Abstract: A directional microphone assembly suitable for subsurface mounting. A directional pickup pattern is developed from the outputs of a plurality of omnidirectional microphone elements mounted in an assembly behind a surface such that their acoustic excitation comes from the opposite side of the surface through small openings in the surface. The openings may have varying dimensions and may be covered with acoustically semi-transparent material without significantly degrading the assembly frequency response or polar pattern. Precautions are taken to ensure design robustness considering practical microphone element characteristics and potential high levels of low-frequency excitation.

Abstract: A hearing improvement device using a multi-coil coupling system and methods for operating such a device are disclosed. An embodiment of the present invention may use an array microphone to provide highly directional reception. The received audio signal may be filtered, amplified, and converted into a magnetic field for coupling to the telecoil in a conventional hearing aid. Multiple transmit inductors may be used to effectively couple to both in-the-ear and behind-the-ear type hearing aids, and an additional embodiment is disclosed which may be used with an earphone, for users not requiring a hearing aid.

Abstract: Disclosed herein is an adaptor for use with a mobile cellular telephone, a combination cellphone/adaptor, and a method of using a hearing aid with a cellphone employing an adaptor according to an embodiment of the present invention. The adaptor may include a microphone, a battery, an inductor, and electronic circuitry disposed on a circuit board. The microphone may be positioned generally over receiver acoustic openings of the cellphone. The adaptor may be adapted to amplify a microphone signal to drive an inductor. The inductor may be located at an end of the adaptor. The inductor field may be concentrated in a region where a magnetic noise field associated with cellphone circuitry may be much lower.

Abstract: A hearing aid system for selecting one of two audio sources is disclosed. The hearing aid system comprises hearing aid circuitry, such as, for example, a hearing aid amplifier and speaker, as well as a primary source for audio, such as, for example, a hearing aid microphone. The hearing aid system also comprises a secondary source for audio, such as, for example, a directional microphone worn or otherwise supported by a person speaking or by the hearing aid user, as well as detection and switch circuitry to select which of the primary and secondary audio sources should be directed to the hearing aid circuitry. In operation, the detection and switch circuitry receives a signal transmission (preferably wireless) from the secondary audio source and determines whether the signal received is desirable. If the signal transmission is desirable, the circuitry selects that signal for coupling with the hearing aid circuitry.

Abstract: A hearing improvement device using a multi-coil coupling system and methods for operating such a device are disclosed. An embodiment of the present invention may use an array microphone to provide highly directional reception. The received audio signal may be filtered, amplified, and converted into a magnetic field for coupling to the telecoil in a conventional hearing aid. Multiple transmit inductors may be used to effectively couple to both in-the-ear and behind-the-ear type hearing aids, and an additional embodiment is disclosed which may be used with an earphone, for users not requiring a hearing aid.

Abstract: The present invention relates to a motor vehicle mounted directional microphone assembly for use in hands-free cellular telecommunications. The microphone assembly is comprised of a case and a removable directional microphone module. The case is adapted to mount and lock the module in a plurality of different orientations, thereby enabling the assembly to accommodate various mounting arrangements within the vehicle. The module is releasable, however, from its locked position to permit re-orientation of the microphone with respect to the case, if desired. The module is also completely removable from the case to permit mounting of the module within the vehicle in mounting arrangements independent of the case.

Abstract: A hearing aid system for selecting one of two audio sources is disclosed. The hearing aid system comprises hearing aid circuitry, such as, for example, a hearing aid amplifier and speaker, as well as a primary source for audio, such as, for example, a hearing aid microphone. The hearing aid system also comprises a secondary source for audio, such as, for example, a directional microphone worn or otherwise supported by a person speaking or by the hearing aid user, as well as detection and switch circuitry to select which of the primary and secondary audio sources should be directed to the hearing aid circuitry. In operation, the detection and switch circuitry receives a signal transmission (preferably wireless) from the secondary audio source and determines whether the signal received is desirable. If the signal transmission is desirable, the circuitry selects that signal for coupling with the hearing aid circuitry.

