Method for operating a hearing system, a hearing system and a fitting system

Abstract

A method for operating a hearing system worn by a user, the hearing system being a binaural hearing system including first and second hearing aids and being prepared for processing a sound. The processing includes a beamforming which can be adjusted to at least a first beamforming mode and a second beamforming mode. The method includes receiving sound by the hearing system, determining whether the beamforming is to be adjusted to the first beamforming mode or the second beamforming mode and adjusting the beamforming accordingly and generating a processed sound, and presenting the processed sound to the user.

Claims

1. A method for operating a hearing system (10) worn by a user (U), said hearing system (10) being a binaural hearing system (10) comprising a first and second hearing aids (12L,12R), said hearing system (10) being prepared for processing a sound, said processing comprising a beamforming which can be adjusted to at least a first beamforming mode and a second beamforming mode, said method comprising: receiving sound by the hearing system; determining whether said beamforming is to be adjusted to the first beamforming mode or the second beamforming mode and adjusting the beamforming accordingly and generating a processed sound; presenting the processed sound to the user (U); wherein said first beamforming mode substantially preserves one or more binaural cues comprised in said sound whereas the second beamforming mode modifies the one or more binaural cues comprised in said sound, and wherein the determining depends on a binaural performance level of the user (U), said binaural performance level being indicative of the ability of the user (U) to distinguish binaural cues of sounds, wherein: the binaural performance level is assessed during a fitting session, assessing the binaural performance level comprises conducting a psychoacoustic test of a binaural masking threshold, and the psychoacoustic test comprises one of: measuring a Binaural Masking Level Difference, BMLD, experienced by the user (U), and measuring a Binaural Masking Time Difference, BMTD, experienced by the user (U).

2. The method of claim 1, wherein said binaural cues are one of: a latency between the sound arriving at a right and left ear of the user (U), a sound pressure level difference between the sound arriving at the right and left ear of the user (U), a loudness difference between the sound arriving at the right and left ear of the user (U), and a frequency response difference between the sound arriving at the right and left ear of the user (U).

3. The method of claim 2, wherein modifying one or more binaural cues comprises reducing one or more binaural cues.

4. The method of claim 1, wherein the second beamforming mode substantially preserves at least one binaural cue, said at least one binaural cue being different from the one or more binaural cues which are modified.

5. The method of claim 2, wherein modifying one or more binaural cues comprises one of: enhancing the one or more binaural cues, introducing the one or more binaural cues, and converting the one or more binaural cues.

6. The method according to claim 1, wherein the binaural performance level is frequency dependent.

7. The method according to claim 1, wherein the fitting session comprises preconfiguring the hearing system (10).

8. The method according to claim 1, wherein the binaural performance level is assessed at least in a first frequency-range and a second frequency-range.

9. The method according to claim 8, wherein the first frequency-range is above 1 kHz and the second frequency-range is below 2 kHz.

10. The method according to claim 1, wherein the binaural performance level is stored in the hearing system (10) as a default value.

11. The method of claim 10, wherein the default value is dependent on a hearing loss of the user (U).

12. The method according to claim 1, wherein determining comprises an evaluating of the sound.

13. The method according to claim 12, wherein said evaluating is performed by the user (U) via a user interface.

14. The method according to claim 12, wherein said evaluating comprises classifying the sound by the hearing system (10).

15. The method according to claim 14, wherein said classifying comprises detecting at least one of: an acoustic diffusiveness of the sound, a reverberant signal comprised in the sound, occurrence of lateral jammers in the sound.

16. The method according to claim 1, wherein the beamforming comprises a preprocessing of the sound, said preprocessing being one of: a noise cancelling, and an automatic gain control.

17. The method according to claim 1, further comprising the step of: if the binaural performance level is determined to be poor, switching the hearing system on full beamformer and applying processing means adapted to preserve and/or enhance Interaural Level Differences, ILDs.

18. The method according to claim 17, wherein the processing means comprises at least one of ITD-to-ILD conversion at low frequencies, ILD transposition from high to low frequencies, ILD enhancement, and AGC coupling.

