, a second set of gain values, each based on the second gain value for the band. 
     Thereby one or both of the first hearing device and the second hearing device is configured with a flat insertion gain filter enabling improved fidelity e.g. in connection with a hear-through mode of the hearing devices. The flat insertion gain filters are based on the gain values obtained using the method at the electronic device, in interaction with the user giving input, for associating gain values with the user&#39;s perception of equal loudness at both ears. 
     A hear-through mode may be enabled at the first hearing device and/or the second hearing device at times when the hearing device is playing music or communicating a voice signal. The hear-through mode may be enabled at any time when the hearing device is active. 
     In some embodiments, at each period of time of the multiple periods of time, any of the audio signals is/are band-limited to the band associated with the period of time. 
     Preferably, the periods of time do not overlap. In some aspects the bands do not overlap or overlap partially. In some aspects, one or more bands fully overlap(s) another band. The duration of the periods may be selected automatically, or the duration of the periods may be based on a user&#39;s input e.g. by a user giving input to proceed with the session. 
     As an example, the multiple bands may include three bands e.g. enumerated bass, midrange and treble, respectively. A bass portion of the audio test signal is communicated to the user&#39;s ear drums during a first period of time and the first gain value is stored for the bass band e.g. as a first element of an array. A midrange portion of the audio test signal is communicated to the user&#39;s ear drums during a second period of time and the first gain value is stored for the midrange band e.g. as a second element of the array. A treble portion of the audio test signal is communicated to the user&#39;s ear drums during a third period of time and the first gain value is stored for the treble band e.g. as a third element of the array. 
     As an example, one or more of the audio test signals is limited to bands at lower frequencies during first periods of time and limited to bands at higher frequencies during subsequent periods of time e.g. by shifting the band-limited portion upwards or downwards in frequency during the course of subsequent periods of time. The user may then perceive the audio test signal as gradually increasing or gradually decreasing in frequency. The band-limited portions may also be in a randomized order. 
     The audio test signal(s) may be synthesized by band-specific generators or be generated as signal distributed across multiple bands, wherein the audio test signal is subsequently filtered by a band-pass filter for the respective band. 
     The multiple periods of time may have a predetermined maximum duration; wherein the method stores a first gain value and/or a second gain value based on a default gain value which may be a current gain value of a gain stage. 
     In some embodiments the method comprises: displaying, on the display, a first affordance for receiving a user&#39;s balance input and for the controlling of the gain value of the first gain stage and/or the gain value of the second gain stage; and in response to receiving the user&#39;s balance input, adjusting the gain value of the first gain stage and/or the gain value of the second gain stage. 
     In this way the gain is adjusted at one side via the balance input. The gain of the other side may be held fixed at least while receiving the user&#39;s input is enabled. 
     The first affordance may be a slider affordance or a rotatable-wheel affordance. The first affordance may comprise buttons for stepwise tapping higher or lower values. The affordance provides values for controlling the gain values e.g. based on a scale conversion. In some aspects, the first gain value is determined based on a value obtained from the first affordance. 
     In some embodiments the method comprises: communicating the first audio signal at different gain levels at different periods of time; and displaying, on the display, a second affordance for receiving a user&#39;s accept of perceived equal loudness; and in response to receiving the user&#39;s accept, storing the first gain value and/or the second gain value and/or the third gain value. 
     Thereby, the user is not required to move a slider or other control input. Rather the user can tap the second affordance at a first location to accept that loudness is perceived to be equal at both ears or, by tapping at a second location, to reject that loudness is perceived to be equal at both ears. After communicating at least a portion of the first audio signal at different balance settings at different periods of time, the users accept may be given. 
     Same or substantially same portions of the audio test signal may be communicated once during a session or in a repeated or randomized manner during a session. 
     The audio test signal is communicated at different balance settings and at different bands at different periods of time. Inputs received via the second affordance are registered at a point in time associated with a balance setting at the point in time and a band of the band-limited audio test signal at the point in time. 
     In some embodiments the method comprises: 
     determining whether to deploy the first gain value and/or the second gain value, and in accordance with a determination to deploy the first gain value and/or the second gain value: 
     deploying a set of the first gain value at or for a set of gain filters at the first hearing device; and/or 
     deploying a set of the second gain value at or for a set of gain filters at the second hearing device. 
     The determination, whether to deploy the first gain value, may be based on a determination that a user fulfilment criterion is satisfied. The user fulfilment criterion may include that a user&#39;s input is received for all or a predetermined set or number of the multiple bands and/or that a user&#39;s input is received for all or a predetermined set or number of the multiple periods of time. Thus, it may be determined that the user has fully completed or partly completed one or more sessions and that the gain values obtained can be deployed at or for the hearing device to improve fidelity e.g. in a hear-through mode. 
     In some embodiments the first gain value and/or the second gain value for the bands are confined to a predefined increment and/or decrement and/or to predefined gain levels. 
