Y-linked mutations are rare genetic changes on the Y chromosome that can lead to isolated or syndromic hearing disorders in men. As 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 transduction. Diagnostically, targeted sequencing of the Y chromosome is carried out if other inheritance patterns have been ruled out. Genetic counseling clarifies carrier status and risk in male offspring.

The Y-frequency shift describes the psychophysical phenomenon that the perceived pitch of very loud sounds is slightly shifted into higher frequency ranges. It occurs because cochlear non-linearities and the activity of the outer hair cells change the effective tonotopy on the basilar membrane. Measurements of the shift are made using comparison tones and pitch-matching methods. This effect is relevant for the fine-tuning of hearing aids, as amplification profiles at high levels can slightly change the pitch. In research, the investigation of the Y-displacement helps to better understand cochlear compression mechanisms.

The Y-value is a specific figure in the audiogram that quantifies the ratio of speech intelligibility at different signal-to-noise ratios. It is often expressed as a 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 noise. Audiologists use the Y value to specifically optimize hearing aid compression and noise reduction. It supplements classic threshold indicators with a functional assessment of the fitting situation.