Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R25/00—Electric hearing aids
  • H04R25/40—Arrangements for obtaining a desired directivity characteristic
  • H04R25/407—Circuits for combining signals of a plurality of transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R2410/00—Microphones
  • H04R2410/01—Noise reduction using microphones having different directional characteristics
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R25/00—Electric hearing aids
  • H04R25/40—Arrangements for obtaining a desired directivity characteristic
  • H04R25/405—Arrangements for obtaining a desired directivity characteristic by combining a plurality of transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R25/00—Electric hearing aids
  • H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
  • H04R25/505—Customised settings for obtaining desired overall acoustical characteristics using digital signal processing

Definitions

• the present disclosure relates to hearing assistance devices, and in particular, to microphone placement in hearing assistance devices for controlled directivity.
• Hearing aids are one form of hearing assistance devices that are used to correct for hearing loss. Hearing aids provide amplification of sound in ranges of hearing loss; however, simply amplifying sound is not necessarily adequate. Hearing aids also frequently require special attention to reduction of feedback and to placement of one or more microphones for proper hearing.
• the behind-the-ear hearing aid (“BTE"), one or more microphones are found on the hearing aid enclosure that rests behind the ear.
• BTE behind-the-ear hearing aid
• Such devices do not have the benefit of the ear's anatomy for reflecting sound to a focal point, such as at the ear canal. Thus, such devices may receive sounds from a different set of angles than which is normally heard.
• the user In noisy environments, the user may have difficulty hearing due to the reception of noise generally about the user.
• the present disclosure provides various examples, some of which are apparatus, including: a hearing assistance device housing; a first directional microphone having first and second sound ports along a first axis, the first directional microphone producing a first audio signal; a second directional microphone having third and fourth sound ports along a second axis, the second directional microphone producing a second audio signal; and signal processing electronics for adjustment of phase and magnitude of first audio signal and the second audio signal, wherein the first, second, third, and fourth sound ports extend through the hearing assistance device housing.
• the first directional microphone and the second directional microphone are aligned such that the first axis and the second axis are at an angle greater than zero degrees, hi some examples, the first axis and the second axis are at 90 degrees, hi some examples, an omnidirectional microphone produces a third signal, and the signal processing electronics include adjustment of phase and magnitude of the third audio signal.
• the signal processing electronics include adjustment of phase and magnitude of the third audio signal.
• Various examples including, but not limited to, behind-the-ear, on-the- ear, over-the-ear, and in-the-ear hearing assistance devices are set forth.
• Various realizations include signal processing electronics using a digital signal processor, microprocessor are discussed.
• the directional microphones can have a variety of cardioid, supercardioid, dipole, and hypercardioid reception patterns in various combinations.
• an example includes an apparatus, having: a behind-the-ear hearing aid housing; a first directional microphone having first and second sound ports along a first axis, the first directional microphone producing a first audio signal; a second directional microphone having third and fourth sound ports along a second axis, the second directional microphone producing a second audio signal; a signal processor receiving the first audio signal and the second audio signal and adapted to adjust phase and amplitude of first audio signal and the second audio signal, and produce a summed signal; and a receiver (loudspeaker) to produce an audio signal based on the summed signal, wherein the first, second, third, and fourth sound ports extend through the hearing aid housing and wherein the first axis and second axis are offset by angle ⁇ .
• Various offsets including ninety degrees, and others, and various microphone orientations and offsets in the device are disclosed.
• the present subject matter also includes a method, including: applying an amplitude A and a phase ⁇ to a signal from a first directional microphone to produce a first signal; applying an amplitude C and phase ⁇ to a signal from a second directional microphone to produce a second signal, the first directional microphone and second directional microphone having axes that intersect at an angle ⁇ ; summing the first signal and the second signal to produce an output signal; and selecting values of A, C, ⁇ , " ⁇ and ⁇ to provide a desired reception pattern from a combination of signals from the first directional microphone and the second directional microphone.
• the method includes applying an amplitude B and phase a to a sound signal from an omnidirectional microphone to produce a third signal, and wherein the signal processing includes selecting values of B and a to provide the desired reception pattern.
• the summing includes producing magnitudes of the first signal and second signal; and adding the magnitudes.
• the summing includes adding the first signal and second signal using a complex addition process to create a complex sum; and producing a magnitude of the complex sum.
• FIG. 1 shows a plan view of a behind-the-ear hearing aid including microphone placements according to one embodiment of the present subject matter.
• FIG. 2 shows a plan view of a behind-the-ear hearing aid including microphone placements, according to one embodiment of the present subject matter.
