A free program for Android, by keuwlsoft.

Audio Frequency Counter is a simple and useful application for your Android devices. It can detect the frequency of an audio signal and display the result in both kilohertz and hertz.

The app has several options for the user to choose from:

The first is the selection of the audio source, either from the device’s microphone or from a file on the device. The source can be either live or recorded.

The second is the setting of the threshold for the audio signal. This can be done in a simple way, either by using a volume indicator or by using a mic indicator and setting the threshold based on the volume level.

The third is the setting of the sampling frequency of the recorded signal.

The fourth is the display of the results.