Temporal Processing Deficits
Helfer and Vargo (2009) noted that, "It is tantalizing to consider that temporal processing may be an underlying cause of problems understanding speech in competing speech." More recently, Fullgrabe et al (2015) investigated the impact of aging with regard to the ability of people with normal audiograms to understand speech, and they sought to determine the impact of cognition and auditory temporal processing on speech understanding. They reported that even in the absence of peripheral hearing loss (as measured by the audiogram) speech-in-noise (SiN) identification declines with age.
Beck (2015) reported that “for many children and adults with normal hearing, invisible hearing loss may be (and often is) present in tandem with normal audiograms.” Specifically, he reported, that maximal listening requires cognitive ability including attention, working memory, listening effort and “the maintenance of natural acoustic cues such as interaural loudness differences (ILDs) and interaural timing differences (ITDs) to facilitate binaural summation and binaural squelch." Beck stated that “a simple audiogram cannot document, estimate, reflect, or quantify speech-in-noise problems, neural or auditory processing difficulties, perceived distortions (loudness, spectral, or timing and more), attentional difficulties, etc.”
Grose et al (2015) address the emergence of temporal processing deficits that appear in middle age (40 to 60 years). They report temporal fine structure (TFS) and the temporal envelope of the acoustic waveform are of significant importance when evaluating temporal processing deficits in middle age. TFS coding is likely to impact segregation and spatial identity of competing sounds, including tracking “target voices” in competing speech environments. Grose et al note that there exists evidence that “deficits in temporal envelope processing” can be detected early in the aging process. They conclude that “a disassociation between suprathreshold hearing difficulty and audiometric sensitivity is not surprising.” Specifically, they note that the "deficits in both temporal envelope and temporal fine structure processing are evident during middle age while audiometric (often) hearing sensitivity remains normal."
For More Information, References, and Recommendations
Beck DL. (2015) Invisible Hearing Loss American Academy of Audiology Web site.
Fullgrabe C, Moore BCJ, Stone MA. (2015) Age-group Differences in Speech Identification Despite Matched Audiometrically Normal Hearing: Contributions from Auditory Temporal Processing and Cognition. Frontiers.
Grose GH, Mamo SK, Buss E, Hall JW. (2015) Temporal Processing Deficits in Middle Age. American Journal of Audiology 24:91.
Helfer KS, Vargo M. (2009) Speech Recognition and Temporal Processing in Middle-Aged Women. Journal of the American Academy of Audiology 20(4):264-271.