     Thereby, a trade-off between fidelity and time required to complete one or more of the sessions is provided. The predefined increment and/or decrement and/or to predefined gain levels may enable the user to select a gain level more quickly, which is perceived as providing equal loudness at both ears. 
     Examples of predefined increments and/or decrements may be +2 dB and −2 dB or +3 dB and −3 dB. Other finer or coarser increments and/or decrements may be used. Examples of predefined gain levels may be [0 dB, +3 dB, +6 dB, +9 dB]. In some examples a more progressive scale may be used. The gain levels may be limited to predefined maximum values and/or predefined minimum values. 
     In some embodiments the user&#39;s first input, for the user&#39;s first ear, is received concurrently with the user wearing the first hearing device in the first ear and not wearing a second hearing device in the second ear. 
     In some embodiments, the first hearing device and the second hearing device are included in a pair of hearing devices and are configured for wearing in or at a user&#39;s first ear and in or at a user&#39;s second ear, respectively. 
     In some embodiments the user&#39;s second input, for the user&#39;s second ear, is received concurrently with the user wearing the second hearing device in the second ear and not wearing the first hearing device in the first ear. 
     In some embodiments the user&#39;s third input, is received concurrently with the user not wearing any of the first and second hearing devices inserted in any of the user&#39;s ears. Thereby it is possible to correct the balance of the user&#39;s (asymmetric) hearing between his/hers two ears. 
     In some embodiments the method comprises: 
     controlling the gain value of the first gain stage ( 122 ) and/or the gain value of the second gain stage ( 137 ) in response to the user&#39;s first input during a second session; and 
     controlling the gain value of the third gain stage ( 127 ) and/or a gain value of the fourth gain stage ( 138 ) in response to the user&#39;s second input during a third session; 
     wherein the second session and the third session do not overlap in time. 
     Thus, the user gives his/her input for one ear at the time, during different sessions. Since one of the ears (one of the ear canals) is not occupied by a hearing device, the ‘free’ ear, can serve as a reference for the user assessing when equal loudness is perceived (in response to his input). 
     In some embodiments the method comprises: determining the third gain value in response to the user&#39;s third input during a first session; wherein the first session precedes the second session and the third session. 
     Thereby it is possible to obtain compensation (balance) of the user&#39;s (asymmetric) hearing between his/hers ears before determining the first gain value and the second gain value. 
     In some embodiments the method comprises forgoing performing a fitting procedure to determine compensation for the user&#39;s possible hearing loss. Thus, the method does not obtain values enabling compensation for the user&#39;s potential hearing loss. 
     There is also provided an electronic device, comprising: 
     one or more communication elements; 
     a display; 
     one or more input elements; 
     at least one processor coupled to the one or more communication elements; the display; the one or more input elements; and 
     a memory storing at least one program, wherein the at least one program is configured to be executed by the one or more processors, the at least one program including instructions for performing the method. 
     In some aspects, the electronic device is a smart-phone or a smart-watch, a tablet computer, or another type of personal computer. 
     In some aspects, the electronic device is an electronic auxiliary device configured to control a hearing device. In some aspects, the communication elements include one or more wireless communication elements e.g. for Bluetooth communication. 
     In some aspects, the electronic device is included in a pair of headphones. 
     There is also provided a computer readable storage medium storing at least one program, the at least one program comprising instructions, which, when executed by the at least one processor of an electronic device with one or more communication elements; a display; one or more input elements; and at least one processor, enables the electronic device to perform the method. 
     The computer readable storage medium may be a non-transitory computer-readable medium e.g. in the form of RAM or ROM memory. The computer-readable storage medium may be accommodated at the electronic device or at a server computer. 
     The term ‘processor’ may include a combination of one or more hardware elements. In this respect, a processor may be configured to run a software program or software components thereof. One or more of the hardware elements may be programmable or non-programmable. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       A more detailed description follows below with reference to the drawing, in which: 
         FIG.  1   a    shows an electronic device;  FIG.  1   b    shows hardware elements of the electronic device;  FIG.  1   c    shows a block diagram of a pair of hearing devices; and  FIG.  1   d    shows a block diagram of a pair of headphones; 
         FIGS.  2   a  and  2   b    show examples of user interfaces for a first session; 
         FIG.  3    shows a pair of headphones in position for the first session; 
         FIG.  4    shows a flowchart for the first session; 
         FIGS.  5   a ,  5   b  and  5   c    show examples of user interfaces for a second session; 
         FIG.  6    shows a pair of headphones and a hearing device in position for the second session; 
         FIG.  7    shows a flowchart for the second session; 
         FIGS.  8   a ,  8   b  and  8   c    show examples of user interfaces for a third session; 
         FIG.  9    shows a pair of headphones and a hearing device in position for the third session; 
         FIG.  10    shows a flowchart for the third session; 
         FIG.  11    shows a time-frequency chart for a test signal; 
         FIG.  12    shows a bank of gain filters for deploying flat insertion gain filters; 
         FIG.  13    shows a general flowchart for an embodiment of the method; and 
         FIG.  14    shows embodiments of a pair of headphones and a pair of hearing devices. 
     