• FIG. 3 shows a plan view of a behind-the-ear hearing aid including microphone placements, according to one embodiment of the present subject matter.
• FIG. 4 shows a dual directional microphone system, according to one embodiment of the present subject matter.
• FIG. 5 shows a microphone system including two directional microphones and an omnidirectional microphone, according to one embodiment of the present subject matter.
• FIG. 6 shows a microphone system including a directional microphone and an omnidirectional microphone, according to one embodiment of the present subject matter.
• FIG. 7 is a polar plot showing one example of an angular reception pattern for a system operating according to one embodiment of the present subject matter and for a particular group of parameters for that system.
• FIG. 8 is a polar plot showing one example of an angular reception pattern for a system operating according to one embodiment of the present subject matter and for a particular group of parameters for that system.
• FIG. 1 shows a plan view of a behind-the-ear hearing aid including microphone placements according to one embodiment of the present subject matter.
• the hearing assistance device 102 is a behind-the-ear (BTE) device, however, as stated above, the present subject matter can be applied to a variety of devices.
• BTE behind-the-ear
• the embodiment shown includes two directional microphones. Each directional microphone receives sound from a pair of sound ports. Thus, sound ports 1 and 2 are used by the first directional microphone and sound ports 3 and 4 are used by the second directional microphone, hi some embodiments, an omnidirectional microphone (not shown) is added to the combination.
• FIG. 1 shows a plan view of a behind-the-ear hearing aid including microphone placements according to one embodiment of the present subject matter.
• the hearing assistance device 102 is a behind-the-ear (BTE) device, however, as stated above, the present subject matter can be applied to a variety of devices.
• the embodiment shown includes two directional microphones. Each directional microphone receives
• FIG. 1 shows sound ports 1 and 2 being aligned along a first axis 104 and sound ports 3 and 4 aligned with a second axis 105.
• the zero degree reference 110 in all of the following plan views will be pointing downward, as shown. This reference is not an absolute direction and used only to illustrate various angles and positions of microphone components and sound reception polar patterns throughout.
• second axis 105 of sound ports 3 and 4 intersects first axis 104 of sound ports 1 and 2 at 90 degrees, hi this embodiment, axis 104 coincides with the axis bisecting the plan view of the device 102.
• the separation of the sound ports and intersection location of the sound port axes will not be uniform.
• the separation between sound ports 1 and 2 will be lesser than the separation between sound ports 3 and 4.
• the separation between sound ports 1 and 2 will be greater than the separation between sound ports 3 and 4.
• the separation between sound ports 1 and 2 will be equal to the separation between sound ports 3 and 4.
• the second axis will intersect the first axis at a location closer to sound port 1.
• the second axis will intersect the first axis at a location closer to sound port 2.
• the first axis will intersect the second axis at a location closer to sound port 3.
• the first axis will intersect the second axis at a location closer to sound port 4.
• any number of orientations of ports 1, 2, 3, and 4 are contemplated providing that the first axis and second axis intersect at 90 degrees.
• FIG. 2 shows a plan view of a behind-the-ear hearing aid including microphone placements, according to one embodiment of the present subject matter.
• the hearing assistance device 202 is a behind-the-ear (BTE) device, however, as stated above, the present subject matter can be applied to a variety of devices.
• BTE behind-the-ear
• the embodiment shown includes two directional microphones. In some embodiments, an omnidirectional microphone (not shown) is added to the combination.
• second axis 205 of sound ports 3 and 4 intersects first axis 204 of sound ports 1 and 2 at 90 degrees; however, in this embodiment, first axis 204 has been rotated by an acute angle relative to the axis 203 bisecting the plan view of the device 202.
• the separation of the sound ports and intersection location of the sound port axes will not be uniform.
• the separation between sound ports 1 and 2 will be lesser than the separation between sound ports 3 and 4.
• the separation between sound ports 1 and 2 will be greater than the separation between sound ports 3 and 4.
• the separation between sound ports 1 and 2 will be equal to the separation between sound ports 3 and 4.
• the second axis will intersect the first axis at a location closer to sound port 1. In various embodiments the second axis will intersect the first axis at a location closer to sound port 2. In various embodiments the first axis will intersect the second axis at a location closer to sound port 3. hi various embodiments, the first axis will intersect the second axis at a location closer to sound port 4.
• any number of orientations of ports 1, 2, 3, and 4 are contemplated providing that the first axis and second axis are at 90 degrees and the first axis is rotated by an acute angle ⁇ relative to the bisecting axis 203.
• the example shown in FIG. 2 is intended to demonstrate one configuration with a ⁇ of 45 degrees; however, it is understood that other values of ⁇ may be used without departing from the principles set forth herein.
