Simple frequency ratios naturally make precisely perceived melodies

Laurent Demany, Catherine Semal Daniel Pressnitzer
Current Biology. 2025-03-01; :
DOI: 10.1016/j.cub.2025.02.030

PubMed

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1. Curr Biol. 2025 Mar 6:S0960-9822(25)00193-9. doi: 10.1016/j.cub.2025.02.030.
Online ahead of print.

Simple frequency ratios naturally make precisely perceived melodies.

Demany L(1), Semal C(2), Pressnitzer D(3).

Author information:
(1)Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS,
Université de Bordeaux, Bâtiment BBS, 2 rue Dr. Hoffmann Martinot, 33000
Bordeaux, France. Electronic address: .
(2)Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS,
Université de Bordeaux, Bâtiment BBS, 2 rue Dr. Hoffmann Martinot, 33000
Bordeaux, France; Ecole Nationale Supérieure de Cognitique, Bordeaux INP, 109
avenue Roul, 33400 Talence, France.
(3)Laboratoire des Systèmes Perceptifs, Département d’Études Cognitives, École
Normale Supérieure, CNRS, PSL University, 29 rue d’Ulm, 75005 Paris, France.

Almost all human music is built on discrete scales of pitch.1 Culturally
prominent scales, such as the diatonic major scale of Western music, make use of
the simple frequency ratios 2:1, 3:2, and 4:3 between notes.2 It is generally
believed that these ratios were chosen to optimize the consonance of
simultaneous notes.3,4,5,6,7 Alternatively, or in addition, it is conceivable
that these ratios are intrinsically advantageous for the perceptual encoding of
melodies.8,9,10,11,12 Here, we provide behavioral support for this hypothesis.
In three experiments, young Western adults had to detect pitch anomalies (« sour
notes ») in partly random pure-tone melodies based on various musical scales,
including novel ones. The task did not require any musical knowledge. Most
importantly, the listeners were extensively trained in order to saturate
familiarity with the scales: for a given scale and listener, more than 2,000 (up
to 5,280) trials were run. Practice largely improved performance. This occurred
even for the diatonic major scale, suggesting that performance in our task was
not biased by previous musical enculturation.13,14 Frequency ratio simplicity
also favored performance. Crucially, its benefit was not smaller in the final
test sessions, when performance for each scale was presumably optimal and no
longer improvable by practice, than in the initial test sessions. Thus,
frequency ratio simplicity appeared to be intrinsically advantageous, rather
than advantageous merely due to familiarity. The naturalness of melodic
intervals defined by simple frequency ratios is likely to have contributed to
the cultural selection of musical scales.