Lifelong blindness enhances brain processing for better pitch discrimination

Are people who have been blind for most of their lives better at hearing than sighted individuals? New in JNeurosci, Woon Ju Park, from Georgia Institute of Technology, and colleagues, broached this question by comparing tone detection and pitch discrimination in people with and without sight. The researchers assessed these aspects of hearing because they have different mechanisms: Tone detection involves the cochlea of the ear, and pitch discrimination involves cortical processing in the brain. 

People with and without vision detected tones accurately, but those with lifelong blindness were better at discriminating between pitches than individuals with intact vision. Probing this difference further by using a mathematical model, the researchers discovered that people who became blind early in life showed less random variability in how their brains responded to the same pitch from one moment to the next, a phenomenon referred to as internal noise. 

Park et al. then wondered whether this effect is specific to vision loss, or if other groups of people who engage acute listening skills have similar reductions in internal noise. The researchers selected people with different levels of music training and compared their hearing ability using the same measures. Similar to people without sight, those with more musical experience had less internal noise that enhanced their ability to discriminate between pitches. 

I think one of the main implications from this work is that enhanced hearing in individuals who became blind early in life is selective. Blindness is often assumed to lead to a general, across-the-board enhancement in hearing, but our findings suggest that improvements may be more specific to tasks that rely on how information is processed in the brain and not at the ears, which appears to result from using auditory information more reliably. The similarity with musical experience is also interesting because it suggests that some of these improvements may reflect experience-dependent changes." 

Woon Ju Park, Georgia Institute of Technology