Wave

Note: your device must be capable of recording wav files in the first place. If your device cannot, please don't blame this app.

Simplest way to record and play back wav files on your device.

-- NEW! Option to record from Bluetooth microphone
-- Records wav files to a customizable directory, with date and time stamps for file names.
-- Choose sample rate (8000, 11025, 16000, 22050, 44100)
-- Plays back last recorded wav file by default, but any wav file on the device can be played via the file picker.
-- Shows waveform for current wav file as background image.
-- Totally free and open-source; no ads.

https://github.com/yuttadhammo/androidwave

Based on Public Domain Sound Recorder by Tim Hutt:

https://play.google.com/store/apps/details?id=com.concentriclivers.soundrecorder