Extended high-frequency pure-tone thresholds predict speech-in-speech recognition even when extended high-frequency speech cues are absent

Abstract

Recent work has demonstrated that extended high-frequency (EHF; >8 kHz) hearing is valuable for speech-in-noise recognition. These findings contradict the broadly accepted “speech bandwidth” that has historically been limited to below 8 kHz. Several studies also indicate that EHF pure-tone thresholds predict speech-in-noise performance. One question that has arisen is whether the association that has been observed between EHF pure-tone thresholds and speech-in-noise recognition is causal—that loss of audibility of EHF cues in speech degrades speech-in-noise recognition. Indeed, this effect has been demonstrated using low-pass filtering, but whether elevated EHF thresholds would produce a similar effect is not certain. Another possibility is that EHF thresholds are a marker for subclinical dysfunction at lower frequencies that degrades speech recognition. These two possibilities are not mutually exclusive (nor exhaustive) and each could contribute to the observed relationship. Here we present a reanalysis of previous data collected in our lab, the results of which suggest that 16-kHz pure-tone thresholds are consistent predictors of speech-in-speech recognition, regardless of whether EHF cues are present in the speech signal. These findings suggest elevated EHF thresholds may indicate subclinical auditory dysfunction impairing speech-in-speech recognition.