"Codec 2 is an open source speech codec designed for communications quality speech between 700 and 3200 bit/s." Codec2 homepage
Based on the Codec2 library (LGPL 2.1),
this Android app permits to record voice, assess the result of the
compression at self-chosen levels, and to save the compressed voice as
a *.c2 file. Codec2-encoded files can also be played back.
The Android code is based on this demo AudioRecorder app
<christian.tschudin@unibas.ch>, July 18, 2022