Biomedical subjects

J J Dempsey

Publications and source records attributed to J J Dempsey.

4 recordsLinked to original sources

PubMed1992

Computer-assisted tracking simulation (CATS).

The tracking technique involves a sender reading consecutive segments from a story and a receiver attempting to repeat each segment verbatim. The reliability and validity of the tracking procedure have been criticized based upon uncontrolled variables such as sender, receiver, and text characteristics. To address these problems, a computer-assisted interactive tracking simulation (CATS) system has been developed in which story segments are presented to the receiver via a video laser disc system and repair strategies are implemented through a computer program.

Communication Devices for People with Disabilities↗

PubMed1991

An evaluation of two signal-processing hearing aids.

Various forms of signal processing are used in modern ASP hearing aids. The present study investigated the relationship between sentence recognition ability and two types of signal processing used in commercially available hearing aids. Results indicated a significant improvement in sentence recognition ability employing an instrument with adaptive compression (variable release time) versus an instrument with an adaptive high-pass filter with short attack and release times. Data were obtained for a single-talker competing message at several message-to-competition ratios. The adaptive compression system may prove to be beneficial to hearing-impaired listeners in certain background noise environments.

Aged↗

PubMed1990

Bone vibrator placement and the cancellation technique.

An issue in the measurement of bone conduction sensitivity is the placement of the bone vibrator. The effect of bone vibrator position on the amplitude and phase of the received signal was investigated using a cancellation technique. This technique involves cancelling the signal delivered by the bone vibrator with a signal delivered acoustically via an earphone. At cancellation, the acoustic signal is equal in amplitude but opposite in phase to the bone-conducted signal. Results showed that the amplitude of the received signal did not vary significantly with bone vibrator position close to the center of the forehead whereas the phase of the received signal was critically dependent on bone vibrator position. Substantial intersubject differences were observed in the variation of phase with bone vibrator position. The precision of measurement using the cancellation technique was found to be high.

Acoustics↗

PubMed1990

The occlusion effect created by custom canal hearing aids.

There has recently been a dramatic increase in the demand for custom canal hearing aids. One of the significant limitations sometimes created by these instruments is the increased sensitivity to bone-conducted stimuli known as the occlusion effect. A large occlusion effect is often cited as the reason for rejection of these devices. This investigation tested a method of measuring the occlusion effect through bone-conducted speech reception thresholds (SRTs). The results indicated that the bone conducted SRT procedure is sensitive enough to differentiate between the occlusion effect created by shell earmolds versus canal hearing aids.

Bone Conduction↗