Hearing-normal listeners give far more consistent loudspeaker quality ratings.

Evidence

The first clear evidence of the issue with hearing came in 1982 during an extensive set of loudspeaker evaluations conducted for the Canadian Broadcasting Corporation (CBC), in which many of the participants were audio professionals: recording engineers, producers, musicians. Unfortunately, for them, hearing loss is an occupational hazard. During analysis of the data, it was clear that some listeners delivered remarkably consistent overall sound-quality ratings (then called fidelity ratings, reported on a scale ranging 0 to 10) over numerous repeated presentations of the same loudspeaker. Others were less good, and still others were extremely variable, liking a product in the morning and disliking it in the afternoon, and each time writing a clear explanation why. The cause was not hard to find. Separating listeners according to their audiometric performances, it was apparent that those listeners with hearing levels closest to the norm (0 dB) had the smallest variations in their judgments. Figure 10.5 shows examples of the results. Surprisingly, it was not the high-frequency hearing level that correlated with the judgment variability but that at frequencies at or below 1 kHz, people who also have high-frequency loss. Bech (1989) confirmed the trend. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1065

Categorization

• QUESTION: Why would low-frequency hearing thresholds specifically predict judgment variability rather than high-frequency loss? The broadband explanation suggested deserves follow-up.
• SEED: Angle: hearing loss as occupational hazard in audio professions — the people who judge sound for a living are systematically losing the ability to do so consistently.