This is a spectral analysis of a recording we made tonight of a spring peeper. The fundamental or dominant frequency is consistently near 3200Hz. The male calls as loudly as possible at this pitch to attract a mate. Distinct harmonics are seen at 2x (6400Hz) and 3x (9600Hz) with overtones spaced evenly between at 1.5, 2.5, etc. Audacity is the audio tool used for presentation and analysis.