    
    
     DETAILED DESCRIPTION 
     Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described. 
     Assume that the hearing device has a microphone at the entrance of the ear canal and a miniature speaker (receiver) inside the ear canal pointing towards the eardrum. Furthermore, assume that the hearing device does not block the ear canal completely such that some sound can pass around the device without being amplified. 
     Flat insertion gain refers to an equalized or substantially flat amplitude transfer function. 
     Flat insertion gain G flat  is obtained if the following expression is satisfied: 
     
       
         
           
             
               
                 
                   
                     
                       
                         H 
                         closed 
                       
                       ⁢ 
                       
                         G 
                         flat 
                       
                     
                     + 
                     
                       H 
                       dir 
                     
                   
                   = 
                   
                     
                       
                         H 
                         
                           o 
                           ⁢ 
                           p 
                           ⁢ 
                           e 
                           ⁢ 
                           n 
                         
                       
                       → 
                       
                         G 
                         flat 
                       
                     
                     = 
                     
                       
                         
                           H 
                           
                             o 
                             ⁢ 
                             p 
                             ⁢ 
                             e 
                             ⁢ 
                             n 
                           
                         
                         - 
                         
                           H 
                           dir 
                         
                       
                       
                         H 
                         closed 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
         
         Wherein: 
         H closed  is the transfer function from a far field speaker to the microphone multiplied by the transfer function from the receiver to the ear drum of the ear canal blocked by the device. 
         G flat  is the frequency dependent gain in the device. 
         H open  is the transfer function from the far field speaker to the eardrum of the unblocked ear. 
         H dir  is the transfer function from the far field speaker to the eardrum of the blocked ear where the sound has not been amplified by the device (the direct path around the device or through a vent). 
       
    
     Note that equation 1 does not depend on the direction to the speaker as long as the microphone is placed at the entrance to the ear canal and the bandwidth of the sound is below about 12 kHz. 
     Assume now that we want to find a simple way of measuring the gain G flat  in the listening devices on both ears such that flat insertion gain is obtained. The proposed method is based on the following sessions: 
     First Session 
     The user places a pair of headphones on his head (they do not need to be flat or calibrated in any way). The headphones are playing monaural, band limited noise with centre frequency f 0  (alternatively this could also be a pure tone signal with centre frequency f 0 ) and the user can adjust the gain G hp   Right  in the right ear headphone to match the perceived loudness of his left ear. 
     The user will now adjust the gain G hp   Right  in the right ear headphone such that the perceived loudness on both his ears are equal. That is: 
                       H     o   ⁢   p   ⁢   e   ⁢   n       L   ⁢   e   ⁢   f   ⁢   t       ⁢     A   left       =       H     o   ⁢   p   ⁢   e   ⁢   n       R   ⁢   i   ⁢   g   ⁢   h   ⁢   t       ⁢     G     h   ⁢   p       R   ⁢   i   ⁢   g   ⁢   h   ⁢   t       ⁢     A     r   ⁢   i   ⁢   g   ⁢   h   ⁢   t                 (   2   )               
where A left  and A right  are the users hearing loss on each ear (note it can be asymmetric). The centre frequency f 0  of the bandlimited noise is thereafter changed to a new frequency and the procedure is repeated until all frequencies of interest are covered.
 
     Second Session 
     Now the user places the left ear device in his left ear and put on the headphones. Again the headphones are playing monaural, band limited noise with centre frequency f 0  where the gain in the right ear headphone is set to G hp   Right  and the user adjusts the gain G L  in the left ear device such that the perceived loudness on both ears are equal. That is: 
     
       
         
           
             
               
                 
                   
                     
                       ( 
                       
                         
                           
                             H 
                             closed 
                             Left 
                           
                           ⁢ 
                           
                             G 
                             L 
                           
                         
                         + 
                         
                           H 
                           dir 
                           Left 
                         
                       
                       ) 
                     
                     ⁢ 
                     
                       A 
                       Left 
                     
                   
                   = 
                   
                     
                       H 
                       
                         o 
                         ⁢ 
                         p 
                         ⁢ 
                         e 
                         ⁢ 
                         n 
                       
                       
                         R 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                     ⁢ 
                     
                       G 
                       
                         h 
                         ⁢ 
                         p 
                       
                       
                         R 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                     ⁢ 
                     
                       A 
                       
                         r 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     Again, the procedure is repeated for all frequencies of interest. 
     Third Session 
     Finally, the user removes the left ear device and puts the right ear device in his right ear. Again, the headphones are playing monaural, band limited noise with center frequency f 0  and the gain in the right ear headphone is set to G hp   Right . The user adjust the gain G R  in the right ear device such that the perceived loudness on both ears are equal. That is: 
     
