METHOD AND SYSTEM FOR PROVIDING HEARING ASSISTANCE TO A USER

Abstract

There is provided a method for providing hearing assistance to a user, comprising: capturing audio signals by a microphone arrangement (18) and transmitting the audio signals by a transmission unit (10) via a modulated wireless audio link (30) to a receiver unit (12) and receiving the audio signals at the receiver unit (12); analyzing the amplitude of the received audio signals by an analyzer unit (34) of the receiver unit (12); dynamically adjusting by a gain control unit (36) located in the receiver unit (12) the gain applied to the received audio signals according to the result of the analysis by the analyzer unit (34), wherein the gain is equal to or larger than a first value (GH) if the amplitude of the received audio signals is equal to or larger than a first threshold (U1H) and is reduced to a finite value less than said first value if the amplitude of the received audio signals is less than said first threshold (U1H); and stimulating the user's hearing by stimulating means (14, 16) worn at or in the user's ear according to the audio signals amplified according to the gain set by the gain control unit (36).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example of a wireless hearing assistance system according to the invention;

FIG. 2 is a block diagram of one example of the electronic module of the receiver unit;

FIG. 3 is a block diagram of an alternative example of the electronic module of the receiver unit;

FIG. 4 is an example of the expansion characteristic provided by the electronic module of the receiver unit, with the output amplitude being shown as a function of the received audio signal level; and

FIG. 5 shows an example of the gain applied by the electronic module of the receiver unit as a function of the amplitude of the received audio signal level.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram of a hearing assistance system comprising a transmission unit 107 a receiver unit 12 and an output transducer 14, 16 for stimulating a user's hearing.

The transmission unit 10 comprises a microphone arrangement 18, which preferably consists of two spaced-apart microphones for achieving acoustic beam forming, a transmitter module 20 and an antenna 22. The receiver unit 12 comprises an antenna 24 and an electronic module 26. The output of the receiver unit 12 may be directly connected to an output transducer 14. As a modification, the output transducer 14 may be part of receiver unit 12. According to an alternative embodiment, the receiver unit 12 may be connected—usually via an audio shoe—mechanically and electronically to a hearing instrument 28 comprising an output transducer 16. In this case the output of the receiver unit 12 will be connected to an audio input of the hearing instrument 28. According to an alternative embodiment, the elements of the receiver unit 12 may be integrated within the hearing instrument 28.

In any case, the output transducer 14, 16, which usually will be of the electro-acoustic type, i.e. a loudspeaker, will be worn at the user's ear. To this end, it could be located behind the ear (BTE), in the ear (IPE) or completely in the ear (CIC). Also the receiver unit 12 will be worn at or close to the user's ear.

The transmission unit 10 and the receiver unit 12 are adapted to establish a wireless audio link 30, usually an FM (frequency modulation) radio link between the transmission unit 10 and the receiver unit 12 for transmitting audio signals captured by the microphone 18 from the transmission unit 10 to the receiver unit 12. The signals received by the antenna 24 of the receiver unit 12 undergo signal processing in the electronic module 26 and finally are provided as audio signals to the output transducer 14, 16 for stimulating the user's hearing according to the audio signals received by the receiver unit 12.

An example of the electronic module 26 of FIG. 1 is shown in FIG. 2. The electronic module 26 comprises a demodulator 32, an analyzer unit 34 and a variable gain amplifier 36. The demodulator 32 has two outputs, one carrying the demodulated audio signal U1 received from the transmission unit 10, and the other one carrying an IF signal which is a down-conversion of the received radio signal to a lower intermediate frequency. The demodulated audio signal U1 is supplied to the variable gain amplifier 36 where it is amplified and delivered as an audio output signal U2 at the output 38 of the receiver unit 12 for being supplied to the output transducer 14 or to the audio input of the hearing instrument 28. The IF signal is supplied to the analyzer unit 34 by which the modulation width of the IF signal is measured. The modulation width of the IF signal is proportional to the amplitude of the demodulated audio signal U₁. The analyzer unit 34 serves to set the gain applied by the amplifier 36 according to the measured modulation width of the IF signal—and thus according to the amplitude of the demodulated audio signal. To this end, the analyzer unit 34 provides an output signal as a function of the measured modulation width of the IF signal in order to control the variable gain amplifier 36 accordingly.

FIG. 3 shows an alternative embodiment of the electronic module 26 wherein the analyzer unit 34 is provided with the demodulated audio signal U₁ rather than with the IF signal in order to directly analyze the amplitude of the demodulated audio signal U₁ for controlling the amplifier 36 accordingly.

FIG. 5 shows an example of the gain applied by the amplifier 36 as a function of the amplitude of the demodulated audio signal U₁ under the control of the analyzer unit 34. FIG. 4 shows the corresponding amplitude of the audio output signal U₂ as a function of the amplitude of the demodulated audio signal U₁. According to FIGS. 4 and 5 the gain is constant at a high value G_H=20 Log(2/U₁) if the amplitude of the demodulated audio signal U₁ is equal to larger than a threshold U_1H, while the gain is constant at a low value G_L=20 Log(U₂/U₁) if the amplitude of the demodulated audio signal U₁ is equal to or less than a lower threshold U_1L. If the amplitude of the demodulated audio signal U₁ is between the low threshold and the high threshold, the gain increases with increasing amplitude of the demodulated audio signal U₁, preferably at an expansion factor of 2:1, i.e. the output level U₂ increases by 2 dB each time the input level U₁ increases by 1 dB.

As an example, the dynamic range within which the gain is varied could be 12 dB. Preferably, the range of the gain variation is less than 20 dB in order to ensure that even for the lowest gain the user will be able to perceive a sound signal so that he does not get the feeling that the system does not work properly.

