Beat Deafness

But did you know that these things are difficult, if not practically impossible, for some people? A few years ago, scientists discovered a condition called beat deafness.

People with this disorder can’t pick out a rhythm in a piece of music or move with the beat. Hearing acuity is usually unaffected, meaning that the person can hear very quiet sounds normally and understand speech well. The problem is more in the brain, in the part that processes rhythm. However, we haven’t been able to identify the exact cause of this condition.

When a sound reaches the outer ear (pinna), it is directed to the auditory canal, then vibrates the eardrum and ossicles of the middle ear before reaching the inner ear. Sound picked up by the cilia in the inner ear is then directed to the auditory nerve and begins its journey to the brain, where auditory information is processed. The right hemisphere of the brain, specifically the right auditory cortex, allows us to distinguish the notes in a melody, while the left auditory cortex analyzes the rhythm. It’s the latter part that has an abnormality in people with beat deafness.

It is estimated that 3–4% of the population is born beat deaf. One of the first cases studied was tested in Montréal. The subject was able to keep a beat by clapping his hands when there was no sound source. The problem only arose when he was asked to do the same thing, but to the beat of some music. He had more trouble detecting changes in speed during the song, and it took him much longer to get used to them. This showed that he had trouble analyzing the music and using gestures to reproduce what he heard.

Beat deafness is as varied as the people who have it. It can manifest in different ways. For example, one participant in the rhythm deafness study was perfectly able to follow the music by clapping her hands. However, if a metronome was turned on at the same time as the music, the participant could not determine whether the two were synchronized. What’s more, someone living with Parkinson’s disease or other brain lesions that affect the left auditory cortex may have symptoms of beat deafness, even though the condition is usually present from birth.

The test used to determine whether a person has beat deafness is called the Battery for the Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA). However, this test is only conducted in university neuroscience research programs. As a result, it isn’t easily accessible. Scientists are continuing to research beat deafness.