Training in ABR

The development of Fsp and Fmp

Intermediate
10 mins
Reading
07 February 2022

Summary of: Elberling, C., & Don, M. (1987). Threshold characteristics of the human auditory brain stem responseThe Journal of the Acoustical Society of America81(1), 115–121. https://doi.org/10.1121/1.395019

This paper describes and analyzes ABRs recorded from ten normal-hearing subjects in response to 100 μs clicks from a TDH 49 earphone at a rate of 48 pps and at levels randomly varied in 2-dB steps between 34 and 52 dB p.e.SPL (approximately 0 - 20 dB nHL). At each level, 10 000 sweeps are averaged using weighted averaging. A running estimate of the signal-to-noise ratio (SNR), FSP, is used to detect the presences of the ABR. The median threshold is found at 38 dB p.e.SPL (approximately 5 dB nHL). The mean averaged background noise level is 11.3 nVrms, and the ""true"" ABR amplitude function crosses this value at 35.5 dB p.e.SPL (2 – 3 dB nHL), which indicates the level where the SNR = 1. By extrapolation it is found that the ABR amplitude becomes zero at 32 dB p.e.SPL. The perceptual thresholds of the click are estimated by means of a modified block up-down procedure and the median value is found at 33 dB p.e.SPL. The slope of the amplitude function and the magnitude of the averaged background noise are the two factors responsible for the ABR threshold sensitivity which thus depends on both physiological and technical parameters. Therefore, these have to be considered together with the method of detection when the ABR is used as an indicator of the hearing sensitivity.

Related course: Beyond the Basics: Threshold ABR

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