Analysis of the analog circuit's SNR in the selection of ADC bit resolution.
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Audiometry↗
Biomedical subjects
T A Hamill
Publications and source records attributed to T A Hamill.
Threshold estimation using the "chained stimuli" auditory brain stem response technique.
The chained stimuli ABR method, which allows acquisition of data for a seven-point latency-intensity function for both ears in approximately 35 min, is described. Testing of 22 ears with a simulated conductive loss, and 20 ears with sensorineural impairment, indicates that the chained stimuli method provides equivalent threshold estimates to that obtained with the conventional ABR measurement technique.
Acoustic Impedance Tests↗
Frequency response differences of four gain-equalized hearing aid prescription formulae.
The relative differences between the NAL, Berger, Lybarger und POGO hearing aid prescriptions were evaluated using 8 hypothetical audiograms and 81 actual hearing loss cases. The gains of the prescriptions were equalized, making the prescriptions maximally similar, as would presumably occur when the aids are worn. Statistically significant differences in the frequency responses of the prescriptions were found, with up to 17 dB gain difference observed; however, the gain differences at any given frequency were generally less than 8 dB. Sharply sloping hearing losses had the greatest differences between prescriptions. The NAL and Berger prescriptions were most disparate, while POGO and Lybarger were most similar. As large differences in prescribed gain are rare, research into the relevance of such small differences in frequency response is advocated as a precursor to study of the optimal prescription formula.
Ear↗
Rapid threshold estimation using the "chained-stimuli" technique for auditory brain stem response measurement.
The "chained-stimuli" technique for rapid auditory brain stem response (ABR) threshold estimation involves lengthening the averaging time window and presenting a series ("chain") of click stimuli. Each stimulus chain contains, in addition to a silent interval, click stimuli of 10, 20, 30, 40, 50, 60, and 70 dB nHL that are separated by 10 msec intervals. Using this method, the single averaged response to the chained-stimulus contains up to seven individual ABRs. The responses elicited by each level of click stimulus within the chain can be analyzed separately. In this study, chained-stimuli ABR threshold estimations for normal hearers were essentially equivalent to those obtained using an automated conventional ABR method. The data for a seven point latency-intensity function using the chained-stimuli technique were obtained in a mean time of only 8 min per ear.
Acoustic Stimulation↗