On the Etiology of Listening Difficulties in Noise Despite Clinically Normal Audiograms

Abstract

Many people with difficulties following conversations in noisy settings have “clinically normal” audiograms, that is, tone thresholds better than 20 dB HL from 0.1 to 8 kHz. This review summarizes the possible causes of such difficulties, and examines established as well as promising new psychoacoustic and electrophysiologic approaches to differentiate between them. Deficits at the level of the auditory periphery are possible even if thresholds remain around 0 dB HL, and become probable when they reach 10 to 20 dB HL. Extending the audiogram beyond 8 kHz can identify early signs of noise-induced trauma to the vulnerable basal turn of the cochlea, and might point to “hidden” losses at lower frequencies that could compromise speech reception in noise. Listening difficulties can also be a consequence of impaired central auditory processing, resulting from lesions affecting the auditory brainstem or cortex, or from abnormal patterns of sound input during developmental sensitive periods and even in adulthood. Such auditory processing disorders should be distinguished from (cognitive) linguistic deficits, and from problems with attention or working memory that may not be specific to the auditory modality. Improved diagnosis of the causes of listening difficulties in noise should lead to better treatment outcomes, by optimizing auditory training procedures to the specific deficits of individual patients, for example.

‘Normal’ hearing thresholds and fundamental auditory grouping processes predict difficulties with speech-in-noise perception

“…We infer from these results that speech-in-noise difficulties may arise from changes to the auditory periphery that are related to, but which precede, clinically relevant changes in thresholds. Although audiometric thresholds at frequencies higher than 8 kHz have been proposed to contribute to speech perception in challenging listening environments (see Pienkowski, 2016), these frequencies are not routinely measured in clinical practice. That we found correlations with 4-8 kHz audiometric thresholds suggests that speech-in-noise difficulties could be predicted based on audiometric thresholds that are already part of routine clinical assessment.…”

“…Despite this, we also sought to examine whether sub-clinical variability in audiometric thresholds, which index aspects of peripheral processing, contain information relevant for predicting speech-innoise perception. This follows from the idea that speech-in-noise difficulties may arise from changes to the auditory periphery that are related to, but which precede, clinically relevant changes in thresholds (see Pienkowski, 2016). Given that high-frequency thresholds are suspected to deteriorate first in age-related hearing loss (Wiley et al, 2008), we tested thresholds at 4-8 kHz.…”

Minimal and mild hearing loss in children: Association with auditory perception, cognition, and communication problems

“…The same is true for the terms 'minimal' and, to a lesser extent, 'mild' hearing loss, with no consensus on definitions. It seems certain that any specific limit will be a simplification in any case, since loss of auditory function (hearing impairment) is individually and, across a population, continuously variable, and includes impairments that are not well predicted by pure tone detection threshold (Pienkowski, 2017;Le Prell, 2019).…”

“…Comparison with published reports (Beahan et al 2012) using conventionally recorded audiometric data in children over an age range including that used here showed a comparable level of test-retest reliability (~ 5 dB), and its modest (~ 2 dB) improvement with age between 6 -11 y.o. Audiometric thresholds are not necessarily a good predictor of speech perception, particularly in acoustically challenging environments (Pienkowski 2017;Le Prell 2019). This may be due to the unique auditory requirements of processing speech and to individual variation in the additional cognitive load of recognizing speech-in-noise, compared with the detection of tones-in-quiet.…”

“…The exclusive or even primary use of conventional audiometry to index hearing impairment is currently being challenged by several emerging discoveries and constructs including unexplained difficulty hearing speech-innoise (Pienkowski 2017), 'hidden' hearing loss (e.g. cochlear synaptopathy; Liberman 2015), 'extended frequency' hearing loss (tones > 8 kHz; Monson et al 2014), and 'hearing critical tasks' (Dubno 2018;Soli et al 2018).…”