Figure 4.

Stimulus protocol for investigating cortical neural correlates of harmonicity in ferrets. Neural activity is recorded for a sequence of complex tones and a pure tone (anchored tone sequence), all of which share a component at the BF of the neuron under investigation. If cortical (or upstream) neurons treat harmonic sounds in a special manner, then the component at BF should elicit a qualitatively different response when presented in a harmonic context compared to an inharmonic context.