19. The method according to claim 17, wherein the processing means is provided with speech input signals before beamforming and applies the processing result after beamforming.

20. A hearing system (10) to be worn by a user (U), said hearing system (10) comprising a first and a second hearing aids (12L,12R) and a user interface, said hearing system (10) being a binaural hearing system (10) prepared for processing a sound, said processing comprising a beamforming which can be adjusted to at least a first beamforming mode and a second beamforming mode, said hearing system comprising: a means for evaluating said sound; a determining means for determining whether said beamforming is to be adjusted to the first beamforming mode or the second beamforming mode, and adjusting the beamforming accordingly; a processing means for executing the determined beamforming mode in the hearing system; wherein said first beamforming mode substantially preserves one or more binaural cues comprised in said sound whereas the second beamforming mode modifies the one or more binaural cues comprised in said sound, and wherein the determining depends on the evaluation of the sound and of a binaural performance level of the user (U), said binaural performance level being indicative of the ability of the user to distinguish binaural cues of sounds, wherein the binaural performance level is assessed during a fitting session, wherein assessing the binaural performance level comprises conducting a psychoacoustic test of a binaural masking threshold, and wherein the psychoacoustic test comprises one of: measuring a Binaural Masking Level Difference, BMLD, experienced by the user (U), and measuring a Binaural Masking Time Difference, BMTD, experienced by the user (U).

21. A fitting system (FS) adapted for fitting the hearing system (10) according to claim 20.

22. The fitting system (FS) according to claim 21 configured for executing a psychoacoustic test to determine binaural hearing ability of the user (U) wearing the hearing system (10).

23. The fitting system (FS) according to claim 21, adapted to determine default values for the binaural performance level from a hearing loss.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is further described with reference to the accompanying drawings jointly illustrating various exemplary embodiments which are to be considered in connection with the following detailed description. What is shown in the figures is:

(2) FIG. 1 schematically depicts a binaural hearing system comprising a left hearing aid and a right hearing aid;

(3) FIG. 2 schematically depicts a method for operating the binaural hearing system according to a first embodiment; and

(4) FIG. 3 schematically depicts a method for operating the binaural hearing system according to a second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 schematically depicts a binaural hearing system 10 comprising a left hearing aid 12L and a right hearing aid 12R. The exemplarily shown binaural hearing system 10 offers binaural processing of sound in order to improve e.g. speech understanding in noisy communication situations.

(6) Each of said hearing aids 12L, 12R comprises a processor 14 connected to a battery 16, respectively. Further comprised is a microphone arrangement 18, which can preferably comprise two microphones M1, M2 for picking up sound. The sound can be processed by the processor 14 and output to the ear canal of the user by means of a receiver 20. Both hearing aids 12L, 12R are operatively connected to each other. The connection can be established based on a wireless technique, e.g. via a binaural link BL established by means of a wireless interface 22 comprised in each of said hearing aids 12L, 12R, respectively. In another example, the connection can be established based on a wired technique.

(7) As mentioned above, the binaural hearing system 10 offers binaural processing of sound. The algorithm provides a solution to improve intelligibility in complex listing situations for the hearing system user by means of binaural hearing, wherein the algorithm applied can involve predefined directional characteristics and a combination of signals which are input into both hearing aids 12L, 12R.

(8) In operation, the hearing system 10 combines the signal of the two microphone systems in the left and right hearing aids 12L, 12R via the binaural link BL and then processes them. In the algorithm, a tradeoff can be made between strong directivity versus preserving binaural cues to the user. The distance between the left and right microphones M1 and M2 in each hearing aid 12L, 12R allows to differentiate between the individual microphone signals from different points in the environment, e.g. in a room, allowing to provide a more effective spatial effect, in particular at lower frequencies. This is important in terms of spatial perception and localization.

(9) A binaural beamformer with broadband diotic output, which provides identical signals on both ears, provides good performance with respect to directivity index improvement. Further, improved suppression in a diffuse noise field can be achieved. However, identical directional characteristics on the right end left side would result in a diotic perception of sound that lacks directional information for lateralization. To put it in other words, this approach results in loss of binaural cues comprising Interaural Time Difference (ITD) and Interaural Level Difference (ILD). Users have reported that this provides unnatural listening condition.

