METHOD OF ADJUSTING A HEARING INSTRUMENT

Abstract

The present invention provides a method of adjusting a hearing instrument (1) that is at least partially insertable into an ear canal (2), the hearing instrument (1) comprising at least two microphones (3;4), the method comprising the steps of: estimating the relative microphone location effect for each of the microphones (3;4);estimating the feedback stability for each of the microphones (3;4);determining the optimum proportion and phase of the signals of the microphones (3;4) to be used in an omni-directional mode; andsetting the optimum proportion and phase of the signals of the microphones (3;4). Thus, the present invention takes into account the acoustical stability of each of the microphones in order to optimally combine the microphones to achieve an optimal omni-directional performance if desired by the user of the hearing instrument

Description

DESCRIPTION OF THE DRAWINGS

For purpose of facilitating and understanding of the invention, a preferred embodiment thereof is illustrated in the accompanying drawing to be considered in connection with the following description. Thus the invention may be readily understood and appreciated.

FIG. 1 schematically shows a partial cross-section of the external ear with a hearing instrument partially inserted into the ear canal.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, the schematic drawing of an ITE hearing aid 1 at least partially inserted into the ear canal 2 is shown. The hearing aid comprises two microphones 3 and 4, located on the front side of the shell of the hearing aid 1. Both microphones 3 and 4 are connected to an amplifying processing unit 5, arranged within the shell of the hearing aid 1. This amplifying processing unit 5 drives a receiver 6 which is acoustically coupled to the ear canal 2 via a conduct 7.

The hearing aid 1 further comprises a venting canal 8 that connects the ear canal 2 with the environment.

The influence of the pinna 9, surrounding the front side of the shell of the hearing aid 1, to the microphones 3 and 4 are shown by arrows symbolizing the path of the environmental sound S. This sound will arrive at the microphones both directly as well as reflected by the pinna 9.

If the user of the hearing aid 1 wants to switch from the regular directional use to the omni-directional use, in one embodiment, the better of the two microphones 3 and 4 remains connected to the amplifying processing unit 5 and the other microphone will be disconnected from the amplifying processing unit 5.

This switching is performed i.e. by using a switching unit as described in EP 1 221 276.

In another embodiment of the present invention, both microphones 3 and 4 remain connected to the amplifying processing unit 5. The amplifying processing unit 5 will set only one of those microphones active for determined ranges of frequencies, i.e. by applying respectively set filters. As an example it thus may be the case that the first microphone 3 is activated for low frequencies and the second microphone 4 is activated for high frequencies, providing an even better acoustic performance than using only one microphone for the whole range of frequencies.

The present solution advantageously takes the acoustical stability into account when combining the two microphones or selecting one of the two microphones for omni-directional use. Therefore the better microphone will be selected and thus a higher stable gain and less feedback related problems will be achieved for hearing devices with at least two microphones for the omni-directional mode.

Claims

1. Method of adjusting a hearing instrument (1), the hearing instrument (1) comprising at least two microphones (3;4) and an amplifying processing unit (5), the method comprising the steps of: estimating the relative microphone location effect for each of the microphones (3;4);estimating the feedback stability for each of the microphones (3;4);determining the microphone (3; 4) with the better feedback stability to be used in an omni-directional mode.

2. The method of claim 1, comprising further the steps of: determining the optimum proportion and phase of the signals of the microphones (3;4) to be used in an omni-directional mode; andsetting the optimum proportion and phase of the signals of the microphones (3;4).

3. The method of claim 2, wherein the determination of the optimum proportion and phase of the signals of the microphones (3;4) will be made as a function of frequency and the optimum proportion and phase of the signals of the microphone will be set and modified accordingly.

4. The method of claim 1, wherein the relative microphone location effect is estimated by taking into account the different contributions of reflected sound by the pinna (9).

5. The method of claim 1, wherein the feedback stability for the microphones (3;4) is estimated by performing measurements on the ear of an individual user during the fitting process of the hearing instrument (1).

6. The method of claim 1, wherein the feedback stability for the microphones (3;4) is estimated based on geometrical data of the location of the microphones (3;4) and vent (8) of the hearing instrument (1).

7. The method of claim 1, wherein the best microphone (3;4) is determined and is selected as the only microphone (3;4) to be used in an omni-directional mode.

8. The method of claim 7, wherein the best microphone (3;4) is determined by weighting maximum stable overall amplifications as a function of frequency and selecting the most stable amplification.

9. The method of claim 8, wherein the weighting is done by a predefined rule that is independent of individual hearing loss.

10. The method of claim 8, wherein the weighting is done by a predefined rule that is dependent on individual hearing loss.

11. The method of claim 7, wherein the selection of the better microphone is done by switching the operative connection of the microphones (3,4) with the amplifying processing unit (5) to the previously determined better microphone only (3;4).

12. Applying the method of any of claims 1 to 11 to a hearing instrument that is at least partially insertable into an ear canal.