Characterizing Suprathreshold Auditory Function: A Comparison of 22 Direct and Derived Auditory Measures

A substantial proportion of the population has clinically normal hearing thresholds yet experiences difficulty understanding speech in background noise. Existing hearing models explain these difficulties using a limited number of physiological and signal-processing mechanisms, implying that relationships among psychoacoustic measures may reflect shared underlying processes. However, these relationships have rarely been examined comprehensively within the same participants. Here we quantified associations among psychoacoustic measures using linear regression and principal component analysis. Speech-in-noise, tone-in-noise in different noise types, and loudness growth functions were obtained and analyzed in monaural and binaural listening conditions in 52 volunteers (aged 20-80 years) with age-typical or mild hearing loss (PTA4 < 32.5 dB HL). Linear regression analyses identified direct psychoacoustic measures - particularly interaurally antiphasic tone-in-noise (N0Sπ) thresholds - as robust indicators of suprathreshold hearing function. Although N0Sπ showed only a moderate association with the corresponding diotic thresholds (N0S0), it was more strongly associated with poorer-ear speech-in-noise thresholds (r = 0.60) than the corresponding 500-Hz audiometric threshold (r = 0.35), suggesting that this relationship was not driven by audibility alone. Exploratory principal component analysis further showed that N0Sπ thresholds contributed to multiple auditory dimensions associated with speech-in-noise variability. In contrast, derived measures such as binaural masking level difference or auditory filter bandwidth showed weaker and less consistent associations. Overall, the results indicate that selected direct psychoacoustic measures may provide a more robust characterization of suprathreshold auditory function than derived measures.