       
         
           
             
               
                 
                   
                     
                       H 
                       
                         o 
                         ⁢ 
                         p 
                         ⁢ 
                         e 
                         ⁢ 
                         n 
                       
                       Left 
                     
                     ⁢ 
                     
                       A 
                       left 
                     
                   
                   = 
                   
                     
                       
                         G 
                         
                           h 
                           ⁢ 
                           p 
                         
                         
                           R 
                           ⁢ 
                           i 
                           ⁢ 
                           g 
                           ⁢ 
                           h 
                           ⁢ 
                           t 
                         
                       
                       ⁡ 
                       
                         ( 
                         
                           
                             
                               H 
                               closed 
                               
                                 R 
                                 ⁢ 
                                 i 
                                 ⁢ 
                                 g 
                                 ⁢ 
                                 h 
                                 ⁢ 
                                 t 
                               
                             
                             ⁢ 
                             
                               G 
                               R 
                             
                           
                           + 
                           
                             H 
                             dir 
                             
                               R 
                               ⁢ 
                               i 
                               ⁢ 
                               g 
                               ⁢ 
                               h 
                               ⁢ 
                               t 
                             
                           
                         
                         ) 
                       
                     
                     ⁢ 
                     
                       A 
                       
                         r 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     Again, the procedure is repeated for all frequencies of interest. 
     Deriving Flat Insertion Gain 
     The right hand side of equation 2 and 3 are equal so we have: 
                       (         H   closed     L   ⁢   e   ⁢   f   ⁢   t       ⁢     G   L       +     H   dir     L   ⁢   e   ⁢   f   ⁢   t         )     ⁢     A     L   ⁢   e   ⁢   f   ⁢   t         =       H     o   ⁢   p   ⁢   e   ⁢   n       L   ⁢   e   ⁢   f   ⁢   t       ⁢     A   left               (   5   )               
which gives:
 
                     G   L     =         H     o   ⁢   p   ⁢   e   ⁢   n       L   ⁢   e   ⁢   f   ⁢   t       -     H   dir     L   ⁢   e   ⁢   f   ⁢   t           H   closed     L   ⁢   e   ⁢   f   ⁢   t                 (   6   )               
and from equation 1 it follows that
 
                     G   L     =     G     f   ⁢   l   ⁢   a   ⁢   t       L   ⁢   e   ⁢   f   ⁢   t               (   7   )               
which is the flat insertion gain for the left ear.
 
     The flat insertion gain filter for the right ear is found by observing that the left hand side of equation 2 and equation 4 are equal. This gives: 
     
       
         
           
             
               
                 
                   
                     
                       H 
                       
                         o 
                         ⁢ 
                         p 
                         ⁢ 
                         e 
                         ⁢ 
                         n 
                       
                       
                         R 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                     ⁢ 
                     
                       G 
                       
                         h 
                         ⁢ 
                         p 
                       
                       
                         R 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                     ⁢ 
                     
                       A 
                       
                         r 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                   
                   = 
                   
                     
                       
                         G 
                         
                           h 
                           ⁢ 
                           p 
                         
                         
                           R 
                           ⁢ 
                           i 
                           ⁢ 
                           g 
                           ⁢ 
                           h 
                           ⁢ 
                           t 
                         
                       
                       ⁡ 
                       
                         ( 
                         
                           
                             
                               H 
                               closed 
                               
                                 R 
                                 ⁢ 
                                 i 
                                 ⁢ 
                                 g 
                                 ⁢ 
                                 h 
                                 ⁢ 
                                 t 
                               
                             
                             ⁢ 
                             
                               G 
                               R 
                             
                           
                           + 
                           
                             H 
                             dir 
                             
                               R 
                               ⁢ 
                               i 
                               ⁢ 
                               g 
                               ⁢ 
                               h 
                               ⁢ 
                               t 
                             
                           
                         
                         ) 
                       
                     
                     ⁢ 
                     
                       A 
                       
                         r 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                   
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
             
               
                 
                   
                     G 
                     R 
                   
                   = 
                   
                     
                       
                         H 
                         
                           o 
                           ⁢ 
                           p 
                           ⁢ 
                           e 
                           ⁢ 
                           n 
                         
                         
                           R 
                           ⁢ 
                           i 
                           ⁢ 
                           g 
                           ⁢ 
                           h 
                           ⁢ 
                           t 
                         
                       
                       - 
                       
                         H 
                         dir 
                         
                           R 
                           ⁢ 
                           i 
                           ⁢ 
                           g 
                           ⁢ 
                           h 
                           ⁢ 
                           t 
                         
                       
                     
                     
                       H 
                       closed 
                       
                         R 
                         ⁢ 
                         i 
                         ⁢ 
                         g 
                         ⁢ 
                         h 
                         ⁢ 
                         t 
                       
                     
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
     Substituting this expression into equation 1 directly gives: 
                     G   R     =     G   flat     R   ⁢   i   ⁢   g   ⁢   h   ⁢   t               (   10   )               
which is the flat insertion gain filter for the right ear.
 
