Audio Frequency Counter. Requires Android 7 (Nougat) or above. App Version 1.30. No Ads. Privacy policy.

This app is similar to a frequency counter that you might find in any scientific lab. Rather than using an electrical input, it uses the microphone and is more limited in its frequency capability.

Link to app on website: https://www.keuwl.com/AudioFrequencyCounter/

App Summary:

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. musical instrument), a FFT based app such as keuwlsofts spectrum analyser or guitar tuner will be better. This app can provide a much more accurate frequency measurement for single frequency input signals.

Features include:

Displays triggered event count and frequency or time period.

Graph of input signal, 2.5 ms/div up to 640 ms/div.

Gate time of 0.1s, 1s, 10s or 100s.

Gain from x1 to x1000.

Trigger on rise or fall.

AC or DC coupling.

Set a noise level so new event is not triggered until the signal has first passed this level.