The time constants of the analyzer unit are selected such that for decreasing amplitude of the audio signal U₁ the gain applied by the amplifier 36 is reduced with a relatively long time constant of, for example, 100 msec, while in the case in which the amplitude of the audio signal U₁ is increasing, the gain applied by the amplifier 36 is increased quickly at a time constant of a few msec. Thereby it is ensured that for falling audio signal amplitude smooth transitions between different gains are made in order to avoid distortions while for rising audio signal amplitudes the gain is quickly increased to the necessary higher value so that the voice of the speaker using the microphone arrangement 18 will be captured by the output transducer 14, 16 almost immediately when the speaker starts speaking.

According to the invention, the gain applied to the audio signals received in the receiver unit 12 is varied dynamically according to the amplitude of the received audio signals measured by the analyzer unit in such a manner that for low input audio signal levels the audio signal output level is reduced with respect to the output level for high levels of the audio input signal, while maintaining the audibility of the demodulated signals even at relatively low audio input signals. Thereby both electronic noise present in the system at least at relatively large distances between the transmission unit 10 and the receiver unit 12 and surrounding acoustic noise picked up by the microphone 18 of the transmission unit can be reduced or eliminated while still an audible signal is presented to the user so that he does not have an uncomfortable feeling that the system sometimes does not work properly.

While various embodiments in accordance with the present invention have been shown and described, it is understood that the invention is not limited thereto, and is susceptible to numerous changes and modifications as known to those skilled in the art. Therefore, this invention is not limited to the details shown and described herein, and includes all such changes and modifications as encompassed by the scope of the appended claims.

Claims

1. A method for providing hearing assistance to a user, comprising: (a) capturing audio signals by a microphone arrangement and transmitting said audio signals by a transmission unit via a modulated wireless audio link to a receiver unit and receiving said audio signals at said receiver unit;(b) analyzing an amplitude of said received audio signals by an analyzer unit of said receiver unit;(c) dynamically adjusting by a gain control unit located in said receiver unit a gain applied to said received audio signals according to a result of an analysis by said analyzer unit, wherein said gain is equal to or larger than a first value if said amplitude of said received audio signals is equal to or larger than a first threshold and is reduced to a finite value less than said first value if said amplitude of said received audio signals is less than said first threshold; and(d) stimulating a hearing of said user by stimulating means worn at or in an ear of said user according to said audio signals amplified according to said gain set by said gain control unit.

2. The method of claim 1, wherein said gain is constant at said first value if said amplitude of said received audio signals is equal to or larger than said first threshold.

3. The method of claim 2, wherein said gain is constant at a second value lower than said first value, if said amplitude of said received audio signals is less than a second threshold which is lower than said first threshold.

4. The method of claim 3, wherein said gain increases with increasing amplitude of said received audio signals from said second value to said first value, if said amplitude of said received audio signals is between said first threshold and said second threshold.

5. The method of claim 4, wherein said gain increases at an expansion factor of 2:1 with an amplitude level of said received audio signals, if said amplitude of said received audio signals is between said first threshold and said second threshold.

6. The method of claim 1, wherein said gain is varied by said gain control unit within a dynamic range of 20 dB or less as a monotonous function of said amplitude of said received audio signals.

7. The method of claim 6, wherein said gain is varied by said gain control unit within a dynamic range of 12 dB or less as a monotonous function of said amplitude of said received audio signals.

8. The method of claim 1, wherein for decreasing amplitude of said received audio signals said gain is reduced by said gain control unit with a time constant between 50 and 300 msec.

9. The method of claim 1, wherein for increasing amplitude of said received audio signals said gain is increased by said gain control unit with a time constant between 1 and 10 msec.

10. The method of claim 1, wherein said analyzer unit analyses said amplitude of said received audio signals by measuring an amplitude of said audio signals after having been demodulated.

11. The method of claim 1, wherein said analyzer unit analyses said amplitude of said received audio signals by measuring an modulation width of an intermediate frequency signal having a frequency lower than a carrier of said received audio signals.

12. The method of claim 1, wherein said gain control unit is a variable gain amplifier.

13. The method of claim 1, wherein said stimulating means is part of a hearing instrument to which said receiver unit is mechanically and electrically connected.

14. The method of claim 1, wherein said stimulating means is part of a hearing instrument into which said receiver unit is integrated.

15. The method of claim 1, wherein said stimulating means is part of said receiver unit.

16. The method of claim 1, wherein said stimulating means is connected to said receiver unit.

17. The method of claim 1, wherein said analyzer unit outputs a gain control signal according to said result of said analysis and wherein said gain control signal is applied to said gain control unit.

18. The method of claim 1, wherein said microphone arrangement is part of said transmission unit.

19. The method of claim 1, wherein said stimulating means is a loudspeaker.

20. The method of claim 1, wherein said modulated wireless audio link is a Radio Frequency (RF) link.

21. The method of claim 20, wherein said Radio Frequency link is a Frequency Modulation (FM) link

22. A system for providing hearing assistance to a user, comprising a microphone arrangement for capturing audio signals; a transmission unit for transmitting said audio signals via a modulated wireless audio link to a receiver unit for receiving said audio signals; an analyzer unit located in said receiver unit for analyzing an amplitude of said received audio signals; a gain control unit located in said receiver unit for dynamically adjusting a gain applied to said audio signals according to a result of an analysis by the analyzer unit; wherein said gain control unit is designed such that said gain is equal to or larger than a first value if said amplitude of said received audio signals is equal to or larger than a first threshold and is reduced to a finite value less than said first value if said amplitude of said received audio signals is less than said first threshold; and means to be worn at or in an ear of said user for stimulating a hearing of said user according to said audio signals amplified according to said gain set by said gain control unit.