• FIG. 3 shows a plan view of a behind-the-ear hearing aid including microphone placements, according to one embodiment of the present subject matter.
• the hearing assistance device 302 is a behind-the-ear (BTE) device, however, as stated above, the present subject matter can be applied to a variety of devices.
• BTE behind-the-ear
• the embodiment shown includes two directional microphones. In some embodiments, an omnidirectional microphone (not shown) is added to the combination.
• This configuration provides for the first axis to be at an angle from the second axis that is not 90 degrees.
• the symbol ⁇ is the amount of angle between the first and second axis.
• a zero degree or 180 degree embodiment features the directional microphone ports having parallel axes where the ports are not overlapping. For example, where the ports are side-by-side. Alternate zero degree or 180 degree embodiments include, but are not limited to, where the ports are along the same axis, but displaced in distance from each other.
• FIG. 4 shows a dual directional microphone system, according to one embodiment of the present subject matter.
• Directional microphone 402 is mounted on the housing of a hearing assistance device to receive sound from ports 1 and 2, and directional microphone 404 is mounted similarly to receive sound from ports 3 and 4.
• Microphone 402 produces a time varying signal having both amplitude and phase.
• Signal processor 406 applies amplitude A and phase ⁇ to the time varying signal to produce an output signal.
• the signal processor 406 is filtering.
• the filtering is performed in the frequency domain.
• the filtering is performed in the time domain.
• Microphone 404 produces a time varying signal having both amplitude and phase.
• Signal processor 408 applies amplitude C and phase ⁇ to the time varying signal to produce an output signal.
• the signal processor 408 is filtering, hi various embodiments, the filtering is performed in the frequency domain. In various embodiments, the filtering is performed in the time domain.
• the output signals are summed by summer 410. In various embodiments additional signal processing is performed on the summed signal.
• a receiver (loudspeaker) receives the resulting output and produces audio signals based on it.
• summer 410 derives the magnitude of each input signal individually and then does an addition of the resulting magnitudes. In one embodiment, summer 410 does a complex addition of the signals and then derives an overall magnitude of the complex sum.
• Different forms of directional microphones may be employed in various embodiments. For example, if directional microphones are used, such microphones can provide cardioid, supercardioid, dipole, or hypercardioid reception patterns for each individual directional microphone.
• Various embodiments include combinations of microphones having similar reception patterns.
• Various combinations include microphones having different reception patterns. Thus, various combinations of reception patterns can be accomplished, and the resulting summations of the reception fields can provide a distinctly different overall reception pattern for the hearing assistance device.
• FIG. 5 shows a microphone system including two directional microphones and an omnidirectional microphone, according to one embodiment of the present subject matter.
• Omnidirectional microphone 501 is mounted on the housing of a hearing assistance device to receive sound through a port.
• Omnidirectional microphone 501 produces a time varying signal having both amplitude and phase.
• Signal processor 503 applies amplitude B and phase a to the time varying signal to produce an output signal.
• the signal processor 503 is filtering, hi various embodiments, the filtering is performed in the frequency domain. In various embodiments, the filtering is performed in the time domain.
• the output is sent to summer 510.
• Directional microphone 502 and is mounted on the housing of a hearing assistance device to receive sound from ports 1 and 2, and directional microphone 504 is mounted similarly to receive sound from ports 3 and 4.
• Microphone 502 produces a time varying signal having both amplitude and phase.
• Signal processor 506 applies amplitude A and phase ⁇ to the time varying signal to produce an output signal.
• the signal processor 506 is filtering, hi various embodiments, the filtering is performed in the frequency domain. In various embodiments, the filtering is performed in the time domain.
• Microphone 504 produces a time varying signal having both amplitude and phase.
• Signal processor 508 applies amplitude C and phase ⁇ to the time varying signal to produce an output signal. In one embodiment, the signal processor 508 is filtering.
• the filtering is performed in the frequency domain
• the filtering is performed in the time domain.
• the output signals are summed by summer 510.
• additional signal processing is performed on the summed signal.
• a receiver (loudspeaker) receives the resulting output and produces audio signals based on it.
• summer 510 derives the magnitude of each input signal individually and then does an addition (or subtraction, which implies that the signal of one channel is multiplied by -1 before it is summed with the other channel) of the resulting magnitudes
• summer 510 does a complex addition of the signals and then derives an overall magnitude of the complex sum.