     We have now shown that the gain settings G L  and G R  we measured are equal to the flat insertion gain settings we need to use in the devices to get flat insertion gain. 
     The centre frequencies of the bandlimited noise played over the headphones should cover the range in which flat insertion gain is desired. A natural choice is to use the frequencies defined by the Bark scale and let the corresponding noise signals match the width of the auditory filters. 
       FIG.  1   a    shows an electronic device. The electronic device  100  includes a touch-sensitive display  101 , physical input buttons  102 ,  103  and  104 , a camera lens  106  for a built-in camera (not shown) and a loudspeaker opening  105 . The electronic device  100  displays a set of icons and/or affordances designated ‘M’, ‘12’, ‘C’, ‘H’, ‘C’ and ‘P’. An affordance, as known in the art of graphical user interfaces, has a graphical icon and properties that help a user understand that they can interact with it, and the type of interaction that may be involved. For instance, the affordance ‘C’ may be tapped to activate an application, e.g. an app, that performs the method described herein. 
       FIG.  1   b    shows hardware elements of the electronic device;  FIG.  1   c    shows a block diagram of a pair of hearing devices; and  FIG.  1   d    shows a block diagram of a pair of headphones. The hardware elements comprise a processor  110  that may include a combination of one or more hardware elements. In this respect, the processor may be configured to run one or more a software programs or software components thereof including the application that can be activated via the affordance ‘C’. The processor  110  is coupled to an audio circuit  111 , a radio frequency circuit  112 , including one or more antennas  115 , a display  113 , which may be display  101 , a touch input circuit  114  and a memory  115 . 
       FIG.  1   c    shows a block diagram of a pair of hearing devices. The hearing devices  120  and  121  may be configured as hearing instruments to compensate for a hearing loss or be configured as a headset or ear-phones without compensating for a hearing loss. The hearing device  120  may be configured for insertion in an e.g. left ear canal and the hearing device  121  may be configured for insertion in an e.g. right ear canal. The hearing devices may have same or similar circuits, but differently shaped housings to fit in a left ear canal or a right ear canal. 
     The hearing devices  120 ;  121  comprises an acoustic input transducer  117 ;  128 , e.g. a microphone, arranged in the hearing device at an opening of the ear canal. An acoustic output transducer  123 ;  126 , e.g. a miniature loudspeaker, is arranged in the hearing device towards the eardrum. A gain stage  122 ;  127  is controlled via a controller  124 ;  129  that can communicate wirelessly with the electronic device  100 . In some aspects, the gain stage  122 ;  127  is a part of a filter or equalizer e.g. a part of the flat insertion gain filter at least when the hearing device  120 ;  121  is engaged in a hear-through mode. 
     In some aspects, the gain stage  122 ;  127  is a gain stage without a filter, which is used during one or several of the sessions described herein. Since the first test signal is band-limited, the gain stage  122 ;  127  may be a gain stage without a filter. 
       FIG.  1   d    shows a block diagram of a pair of headphones. The pair of headphones  130  includes a first ear-cup  133  and a second ear-cup  134  each accommodating an acoustic output transducer  135 :  136 , e.g. a small loudspeaker. The pair of headphones includes a controller  131  which can communicate, e.g. wirelessly via antenna  132 , with the electronic device  100 . The pair of headphones also include a gain stage  137  for the acoustic output transducer  135  and a gain stage  138  for the acoustic output transducer  136 . The gain stages  137  and  138  sets the loudness level communicated towards the user&#39;s ears. The gains of the gain stages  137 ;  138  can be controlled by the controller  131 , which may include setting and getting respective gain values. 
     In some aspects, the gain stages  137 ;  138  are additionally or alternatively included in an application running on the electronic device or in circuitry of the electronic device  100 . 
       FIGS.  2   a  and  2   b    show examples of user interfaces for a first session. The electronic device  100  displays a user interface screen displaying a message  201  at a first time and a user interface screen displaying a message  202  at a second point in time. The user may give input to proceed from one user interface screen to another e.g. by a swipe gesture. The user interface screen also shows an affordance  207 , in the form of a slider, and an affordance  203 . The user may give his input  204  e.g. to move the slider. It is possible to get values from the slider for determining the third gain value. When the slider is at a rightmost position, it can correspond to a low value of the third gain value, whereas when the slider is at a leftmost position it can correspond to a high value of the first gain value. 
     The affordance  203  includes buttons  206  and  208  for advancing from one band-limited portion of the audio test signal to another band-limited portion of the audio test signal and/or for advancing from one session to another e.g. when a session has been completed e.g. when the user has given input for all band-limited portions of the audio test signal. The user may give his input  205  e.g. to advance to another band-limited portion of the audio test signal and/or to another session as mentioned above. 
