Spectral Analysis for the Ear

A central theme in elementary acoustics is that complex sounds consist of pure-tone spectral components and can be analyzed as such. To make this concept plausible it is helpful to demonstrate it in a way that has immediate appeal to the ear. The following article discusses a method for making components evident to the ear – the Cancelled Harmonics technique wherein a harmonic of a complex tone is repeatedly removed and reinserted, causing the harmonic to stand out. This effect is known to psychoacousticians as “enhancement.” Although previous demonstrations of enhancement have focused on low-order harmonics, the present research demonstrates an effect up to the 69th harmonic. It is shown that this limit is set by absolute threshold when the fundamental frequency is high. It is probably set by masking when the fundamental frequency is low.