Hearing aid having plural microphones and a microphone switching system

• US 6,327,370 B1
• Filed: 07/24/2000
• Issued: 12/04/2001
• Est. Priority Date: 04/13/1993
• Status: Expired due to Fees

• Current Assignee: Etymotic Research Incorporated
• Original Assignee: Etymotic Research Incorporated
• Inventors: Killion, Mead, Allen, Jont, Waldhauer, Fred, Wittkowski, Johannes, Goode, Richard
• Primary Examiner(s): LE, HUYEN D
• Application Number:
  US09/624,805
• Time in Patent Office: 498 Days
• Field of Search: 381/312, 381/313, 381/322, 381/327, 381/328, 381/330, 381/355, 381/356, 381/357, 381/358, 381/FOR.128, 381/FOR.127, 381/FOR.135, 381/FOR.133
• US Class Current: 381/313
• CPC Class Codes: H04R 25/407 Circuits for combining signals of a plurality of transducers
• CPC Class Codes: H04R 25/43 Electronic input selection or mixing based on input signal analysis, e.g. mixing or selection between microphone and telecoil or between microphones with different directivity characteristics H04R25/407 takes precedence
• CPC Class Codes: H04R 29/005 Microphone arrays
• CPC Class Codes: H04R 29/006 Microphone matching
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A hearing aid apparatus is disclosed that employs both an omnidirectional microphone and at least one directional microphone of at least the first order. The electrical signals output from the directional microphone are supplied to an equalization amplifier which at least partially equalizes the amplitude of the low frequency electrical signal components of the electrical signal with the amplitude of the mid and high frequency electrical signal components of the electrical signals of the directional microphone. A switching circuit accepts the signals output from both the omnidirectional microphone and the directional microphone. The switching circuit connects the signal from the omnidirectional microphone to an input of a hearing aid amplifier when the switching circuit is in a first switching state, and connects the output of the equalization circuit to the hearing aid amplifier input when the switching circuit is in a second switching state. The switching circuit may be automatically switched in response to sensed ambient noise levels.

Claims

1. An in-the ear hearing aid apparatus comprising:

a faceplate having first, second and third faceplate sound openings;

a directional microphone having a single directional microphone housing, first and second microphone sound openings located in said directional microphone housing, and a diaphragm located in said housing dividing said directional microphone housing into a first chamber and a second chamber;

an omnidirectional microphone having a single omnidirectional microphone housing, a third microphone sound opening located in said omnidirectional microphone housing, and a diaphragm located in said omnidirectional microphone housing, said omnidirectional microphone housing being independent of said directional microphone housing;

a first sound passage acoustically coupling sound energy from said first faceplate sound opening in said faceplate to said first chamber of said directional microphone housing via said first microphone sound opening in said directional microphone housing;

a second sound passage acoustically coupling sound energy from said second faceplate sound opening in said faceplate to said second chamber of said directional microphone housing via said second microphone sound opening in said directional microphone housing;

a third sound passage acoustically coupling sound energy from said third faceplate sound opening in said faceplate to said diaphragm located in said omnidirectional microphone housing via said third microphone sound opening in said omnidirectional microphone housing, said third sound passage being independent of both said first and second sound passages;

a switch for selecting between an output generated by said directional microphone and an output generated by said omnidirectional microphone; and

a housing having said faceplate mounted thereon, said housing being sized to fit within the ear of a hearing aid wearer and containing said omnidirectional microphone, said directional microphone and at least a portion of said switch.

2. The hearing aid apparatus of claim 1 wherein said switch is manually actuatable by a wearer of said hearing aid apparatus.

3. The hearing aid apparatus of claim 1 wherein said switch is automatically actuatable in response to a reference signal falling below a predetermined threshold.

4. The hearing aid apparatus of claim 3 wherein the reference signal is ambient noise level and the predetermined threshold is 65 dB.

5. The hearing aid apparatus of claim 1 wherein at least a portion of said switch is accessible to the hearing aid wearer for switching between the output generated by said directional microphone and the output generated by said omnidirectional microphone.

6. The hearing aid apparatus of claim 5 wherein said at least a portion of said switch accessible to the hearing aid wearer is located on said faceplate.

7. An in-the-ear hearing aid apparatus comprising:

an outer surface having first, second and third sound openings;

a directional microphone having a single directional microphone housing and a diaphragm located in said directional microphone housing, said diaphragm having a first side and a second side;

an omnidirectional microphone having a single omnidirectional microphone housing and a diaphragm located in said omnidirectional microphone housing, said omnidirectional microphone housing being independent of said directional microphone housing;

a first sound passage acoustically coupling sound energy from said first opening in said outer surface to said first side of said diaphragm located in said directional microphone housing;

a second sound passage acoustically coupling sound energy from said second opening in said outer surface to said second side of said diaphragm located in said directional microphone housing;

a third sound passage acoustically coupling sound energy from said third opening in said outer surface to said diaphragm located in said omnidirectional microphone housing, said third sound passage being independent of both said first and second sound passages;

a switch for selecting between an output generated by said directional microphone and an output generated by said omnidirectional microphone; and

a housing having said outer surface, said housing being sized to fit within the ear of a hearing aid wearer and containing said omnidirectional microphone, said directional microphone and at least a portion of said switch.

8. The hearing aid apparatus of claim 7 wherein said switch is manually actuatable by a wearer of said hearing aid apparatus.

9. The hearing aid apparatus of claim 7 wherein said switch is automatically actuatable in response to a reference signal falling below a predetermined threshold.

10. The hearing aid apparatus of claim 9 wherein the reference signal is ambient noise level and the predetermined threshold is 65 dB.

11. The hearing aid apparatus of claim 7 wherein at least a portion of said switch is accessible to the hearing aid wearer for switching between the output generated by said directional microphone and the output generated by said omnidirectional microphone.

12. The hearing aid apparatus of claim 11 wherein said at least a portion of said switch accessible to the hearing aid wearer is located on said outer surface.