Abstract: An infrared (IR) emitter having a broad emission pattern driven by a frequency-modulated (FM) carrier signal enables electronic communication between multiple talkers and multiple listeners. A narrow reception pattern on the listener's receiving unit combined with the inherent capture effect of FM coding provides each listener with the means of easily and naturally selecting one of many talkers from a group. A close microphone for the talking party and a close earphone for the listening party enables the system to assist conversation particularly in the case of noisy environments by improving the signal to noise ratio. A similar system of broad emission transmitters and narrow reception can be used in other systems, such as a teleconferencing unit in which users have transmitters and receivers and a teleconferencing unit has multiple receivers arranged to receive signals in multiple different sectors.

Abstract: An immersive hearing loss and auditory prostheses simulator allows a person who listens through the simulation system to experience an actual shift in his or her thresholds for detecting ambient sounds, in a way that is similar to the shift in thresholds experienced by a hearing-impaired person. The simulator shifts the listener's thresholds while also processing the input signals for suprathreshold stimulation. With a controlled degree of auditory threshold shift with loudness recruitment, a hearing loss simulator is made valid and flexible.

Abstract: Described is a miniature sound level dosimeter that is less expensive and more user-friendly than conventional sound level dosimeters. The dosimeter includes a frequency-weighting circuit, an envelope follower circuit, an analog-to-digital converter and a microcontroller. The frequency-weighting circuit applies a predetermined frequency-weighting, such as A-weighting, to an electrical signal indicative of the detected sound level to generate a frequency-weighted signal. An analog envelope signal is generated in response to the frequency-weighted signal and converted to a digital output signal. The microcontroller determines the sound dose in response to the digital output signal and a time interval.

Abstract: An immersive hearing loss and auditory prostheses simulator allows a person who listens through the simulation system to experience an actual shift in his or her thresholds for detecting ambient sounds, in a way that is similar to the shift in thresholds experienced by a hearing-impaired person. The simulator shifts the listener's thresholds while also processing the input signals for suprathreshold stimulation. With a controlled degree of auditory threshold shift with loudness recruitment, a hearing loss simulator is made valid and flexible.

Abstract: A hear-through hearing protective device includes at least two microphones, simulated-pinna filters, and a processing circuit. Elevation dependent directional cues are introduced by the processing performed by the simulated-pinna filters. Introduced directional cues are designed to allow the wearer to identify the source location of an acoustic signal.

Abstract: A hearing protector assembly has a muff and an ear-plug for hearing protection while allowing reception of audio communication. The muff has a receiver for audio signals, a modulation circuit, and a set of LEDs for transmitting the audio signal as a light signal. The ear-plug has a photovoltaic cell for receiving the light signals, a demodulator circuit, and a transducer for converting the received signal into an acoustic signal.

Abstract: A hearing aid has a directional receiving system with a more efficient direction into the patient's ear than away from the patient's ear.

Abstract: A speech recognition system includes an input subsystem consisting of two or more simple microphones, each with a relatively large acceptance angle. The simple microphones are positioned so that the acceptance angles overlap by a relatively small amount. If signals received by each of the simple microphones exceed predetermined thresholds, then a switch is closed to permit a speech recognition subsystem to receive a signal for processing. An additional simple microphone, with a relatively wide acceptance angle centered on the overlap of the other microphones may be used to receive the signals that are fed to the speech recognition subsystem for processing.

Abstract: A speech recognition system combines content analysis of a signal with directional analysis of the signal to calculate probable contents of the signal and the probability that the contents are as calculated. Content analysis can be combined with independent source direction analysis, consisting of the probable direction of the source and the probability that the source is as determined, to refine the content analysis. The direction analysis can affect either the calculation of the probable contents of the signal or the calculation of the probability that the contents are as calculated. The improved information obtained by combining the content analysis with directional analysis can be used to improve subsequent content analyses or directional analyses.

Abstract: A hearing aid has a plurality of microphones mounted in an array on a headband which extends from one ear over the top of the head to the other ear. The headband is flexible and adjustable in length. The headband has circuitry that can be switched among a directional monaural mode, a binaural mode, and a combination mode that provides both directionality and binaurally. Ganged controls are provided on the headband for both tone and volume. An external jack is provided on the headband to allow for the introduction of radio or recorded music from a personal stereo.

Abstract: A speech synthesizing method which uses glottal modelling to determine and transform ten or fewer high level parameters into thirty-nine low level parameters using mapping relations. These parameters are inputted to a speech synthesizer to enable speech to be synthesized more simply than with prior art systems that required 50 to 60 parameters to be inputted to represent any particular speech.

Abstract: Multiple single-frequency tones are presented simultaneously to a subject by each of two transducers for the purpose of testing hearing. One transducer is employed to present a plurality of f.sub.1 primaries and the other transducer a plurality of f.sub.2 primaries so as to make the ratio of f.sub.2 to f.sub.1 sufficient to produce evoked distortion products by the pair. Proper selection of the frequencies prevents numerous intermodulation products.

Abstract: Multiple single-frequency tones are presented simultaneously to a subject by each of two transducers for the purpose of testing hearing. One transducer is employed to present a plurality of f.sub.1 primaries and the other transducer a plurality of f.sub.2 primaries so as to make the ratio of f.sub.2 to f.sub.1 sufficient to produce evoked distortion products by the pair. Proper selection of the frequencies prevents numerous intermodulation products.

Abstract: An apparatus for and method of applying a selected range of high frequency acoustic energy to the apical end of the eardrum of an ear canal at a predetermined, substantially absolute sound pressure level at any frequency in the range of interest. The selected range of frequencies is generated at a location remote from the ear canal and the sound pressure level of each frequency is varied at the time of generation in accordance with a calibration function to ensure the frequencies reaching the apical end of the eardrum are at the predetermined sound pressure level.The calibration function is calculated by transmitting an acoustic pulse of broad frequency spectrum into the ear canal, measuring the sound pressure of the transmitted acoustic pulse and reflection thereof adjacent the entrance of the ear canal, and removing from the spectrum of the measured sound pressure the destructive interference effects between the transmitted and reflected acoustic pulses.