The uniqueness of human music relative to speech and animal song has been extensively debated, but never directly measured. To address this, we applied an automated scale analysis algorithm to a sample of 86 recordings of human music, human speech, and bird songs from around the world. We found that human music throughout the world uniquely emphasized scales with small-integer ratios, particularly a perfect 5th (3:2 ratio), while human speech and bird song showed no clear evidence of scale-like tuning. We speculate that the uniquely human tendency toward scales with small-integer ratios may have resulted from the evolution of synchronized group performance among humans.
Toward automatic comparison of visualization techniques: Application to graph visualization
