Y-chromosomal mutations are rare genetic changes on the Y chromosome that can lead to isolated or syndromic hearing disorders in men. Since women do not have a Y chromosome, they are not affected by such mutations, whereas men usually show a pronounced phenotype. Mutations often affect genes involved in the development of hair cells or cochlear signal transmission. Targeted sequencing of the Y chromosome is performed for diagnostic purposes when other inheritance patterns have been ruled out. Genetic counseling clarifies carrier status and risk for male offspring.

Y-frequency shift refers to the psychophysical phenomenon whereby very loud sounds are perceived as having a slightly higher pitch. It occurs because cochlear nonlinearities and the activity of the outer hair cells alter the effective tonotopy on the basilar membrane. Measurements of the shift are made using comparison tones and pitch matching procedures. This effect is relevant for the fine tuning of hearing aids, as amplification profiles at high levels can slightly alter the pitch. In research, the study of Y-shift helps to better understand cochlear compression mechanisms.

The Y value is a specific indicator in the audiogram that quantifies the ratio of speech intelligibility at different signal-to-noise ratios. It is often expressed as the percentage difference between recognition rates at +5 dB and +10 dB SNR. A high Y value indicates robust speech intelligibility even in noisy environments, while a low value indicates difficulties in noisy environments. Audiologists use the Y value to optimize hearing aid compression and noise reduction. It supplements classic threshold indicators with a functional assessment of the hearing aid situation.