(10) One solution might be to introduce a band specific mixing of ipsi- and contralateral signals in order to preserve some of the binaural cues. By applying a binaural beamformer in the lower frequencies, e.g. below 1-2 kHz, and a monaural beamformer in the higher frequencies, e.g. above 1-1.6 kHz, interaural level difference (ILD) due to the head shadow effect at higher frequencies are preserved. It is to be noted the frequencies set out above are only exemplary. However, binaural beamforming at higher frequencies only keeps interaural time differences (ITD) intact. There is no diagnostic known in the art that allows to predict which hearing system user will profit most from which kind of binaural processing. In other words, binaural beamforming known in the art is not individualized and fitted to the individual needs or preferences and binaural processing is not adapted to the acoustic environment depending on the diffusiveness of the sound field.

(11) FIGS. 2 and 3 schematically depict a method for operating the binaural hearing system 10 according to a first and second embodiments of the present invention. In the embodiment as shown in FIG. 2, the step of evaluating the acoustic environment is performed by classifying the acoustic environment by the hearing system 10, whereas FIG. 3 shows preconfiguring the hearing system 10 during a fitting session for assessing the binaural performance level.

(12) Referring back to FIG. 2, said figure schematically shows a method for operating the hearing system 10 in a reverberant environment, e.g. a room with solid walls W1, W2. This environment introduces acoustic diffusiveness of a sound output from a loudspeaker LS. A user U placed in this environment is wearing the hearing system 10 comprising the left and right hearing aids 12L, 12R. The user U is looking in a direction towards the center of the room (as indicated by a solid line arrow). The sound output from the loudspeaker LS reaches the hearing aids 12L, 12R directly (as indicated by dashed arrows) and indirectly (as indicated by dash-doted arrows) due to reflecting objects, i.e. the walls W1, W2. Both hearing aids 12L, 12R can communicate with each other via the binaural link BL, allowing to cooperatively process the input sound, e.g. by beamforming. The beamforming is used in order to reduce noise in the hearing aids 12L, 12R by focusing on the direction of the targeted sound output from the loudspeaker LS. In the shown example, by focusing towards the target sound, interfering noise can essentially be eliminated.

(13) In the embodiment as shown in FIG. 2, the beamforming mentioned above can be adjusted to a first beamforming mode and a second beamforming mode. In another example, the beamforming can be adjusted to more than two beamforming modi. The method evaluates the acoustic environment prevailing in the scenario as depicted in FIG. 2 comprising the reverberant sound. Based on the evaluation, the hearing system 10 determines whether the beamforming is to be adjusted to the first beamforming mode or the second beamforming mode. Said determining can be performed in one or both of the processors comprised in the hearing aids 12L, 12R (refer to FIG. 1). In the hearing system 10, the beamforming is adjusted according to the determining step. Further, the user U is presented the processed sound.

(14) According to the invention, on the one hand, the first beamforming mode substantially preserves one or more binaural cues comprised in the sound. On the other hand, the second beamforming mode modifies the one or more binaural cues comprised in said sound. In doing so, the determining depends on a binaural performance level of the user, wherein said binaural performance level indicates or rather being indicative of the user U ability to distinguish binaural cues of sounds. In an example, said binaural cues are a latency between the sound arriving at the right and left ear of the user. In another example said binaural cues are a sound pressure level difference between the sound arriving at the right and left ear of the user. In another example said binaural cues are a loudness difference between the sound arriving at the right and left ear of the user. In another example said binaural cues are a frequency response difference between the sound arriving at the right and left ear of the user. It is to be noted that at least some of the examples mentioned above can be combined.

(15) In the sound environment as depicted in FIG. 2, the evaluating step is performed by classifying the acoustic environment by the hearing system. In other words, the respective acoustic is picked up by the microphones of both hearing aids 12L, 12R in order to evaluate at least one of the acoustic diffusiveness of the sound, a reverberant signal comprised in the sound, and occurrence of lateral jammers in the sound. It is to be noted that the term “sound” means the (respective) sound prevailing in the acoustic environment.

