Michael P. O'connell

Electronic filters, hearing aids and methods

An electronic filter for an electroacoustic system. The system has a microphone for generating an electrical output from external sounds and an electrically driven transducer for emitting sound. Some of the sound emitted by the transducer returns to the microphone means to add a feedback contribution to its electical output. The electronic filter includes a first circuit for electronic processing of the electrical output of the microphone to produce a filtered signal. An adaptive filter, interconnected with the first circuit, performs electronic processing of the filtered signal to produce an adaptive output to the first circuit to substantially offset the feedback contribution in the electrical output of the microphone, and the adaptive filter includes means for adapting only in response to polarities of signals supplied to and from the first circuit. Other electronic filters for hearing aids, public address systems and other electroacoustic systems, as well as such systems, and methods of operating them are also disclosed.

Implementation of a Microprocessor-Based Tactile Hearing Prosthesis

A microprocessor-based tactile vocoder is described that offers important advantages over its analog counterpart. Digital implementation provides more flexibility and precision. The system simulates, in real-time, the characteristics of a 16-channel tactile vocoder developed at Queens University in Kingston, Ont., Canada and is intended for use with a linear array of 16 miniature vibrators. Design considerations of the circuit logic, program structure, and algorithms used to implement the vocoder and the performance characteristics such as the dynamic range and noise of the various algorithms are discussed. The overall system has a noise level less than ¿60 dB re the maximum input and the bandwidth is 7.5 kHz. The system will first be used in the laboratory and in the classroom with two microphones and two tactile displays. Future plans call for the design to be adapted to lower power devices, when they become available, to achieve a single-display, wearable version that can be evaluated under natural conditions of acoustic signal and noise.

Evaluation of a digital hearing aid and fitting system

The results of the evaluation of a body‐worn, programmable digital hearing aid in short‐term field studies of 3 days to 3 weeks on six hearing‐impaired subjects will be presented. The hearing aid was programmed to implement a four‐channel instantaneous compression hearing aid model. Frequency selective channel gains and maximum power output settings of the hearing aid were controlled by a computer‐based, hearing‐aid evaluation system. This system integrated real‐ear measurements and hearing aid control capabilities to achieve several different real‐ear frequency/gain characteristics for each subject. The desired real‐ear gains were calculated based on a prescriptive fitting method applied to hearing threshold and most comfortable listening levels. The performance of the device with the user‐preferred real‐ear gain curve was evaluated using speech intelligibility testing and HAPI questionnaires completed after using the digital hearing aid. The speech intelligibility testing consisted of a computer automat...

A wearable multichannel vibrotactile aid for the deaf

It has been determined that hearing‐impaired and normal‐hearing subjects can learn to identify words using only a tactile vocoder [Brooks and Frost, J. Acoust. Soc. Am. 74, 34–39 (1983)]. Further studies have shown that certain multichannel tactile vocoders provide significant help in understanding connected discourse as an aid in lipreading [Weisenberger and Miller, J. Acoust. Soc. Am. 82, 906–916 (1987)]. A review of this research is given in a companion paper (Weisenberger, Abstract J1). Motivated by these results, a wearable, 16‐channel vibrotactile aid has been developed that can be used by hearing‐impaired subjects during normal daily activities. The system consists of a body‐worn processor that is 3.5 × 5.5 × 1.5 in. in size and a vibrator array worn on the arm. In addition to the 16‐channel vocoder algorithm, the microprocessor‐based system can be programmed to implement other processing algorithms using the existing hardware. The system and its performance characteristics will be described. [Work supported in part by NIH.]It has been determined that hearing‐impaired and normal‐hearing subjects can learn to identify words using only a tactile vocoder [Brooks and Frost, J. Acoust. Soc. Am. 74, 34–39 (1983)]. Further studies have shown that certain multichannel tactile vocoders provide significant help in understanding connected discourse as an aid in lipreading [Weisenberger and Miller, J. Acoust. Soc. Am. 82, 906–916 (1987)]. A review of this research is given in a companion paper (Weisenberger, Abstract J1). Motivated by these results, a wearable, 16‐channel vibrotactile aid has been developed that can be used by hearing‐impaired subjects during normal daily activities. The system consists of a body‐worn processor that is 3.5 × 5.5 × 1.5 in. in size and a vibrator array worn on the arm. In addition to the 16‐channel vocoder algorithm, the microprocessor‐based system can be programmed to implement other processing algorithms using the existing hardware. The system and its performance characteristics will be described. [Work...