     The messages, in any of the sessions, may be replaced by or accompanied by spoken audio instructions. The spoken audio instructions may be a human speaker&#39;s recorded voice or voice synthetically generated from text elements. The spoken audio instructions may be played back by a loudspeaker of the electronic device or played back by the pair of headphones. 
       FIG.  3    shows a pair of headphones in position for the first session. The pair of headphones  130  is worn on the user&#39;s head and rests on or covers the user&#39;s ears, in particular the user&#39;s ear canals  301  and  302 . The user&#39;s ear drums are designated by reference numerals  303  and  304 . 
       FIG.  4    shows a flowchart for the first session. At the first session, the method  400  starts at step  401  e.g. in response to a user tapping, on a touch-sensitive display of the electronic device, an affordance for activating an application. At step  402  a user interface screen, UI-1, e.g. including messages  201  and  202 . Thereby the user is given instructions about what to do during the first session. At step  403  the audio test signal is communicated to the user via the headphones one band, B(n), at a time. A band-limited portion of the audio test signal is thereby communicated to the user. The method later reverts to step  403  to communicate another band-limited portion of the audio test signal to the user. The band-limited portions may be enumerated n=[1 . . . N] e.g. n=[1,2,3,4,5]. 
     At step  404 , a user&#39;s first balance input is received. The input may be given via a slider, e.g. slider  207 , or another variable input e.g. a rotatable wheel. The gain values of the first gain stage and/or the second gain stage may be set in accordance with a value from the slider. Once the user is satisfied that the loudness is perceived as being equal at both ears, the user may give a first accept input e.g. via button  206  whereby the method proceeds to step  405  wherein the user&#39;s first accept input is received. The method then proceeds to step  406  to store the third gain value for band B(n). The method may then revert to step  403 , via step  407  (N), and continue the method as described above for a next band-limited portion. 
     When all band-limited portions have been communicated to the user and the user has given the corresponding inputs, third gain values have been determined for all of the multiple bands. Then, the method determines at step  407  to proceed to a next session (Y). 
     Thereby, it is possible to obtain the first gain value and/or the second gain value (for multiple bands, e.g. one band at a time) based on communicating the first audio signal and/or the second audio signal via equalization; wherein the equalization is configured to change gain at a band in accordance with a gain value based on the third gain value for the band. 
     It is possible to forgo or skip the first session or to dispense with performing the method for the first session, e.g. if it is assumed that the user&#39;s hearing (loss) is symmetric between the left ear and the right ear. 
       FIGS.  5   a ,  5   b  and  5   c    show examples of user interfaces for a second session. The electronic device  100  displays a user interface screen displaying a message  501  at a first time and a user interface screen displaying a message  502  at a second point in time and a message  509  at a third time. The user may give input to proceed from one user interface screen to another e.g. by a swipe gesture. The user interface screen also shows an affordance  507 , in the form of a slider, and an affordance  503 . The user may give his input  504  e.g. to move the slider. It is possible to get values from the slider for determining the second gain value. When the slider is at a rightmost position, it can correspond to a low value of the second gain value, whereas when the slider is at a leftmost position it can correspond to a high value of the second gain value. 
     The affordance  503  includes buttons  506  and  208  for advancing from one band-limited portion of the audio test signal to another band-limited portion of the audio test signal and/or for advancing from one session to another e.g. when a session has been completed e.g. when the user has given input for all band-limited portions of the audio test signal. The user may give his input  505  e.g. to advance to another band-limited portion of the audio test signal and/or to another to another session as mentioned above. 
       FIG.  6    shows a pair of headphones and a hearing device in position for the second session. The pair of headphones  130  is worn on the user&#39;s head and rests on or covers the user&#39;s ears, in particular the user&#39;s ear canals  301  and  302 . The user&#39;s ear drums are designated by reference numerals  303  and  304 . 
     Also shown is that the hearing device  120  is inserted in the left ear canal  301 . Acoustic sounds from the surroundings passes the hearing device  120  as shown by arrow  601  which extends towards the eardrum  303  from an outer periphery of the ear canal  301 . 
       FIG.  7    shows a flowchart for the second session. At the second session, which may or may not follow the first session, the method  700  starts at step  701  e.g. in response to a user tapping, on a touch-sensitive display of the electronic device, an affordance for activating an application or in response to having completed the first session. At step  702  a user interface screen, UI-2, e.g. including messages  501 ,  502  and  509 . Thereby the user is given instructions about what to do during the second session. At step  703  the audio test signal is communicated to the user via the headphones one band, B(n), at a time. The method later reverts to step  703  to communicate another band-limited portion of the audio test signal to the user. The band-limited portions may be enumerated n=[1 . . . N] e.g. n=[1,2,3,4,5]. 