(16) The hearing system can be controlled by a user interface, which is in the shown example an accessory device AC, which establishes a communication with the hearing system, e.g. via a wireless connection. The accessory device AC can be used to perform settings to the hearing system and/or to notify the user U about a status thereof via a display unit DU. In an example, the accessory device AC can be a smartphone or a touchscreen portable device.

(17) FIG. 3 schematically depicts a method for operating the binaural hearing system according to the second embodiment of the present invention. In this embodiment, the hearing system is preconfigured during a fitting session performed in a fitting system FS for assessing the binaural performance level. This fitting session is exemplified in the FIG. 3 as a binaural hearing test setup. During the fitting session, the user U is exposed to sounds generated by a test equipment of the fitting system FS. This test equipment comprises a plurality of circumferentially arranged loudspeakers LS1-LS8 for presenting test sounds to the user U. In an aspect, the test sounds can be presented to the user U via headphones HP1, HP2. In another aspect, the test sounds can be input to the left and right hearing aids 12L, 12R, directly. While the connection between the sound generator and the hearing aids 12L, 12R of the hearing system is shown to be a wired connection, said connection is preferably a wireless connection.

(18) The test sounds are generated by a sound generator SG comprised by the test equipment, wherein the sound generator SG supplies the test sounds to one of the loudspeakers LS1-LS8, the headphones HP1, HP2 and the left and right hearing aids 12L, 12R. The test equipment of the fitting system FS further comprises a user interface UI adapted to receive feedback input by the user U during the fitting session.

(19) During the fitting session, the binaural performance level is assessed by performing a psychoacoustic test of a binaural masking threshold. The assessment is preferably performed by supplying the test signal to the user by means of headphones configured to completely prevent crosstalk between both ears or rather sound sources (left/right).

(20) During the assessment, e.g. a N.sub.0S.sub.pi test primarily assesses the capability of the user to use Interaural Time Differences ITDs for binaural processing. Those users have to rely on Interaural Level Difference ILD as primary for localization. The psychoacoustic test comprises measuring a Binaural Masking Level Difference, BMLD, experienced by the user. Alternatively or as an option, the psychoacoustic test can comprise measuring a Binaural Masking Time Difference, BMTD, experienced by the user. The binaural performance level can be assessed in a first frequency-range and a second frequency-range, wherein the first frequency-range can be above 1 kHz and the second frequency-range can be below 2 kHz. Depending on the use-case, any other frequency-ranges can be used if necessary. The binaural performance level can be stored in the hearing system as a default value. This default value can depend on a hearing loss of the user U. In an example, the binaural masking level difference, BMLD, (N.sub.0S.sub.pi vs. N.sub.0S.sub.0) can be performed in a range between 200 and 1000 Hz. The BMLD measurement is a superior psychoacoustic test which is shown to be a good predictor for binaural integration.

(21) If the test reveals that the user U shows poor binaural processing capabilities, i.e. the test results in a low binaural performance level of the user, wherein the binaural performance level is indicative of the ability of the user to distinguish binaural cues of sounds, the hearing system can be configured to a strong broadband binaural beamforming mode with no or only little preservation of binaural cues. In doing so, the hearing system of the user U can be adjusted to the maximum binaural preprocessing since the “binaural processor of the user U” does not give him a significant benefit. However, if the test reveals that the user shows good binaural processing capabilities, i.e. the test results in a high binaural performance level of the user U, the beamformer is set to be less aggressive, such that more binaural cues of the signal are preserved.

(22) The evaluating step can be carried out or rather performed by the user in a respective environment the user is currently in. In this case, the evaluating step can be performed via the user interface. In an example, the user interface is a user control of the hearing aid, a remote control or a smartphone. In a preferred example, the evaluating step is performed via an app loaded and executable in the smartphone. The app can be configured such to display at least one preset button, slide control, etc. on the display of the smartphone as well as to allow the user to perform the evaluating step by adjusting the at least one preset button, slide control, etc. on the display of the smartphone, directly.