• directional microphones may be employed in various embodiments. For example, if directional microphones are used, such microphones can provide cardioid, supercardioid, dipole, or hypercardioid reception patterns for each individual directional microphone. Various embodiments include combinations of microphones having similar reception patterns. Various combinations include microphones having different reception patterns. Thus, various combinations of reception patterns can be accomplished, and the resulting summations of the reception fields can provide a distinctly different overall reception pattern for the hearing assistance device.
• processors 503, 506 and 508 and summer 510 can be implemented in hardware, software, or combinations thereof.
• a processor 512 performs all of the operations.
• Processor 512 in various embodiments, is a digital signal processor. In some embodiments, processor 512 is a microprocessor. Other embodiments exist which do not depart from the scope of the present teachings.
• FIG. 6 shows a microphone system including a directional microphone 602 and an omnidirectional microphone 601, according to one embodiment of the present subject matter.
• this configuration is achieved through signal processing by substantially reducing the gain, turning off, or ignoring the audio signal of a second directional microphone, such as the directional signal of a system according to FIG. 5.
• this configuration is achieved by dedicated microphones 602 and 601 and signal processor 606 and 603, respectively, feeding signals to summer 610.
• signal processors 603 and 606 and summer 610 can be implemented in hardware, software, or combinations thereof.
• a processor 612 performs all of the operations.
• Processor 612 in various embodiments, is a digital signal processor, hi some embodiments, processor 612 is a microprocessor. Other embodiments exist which do not depart from the scope of the present teachings.
• the placement of the omnidirectional microphone on the housing may vary.
• the omnidirectional microphone resides in the vicinity, or even shares one, of the directional ports. Different locations on the housing can employed without departing from the scope of the present subject matter.
• FIG. 7 is a polar plot showing one example of angular reception for a system operating according to one embodiment of the present subject matter and for a particular group of parameters for that system; namely, a cardioid directional microphone occupying ports 1 and 2 pointing towards 0° along axis 110, and a dipole directional microphone occupying ports 3 and 4 pointing along axis 105.
• the polar response is obtained by taking the magnitude of the complex sum (amplitude and phase) from each directional microphone.
• This polar response is frequency independent, assuming that the cardioid and dipole responses are frequency independent.
• the system is highly controllable and programmable.
• FIG. 8 is a polar plot showing one example of angular reception for a system operating according to one embodiment of the present subject matter and for a particular group of parameters for that system; namely, a cardioid directional microphone occupying ports 1 and 2 pointing towards 0° along axis 110, and a dipole directional microphone occupying ports 3 and 4 pointing along axis 105.
• the polar response is obtained by taking the difference between the cardioid magnitude and the dipole magnitude.
• This polar response is frequency independent, assuming that the cardioid and dipole responses are frequency independent.
• the system is highly controllable and programmable.
• the present system controls the reception pattern by adjusting A,B,C, ⁇ , a, ⁇ , ⁇ and ⁇ to produce a desired reception pattern.
• One way to set these parameters is to model the values using computer programs, such as MATLAB. Other programs and modeling may be performed without departing from the scope of the present subject matter.
• the port pairs can be separated by a number of various distances which are limited primarily by available space on the housing. For example, port pair distances 3mm to 26mm are possible in varying embodiments. Port spacings can vary between ports 1 and 2 as compared to the spacing of ports 3 and 4. Sound port shapes are shown as circular in the figures, but other shapes may be employed without departing from the scope of the present subject matter. For purposes of the discussion throughout this disclosure, port shapes are demonstrative only and can thus have various shapes and surface areas or can be covered with an acoustically appropriate material so that their features are not visible. It is understood that the present subject matter provides a great deal of flexibility and programmability. In various embodiments, an axis of the microphones is aligned with an intended direction of reception. In various embodiments, an axis of the microphones is offset from an intended direction of reception.
• the resulting signal from the foregoing embodiments is amplified and sent to a receiver (loudspeaker), which produces an audio version of the resulting signal.
• An additional processing step can occur before amplification if desired.
• the resulting signal can be transmitted using radio frequency energy.
• Other uses of the resulting signal are possible without departing from the scope of the present subject matter.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Neurosurgery (AREA)
• Otolaryngology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Circuit For Audible Band Transducer (AREA)
• Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

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• 2006
  • 2006-02-27 WO PCT/US2006/007058 patent/WO2006091971A1/fr not_active Ceased
  • 2006-02-27 CA CA002598534A patent/CA2598534A1/fr not_active Abandoned
  • 2006-02-27 DK DK06736381.2T patent/DK1851996T3/da active
  • 2006-02-27 EP EP06736381A patent/EP1851996B1/fr not_active Expired - Lifetime
  • 2006-02-27 AT AT06736381T patent/ATE524022T1/de not_active IP Right Cessation

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