     At step  704 , the user&#39;s second balance input is received. The input may be given via a slider, e.g. slider  507 , or another variable input e.g. a rotatable wheel. The gain values of the first gain stage and/or the second gain stage may be set in accordance with a value from the slider. Once the user is satisfied that the loudness is perceived as being equal at both ears, the user may give a second accept input e.g. via button  506  whereby the method proceeds to step  705 , where the user&#39;s second accept input is received. The method then proceeds to step  706  to store the first gain value for band B(n). The method may then revert to step  703 , via step  707  (N), and continue the method as described above for a next band-limited portion. 
     When all band-limited portions have been communicated to the user and the user has given the corresponding inputs, first gain values have been determined for all of the multiple bands. Then, the method determines at step  707  to proceed to another session or to communicate to the user that the session or sessions is/are completed (Y). 
     Thereby, it is possible to obtain the first gain value and/or the second gain value (for multiple bands, e.g. one band at a time) e.g. based on third gain values obtained during the first session—or based on fixed third gain values obtained in another way than via the first session. 
       FIGS.  8   a ,  8   b  and  8   c    show examples of user interfaces for a third session. The electronic device  100  displays a user interface screen displaying a message  801  at a first time and a user interface screen displaying a message  802  at a second point in time and a message  809  at a third time. The user may give input to proceed from one user interface screen to another e.g. by a swipe gesture. The user interface screen also shows an affordance  807 , in the form of a slider, and an affordance  803 . The user may give his input  804  e.g. to move the slider. It is possible to get values from the slider for determining the second gain value. When the slider is at a rightmost position, it can correspond to a low value of the second gain value, whereas when the slider is at a leftmost position it can correspond to a high value of the second gain value. 
     The affordance  803  includes buttons  806  and  808  for advancing from one band-limited portion of the audio test signal to another band-limited portion of the audio test signal and/or for advancing from one session to another e.g. when a session has been completed e.g. when the user has given input for all band-limited portions of the audio test signal. The user may give his input  805  e.g. to advance as mentioned above. 
       FIG.  9    shows a pair of headphones and a hearing device in position for the third session. The pair of headphones  130  is worn on the user&#39;s head and rests on or covers the user&#39;s ears, in particular the user&#39;s ear canals  301  and  302 . The user&#39;s ear drums are designated by reference numerals  303  and  304 . 
     Also shown is that the hearing device  121  is inserted in the right ear canal  302 . Acoustic sounds from the surroundings passes the hearing device  121  as shown by arrow  602  which extends towards the eardrum  304  from an outer periphery of the ear canal  302 . 
       FIG.  10    shows a flowchart for the third session. At the third session, which may or may not follow the first session and/or the second session, the method  1000  starts at step  1001  e.g. in response to a user tapping, on a touch-sensitive display of the electronic device, an affordance for activating an application or in response to having completed the first session or second session. At step  1002  a user interface screen, UI-3, e.g. including messages  801 ,  802  and  809 . Thereby the user is given instructions about what to do during the second session. At step  1003  the audio test signal is communicated to the user via the headphones one band, B(n), at a time. The method later reverts to step  1003  to communicate another band-limited portion of the audio test signal to the user. The band-limited portions may be enumerated n=[1 . . . N] e.g. n=[1,2,3,4,5]. 
     At step  1004 , the user&#39;s second balance input is received. The input may be given via a slider, e.g. slider  807 , or another variable input e.g. a rotatable wheel. The gain values of the first gain stage and/or the second gain stage may be set in accordance with a value from the slider. Once the user is satisfied that the loudness is perceived as being equal at both ears, the user may give a second accept input e.g. via button  806  whereby the method proceeds to step  1005 , where the user&#39;s third accept input is received. The method then proceeds to step  1006  to store the first gain value for band B(n). The method may then revert to step  1003 , via step  1007  (N), and continue the method as described above for a next band-limited portion. 
     When all band-limited portions have been communicated to the user and the user has given the corresponding inputs, second gain values have been determined for all of the multiple bands. Then, the method determines at step  1007  to proceed to another session or to communicate to the user that the session or sessions is/are completed (Y). 
       FIG.  11    shows a time-frequency chart for an audio test signal. The audio test signal is shown in a time-frequency chart  1101 , wherein the abscissa  1103  represents time or time indexes and wherein the ordinate  1102  represents frequencies or frequency indexes. Along the ordinate is indicated three bands, enumerated B1, B2 and B3, respectively. The bands are shown as being non-overlapping bands in terms of frequency, but they may overlap at least to a certain degree. Along the abscissa is indicated points in time t 0 , t 1 , t 2 , t 3 , t 4  and t 5  and periods of time T1, T2 and T3. For instance, T1 runs from t 0  to t 1 . The audio test signal is divided in band-limited portions  1105 ,  1106  and  1107 . The hatched portions indicate amplitude levels which can be heard by an average person with normal hearing, whereas the white areas indicate amplitude levels which is much lower e.g. much below an audible level or at a noise floor. 
