Development of the Hearing In Noise Test for the measurement of speech reception thresholds in quiet and in noise

TLDR

The study developed a large set of uniformly long, natural‑speech sentence materials for measuring sentence speech reception thresholds (sSRTs). These materials were calibrated to equal intelligibility in spectrally matched noise and organized into 25 phonemically balanced lists of ten sentences for adaptive sSRT measurement. The test yielded 95 % confidence intervals of ±2.98 dB in quiet and ±2.41 dB in noise, mean sSRTs of 23.91 dB(A) in quiet and 69.08 dB(A) (−2.92 dB SNR) in 72 dB(A) noise, and retained reliability until bandwidth dropped below 2.5 kHz, confirming its statistical reliability and practical efficiency.

Abstract

A large set of sentence materials, chosen for their uniformity in length and representation of natural speech, has been developed for the measurement of sentence speech reception thresholds (sSRTs). The mean-squared level of each digitally recorded sentence was adjusted to equate intelligibility when presented in spectrally matched noise to normal-hearing listeners. These materials were cast into 25 phonemically balanced lists of ten sentences for adaptive measurement of sentence sSRTs. The 95% confidence interval for these measurements is ±2.98 dB for sSRTs in quiet and ±2.41 dB for sSRTs in noise, as defined by the variability of repeated measures with different lists. Average sSRTs in quiet were 23.91 dB(A). Average sSRTs in 72 dB(A) noise were 69.08 dB(A), or −2.92 dB signal/noise ratio. Low-pass filtering increased sSRTs slightly in quiet and noise as the 4- and 8-kHz octave bands were eliminated. Much larger increases in SRT occurred when the 2-kHz octave band was eliminated, and bandwidth dropped below 2.5 kHz. Reliability was not degraded substantially until bandwidth dropped below 2.5 kHz. The statistical reliability and efficiency of the test suit it to practical applications in which measures of speech intelligibility are required.