Are there specialized mechanisms for pitch interval perception?
Josh H. McDermott, Michael V. Keebler, Andrew J. Oxenham · The Journal of the Acoustical Society of America · 2009
Pitch intervals are a central feature of most musical systems. It has seemed likely that pitch uniquely permits precise perception of the interval by which two sounds differ, perhaps due to mechanisms specialized for music. We tested this notion by measuring interval discrimination thresholds for pitch, brightness, and loudness in the same subjects. We compared thresholds across dimensions by computing: (1) Weber fractions (the ratio of the interval threshold to the base interval size) and (2) the ratio of the interval threshold to the basic discrimination threshold for a dimension. We found that Weber fractions were comparable across dimensions (although Weber’s law did not hold, as thresholds were roughly constant across the range of interval sizes used), and that the threshold ratio was actually higher (worse) for pitch than for loudness or brightness. Interval thresholds thus provide no evidence that pitch interval perception has unusually high fidelity, as might be expected if it were the product of a specialized mechanism. The ubiquity of pitch in music may simply be due to basic discriminability, which, in contrast to interval discriminability, is far superior for pitch than for other dimensions. [Work supported by NIH grant R01DC05216.]