Frequency counter based on the microphone input. Counts when the input rises or falls past a set level and converts into into frequency or a time period. FOR INDICATION ONLY. Results depend on your device and its hardware. If you just want to know the frequency of a sound with harmonics (e.g. musicial instrument), a FFT based app such as keuwlsofts spectrum analyser or guitar tuner will be better. This app can provide more accurate frequency measurement for single frequency input signals