     The band-limited portions of the audio test signal are separated in time. The duration of time from one period, e.g. T1, to the next, e.g. T2, may depend on a user&#39;s response time and duration of a pause between the sessions. The duration of the band-limited portions depends on how long time the user takes to adjust and decide that loudness at both ears is the same or substantially the same. Generally, the more band-limited portions of the audio test signal, the longer it takes for a user to complete a session. In some aspects, the user is presented with the option to continue at additional bands, e.g. at additional, narrower bands or to stop. The option to stop can be given e.g. only after a predefined number of bands, e.g. three bands, have been presented. 
     The audio test signal may be distributed at frequencies between e.g. 20 Hz and 12 kHz or between e.g. 20 Hz and 20 kHz. 
     Also shown is an example of arrays  1104  and  1105  comprising first gain values G L (1), G L (2), and G L (3) and second gain values G R (1), G R (2), and G R (3). The gain values are associated with the respective bands B1, B2 and B3. 
       FIG.  12    shows a bank of gain filters for deploying flat insertion gain filters. The flat insertion gain filters are set to have a gain corresponding to the first gain values and second gain values e.g. from the arrays  1104  and  1105 . The bank of gain filters may also be denoted a set of gain filters. The gain filters may be implemented as time-domain filters or as frequency-domain filters e.g. in a short-time frequency domain. 
     The gain filters  1201 ,  1202  and  1203  represents an example wherein three bands are used. Thus, there may be additional or fewer filters if additional or fewer bands are used. Each gain filter  1201 ,  1202  and  1203  comprises a filter section  1207 ,  1208  and  1309  and a respective gain stage  1204 ,  1205  and  1206 . 
     A combiner  1210 , e.g. an adder, combines outputs from the respective filters. 
     The bank of gain filters may implement the gain values determined in accordance with the method to enable deployment of flat insertion gain filters, or rather the gain values for the gain filters, at one or both of the first hearing device and the second hearing device. 
       FIG.  13    shows a flowchart for an embodiment of the method. In step  1301  the application starts, and the user may connect to specific headphones and/or hearing devices for use during the sessions. Step  1301  may also include enabling first communication, to the pair of headphones  120  and enabling second communication to the first hearing device  120  and/or the second hearing device  121 . 
     The methods  400 ,  700  and  1000  may be selectively performed at steps  1302 ,  1303  and  1304 , respectively. Thus, the first session, the second session and the third session may be performed selectively e.g. depending on an assumption of symmetric hearing and/or whether gain values are to be obtained for one or a pair of hearing devices. 
     At step  1305 , preferably when one or more of the sessions has/have been completed to obtain first gain values and/or second gain values and/or third gain values, the gain values can be deployed to one or more flat insertion gain filter(s) for or at a hearing device. 
       FIG.  14    shows embodiments of a pair of headphones and a pair of hearing devices. The pair of headphones  1401  comprises a headband  1404  carrying a left ear-cup  1402  and a right ear-cup  1403  which may also be designated ear-pieces. The pair of hearing devices  1410 , e.g. in the form of earphones comprises a left earpiece  1411  and a right earpiece  1412 . The pair of headphones  1401  is an example of headphones  130 . The hearing devices  1410  are examples of hearing devices  120 ;  121 . The ear-cups  1402  and  1403  each comprises a cushion  1405  and an enclosed space  1406  established between the ear-cup and the user. The enclosed space is sufficiently large that the hearing devices  1411  and  1412  can be accommodated while the headphones are worn on the user&#39;s head and while the hearing devices  1411  and  1412  or one of them are/is inserted in the user&#39;s respective ear canals. 
     For the pair of hearing devices  1410 , they each comprise a protrusion  1413  e.g. for accommodating an acoustic input transducer, e.g. one or more microphones. The acoustic output transducers of the hearing devices can emit sound through openings  1414  which face the user&#39;s eardrum, when inserted in the user&#39;s ear canal. 
     The term ‘reproduced signal’ refers to a signal which is presented to the user of the hearing device e.g. via a small loudspeaker, denoted a ‘receiver’ in the field of hearing devices. The ‘reproduced signal’ may include a compensation for a hearing loss or the ‘reproduced signal’ may be a signal with or without compensation for a hearing loss. 
     In some aspects, one or both of the hearing devices are configured to compensate for a hearing loss. In some aspects the electronic hearing device(s) is/are configured without compensation for a hearing loss. A hearing device may be configured to one or more of: protect against loud sound levels in the surroundings, playback of audio, communicate as a headset for telecommunication, and to compensate for a hearing loss. 
     Generally, a hearing device may also be designated a listening device.