Understanding music: humans identify changes in low-pitch tones more easily


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Canadian researchers recently carried out auditory-scene analysis testing among a group of volunteers and found that low-pitched tones are more easily identified. The team of researchers with specialists in psychology, neuroscience, behavior and music, set out to test responses to a simultaneous stream of high-pitched and low-pitched tones. They asked 35 volunteers fitted with electroencephalography (EEG) sensors to listen to two simultaneous streams of computer-synthesized piano tones, each of a different pitch. A tenth of the time, the lower tone was presented 50 milliseconds too early, and another tenth of a time, the higher tone was also played 50 milliseconds before expected. The aim was to identify when the volunteers found tones with abnormal timing, a spike of electrical activity known as mismatch negativity (MMN).

The study showed that MMN signals were consistently larger when the lower note was mistimed, in comparison to the higher note. They also tested the ability of participants to adjust their finger-tapping to the variable timings of the music they were played, and found that adjustments were more accurate for lower tones. The researchers suggest that human hearing may have evolved to make these low-pitch distinctions.

Polyphonic music most often conveys melody in higher-pitched sounds but rhythm (temporal foundation) in lower-pitched sounds. According to the authors, “these musical conventions likely arise from very basic auditory physiology.” These findings on sensitivity to low-pitch tones help to explain why the music of so many cultures uses low-pitch for rhythm and higher pitch for melody.

Source: Hove MJ, et al. Superior time perception for lower musical pitch explains why bass-ranged instruments lay down musical rhythms. Proceedings of the National Academy of Sciences 2014 Jun 30; MailOnline