Measuring box for a hearing apparatus and corresponding measuring method

Abstract

The size of measuring boxes for hearing apparatuses and in particular for hearing devices is to be reduced, with the efficiency of the measuring box in respect of attenuating interference noises being maintained or improved. A measuring box is thus proposed, which comprises an interference signal recording facility for recording an interference signal. Furthermore, provision is made in the measuring box for a signal generating facility to generate a compensation signal which is phase-opposed to the recorded interference signal, so that the interference signal can be compensated for by the compensation signal. The interference noise attenuation is thus achieved here by an electronic active part, so that the quality demands on the measurement space can be reduced and its size thereby decreased as well.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described in more detail with reference to the appended drawings, in which;

FIG. 1 shows a simplified diagram of a measuring box according to the invention for the case in which no wanted signal is applied, and

FIG. 2 shows a simplified diagram of a measuring box for the simultaneous application of a wanted signal.

DETAILED DESCRIPTION OF THE INVENTION

The exemplary embodiments illustrated in more detail below represent preferred embodiments of the present invention.

According to the basic concept of the present invention, the ambient noise attenuation is achieved by means of a measuring box having an active system. A system of this type is shown schematically in FIG. 1. The system is to generate an inversely phased signal in the interior of the measuring box, said signal otherwise corresponding precisely to the ambient noise N permeating into the measuring box, said ambient noise N originating from the interference sound source 1.

The overall measuring box not only comprises a passive measurement space 2 here, but also an active electronics part 3, which can be referred to as an ambient noise reduction unit. This active part 3 records a signal of a reference or sound field microphone 4, which is positioned in the measurement space 2. The microphone signal is exclusively fed in the active part 3 to a control unit 5 including an adaptive filter. The output signal of the control unit 5 is forwarded to an amplifier 6 and is fed back from there to the control unit within the active part 3. The output signal of the amplifier 6 is used to control a loudspeaker 7, which is arranged in the measurement space 2.

On the basis of the interference sound N, which is recorded by the microphone 4 at the measuring or reference point in the measurement space 2, a signal —N, which is phase-opposed to the interference sound N, is generated in the measurement space with the aid of the interference noise reduction unit 3 and the loudspeaker 7. The interfering ambient noise at the measurement site 8 is herewith quenched.

The interference noise N is compensated for and quenched according to the example in FIG. 1 by means of a monitoring microphone 4, which records the ambient sound at the measuring point 8. Alternatively or in addition, an ambient microphone can also be attached to the exterior of the measuring box or of the measurement space 2 respectively, said ambient microphone continually measuring the ambient noises (cf. FIG. 2).

This method and respectively measuring system presented with reference to FIG. 1 is particularly suited to noise measurements, since a test signal need not be generated there simultaneously. In such cases only the background noises of a hearing device for instance are to be measured in a noise-free environment.

The significantly more complex case would be the reduction of the ambient noise whilst simultaneously applying a test signal. A measuring box which is suited to this situation is depicted in FIG. 2. A measuring microphone 4 is also arranged here in the measurement space 2 of the measuring box, said measuring microphone measuring the sound at the measurement point 8. The measurement signal S_m of the measuring microphone 4 is on the one hand directed outwards and is fed on the other hand to a control unit 11 within an active part 10 for ambient noise suppression purposes.

A wanted signal S₁ is supplied by way of an input of the active part 10. A generator 12 generates a compensation signal and is to this end controlled by the control unit 11, which supplies a corresponding coefficient. The output signal of the generator 12 is applied to the wanted signal S₁ in an adder 13. The total signal is fed to a filter H₂, which is used to compensate for said wanted signal portion, which still arrives at the exterior microphone 9. The filter H₂ is likewise controlled by the control unit 11 with corresponding coefficients.

The exterior microphone 9 first and foremost records the interference sound from the interference sound source 1. The output signal of the exterior microphone 9 is fed in the active part 10 to a further filter H_N. This filter H_N is used to reduce the interference signal level, since this is higher on the outside than in the interior of the measurement space 2. This filter also contains its coefficients from the control unit 11.

The output signals of the two filters H₂ and H_N are added in an adder 14 and the total signal is fed to an amplifier 15 as well as to the control unit 11. The output signal of the amplifier 15 is also used to control the loud speaker 7.

The recorded ambient noise is thus added here to the actual wanted signal S₁ by way of a special filter H_N but is also fed separately into the measurement space 2. Such cases can involve both a quasi static (calibrated) system, with which the interference sound is always the same, or an adaptive, self-controlling system, with which the filter is permanently adjusted.

If coils are used in place of the microphone 4 and the loudspeaker 7, electromagnetic interferences from the environment can also be compensated for. The coils can naturally also be used at the same time as the microphone—loudspeaker system, so that both an acoustic and an electromagnetic compensation can be implemented. The electromagnetic measurements and respectively compensations dispense with the need for a complex and expensive electromagnetic shielding of the measuring box.

By using an additional microphone 9 and an additional coil respectively besides the measurement microphone 4 and a measurement coil respectively for directly capturing the interference signal, the risk no longer exists, when reducing the interferences, of parts of the wanted signal and test signal respectively being quenched.

Claims

1.-11. (canceled)

12. A measuring box for calibrating a hearing apparatus inserted into the measuring box, comprising: an interference signal recording device that records an interference signal; anda signal generating device that generates a compensation signal that is phase-opposed to the recorded interference signal to compensate the recorded interference signal.

13. The measuring box as claimed in claim 12, wherein the interference signal and the compensation signal comprise acoustic signals.

14. The measuring box as claimed in claim 13, wherein the interference signal recording device comprises a microphone.

15. The measuring box as claimed in claim 13, wherein the signal generating device comprises a loudspeaker.

16. The measuring box as claimed in claim 12, wherein the interference signal and the compensation signal comprise electromagnetic signals.

17. The measuring box as claimed in claim 16, wherein the interference signal recording device comprises a receiving coil.

18. The measuring box as claimed in claim 16, wherein the signal generating device comprises a transmitting coil.

19. The measuring box as claimed in claim 12, wherein the interference signal and the compensation signal comprise both acoustic and electromagnetic signals.

20. The measuring box as claimed in claim 19, wherein the interference signal recording device comprises a microphone and a receiving coil.

21. The measuring box as claimed in claim 19, wherein the signal generating device comprises a loudspeaker and a transmitting coil.

22. The measuring box as claimed in claim 12, wherein the signal generating device further generates a measuring signal that is added to the compensation signal.

23. The measuring box as claimed in claim 12, wherein the interference signal recording device is arranged in the measuring box.

24. The measuring box as claimed in claim 12, wherein the interference signal recording device is arranged outside the measuring box and comprises a filter for reducing a level of the interference signal and fed the filtered signal to the signal generating device.

25. A method for calibrating a hearing apparatus in a measuring box, comprising: recording an interference signal;generating a compensation signal that is phase-opposed to the recorded interference signal to compensate the recorded interference signal; andcalibrating the hearing apparatus in the measuring box having the compensated interference signal.

26. The method as claimed in claim 25, wherein the interference signal and the compensation signal comprise acoustic signals.

27. The method as claimed in claim 25, wherein the interference signal and the compensation signal comprise electromagnetic signals.

28. The method as claimed in claim 25, wherein the interference signal and the compensation signal comprise acoustic and electromagnetic signals.

29. The method as claimed in claim 25, further comprising generating a measurement signal and adding the measurement signal to the compensation signal.

30. The method as claimed in claim 25, wherein the interference signal is recorded in the measuring box.

31. The method as claimed in claim 25, wherein the interference signal is recorded outside the measuring box and filtered for generating the compensation signal.