Blind and experienced musicians are more precise in perceiving pitch

Scientists compared two aspects of auditory perception: tone detection and pitch discrimination. These tasks rely on different mechanisms: tone detection primarily depends on the functioning of the cochlea in the inner ear, while pitch discrimination depends on cortical processing in the brain. The experiment involved people with intact vision, people who became blind at an early age, and musicians with varying levels of training.

The results showed that there were no differences between the groups in terms of tone detection ability: both sighted and blind participants performed the task with equal accuracy. However, when it comes to distinguishing the pitch of a sound, people with congenital or early‑acquired blindness turned out to be noticeably more accurate than sighted people.

To understand what accounts for this advantage, researchers applied a mathematical model and discovered an important nuance: in people who lost their sight in childhood, the brain shows less random variability in responses to the same sound from time to time. This variability is called “internal noise.” Simply put, their nervous system processes the sound signal more stably and reliably.

Then they checked whether this phenomenon is unique to blindness or whether similar changes can occur due to the active use of hearing. To this end, the experts included people with different levels of musical training in the study. It turned out that experienced musicians also have a reduced level of internal noise, and this is what improves their ability to distinguish the pitch of sounds. Moreover, the effect depended on the level of training: the more musical experience a person had, the more consistently the brain responded to the same stimuli.

According to the authors, the main conclusion of the study is that the improvement in hearing in people who became blind early in life is selective in nature. The widespread belief that hearing improves after the loss of vision is not supported, as the advantages are evident precisely in tasks where reliable information processing in the brain is important, rather than in the functioning of the peripheral auditory system. The similarity of the results in the blind and in musicians suggests that some of these improvements are the result of experience: the brain learns to use auditory information more effectively.