Abstract: An automatic microphone control system particularly suited to controlling a small, predetermined number of microphones. A representation of the level of a microphone signal is compared individually to the level representations of each of the other microphones to determine if the microphone should receive a gating trigger. If the microphone level compares favorably to each of the other microphones, and a noise adaptive threshold comparison criterion is also satisfied, then the microphone receives a gating trigger. This triggers a gate ON action for the microphone, which is held at least 0.4 seconds by a one-shot and also locked ON unless a gate ON action is initiated by any other microphone. The circuitry for a two-microphone system particularly suited to a lectern application is powerable by a conventional phantom-powering balanced microphone preamplifier input.

Abstract: An improved automatic microphone actuation control system. The system exhibits a high degree of resistance to inappropriate secondary microphone actuation by reverberant sound, even when two or more microphones in a system are operated at significantly different electroacoustic gains. The system further exhibits improved actuation sensitivity to local conference room speech occurring simultaneously with teleconference loudspeaker sound which is strongly coupled acoustically to the microphones. A Reverb Inhibit Bus, which is the maximum of a reduced level speaker inhibit signal and substantially attenuated versions of the DC microphone signal level representations, drives the microphone channels' noise adapting threshold circuitry. Such circuitry is driven in a manner to inhibit microphone actuation for teleconference loudspeaker sound reverberation and reverberation of local conference room speech which has already actuated a microphone.

Abstract: An echo reduction circuit that may be used to reduce the returned echo in communication links with signficant delay. By making effective use of the echo-masking effect of near-simultaneous desired speech energy and the redundancy present in normal speech, the circuit makes possible wide bandwidth, non-choppy, perceived distortion-free, and perceived echo-free teleconferencing. The circuit performs a rapid time constant, semi-waveform-following partial attenuation of a preemphasized version of the returning transmit signal proportional to a calculation of the likely strength of the returned echo in relation to the strength of the local speech.

Abstract: An adaptive delta modulation circuit having an analog adaptation circuit and an integrator circuit. The adaptation circuit exponentially converts a voltage which is proportional to the average of a time duration of an overload control signal to an adaptation current which is averaged and converted to an adaptation voltage. An integrator circuit includes a sole switch which shorts to ground a circuit point for generating an analog signal formed of line segments; each segment has a slope magnitude controllable by the adaptation voltage.

Abstract: A teleconferencing system for connection to telephone lines or other communication links. Directionally gated microphones receive local speech for audio send signal transmission to the far end on the telephone line, and audio receive signals from the far end are output locally via a loudspeaker. The outgoing send signals and incoming receive signals are automatically suppressed in accordance with user and setup controls (volume and suppression) and in accordance with the strength of the incoming receive signal. When the system is in a send mode, the receive signals are suppressed to a lower audible level; when the system is in a receive mode, the send signals are suppressed. The mode of the system is switched during conversation. When simultaneous talking (speech from both ends) occurs, priority is given to the interrupting party.

Abstract: A system for receiving a plurality of audio input signals encoded with sound directions drives a plurality of loudspeakers which are physically arranged to generate apparent sound images in relation to encoded sound directions. The encoded input signals are analyzed for determining whether one encoded sound direction exceeds a predominance threshold with respect to other encoded sound directions. Logic control signals are generated for indicating directionality of predominant sound directions. In response to generated logic signals, the directional stability of the apparent sound images is enhanced.

Abstract: A microphone and loudspeaker arrangement for use in a teleconference system, wherein a plurality of microphones are held in a fixed relationship to a loudspeaker. The microphones are independently gated ON in response to (1) speech picked up by the microphone, (2) a loudspeaker signal driving the loudspeaker and (3) an electrical signal related to the microphone signals of the other associated microphones. A noise adapting threshold circuit generates a voltage level representative of background noise which is compared with the microphone signal of a respective microphone for determining whether the microphone is receiving speech. A decisional circuitry monitors the microphone signal of the associated microphone with respect to a MAX bus which carries microphone signals representative of the level of microphone signals at the other microphones. The decisional circuitry generates a signal indicating that the associated microphone is the first loudest microphone signal.