A headerless file of Dialogic/OKI ADPCM audio data commonly comes with the extension .vox. This ADPCM data has 12-bit precision packed into only 4-bits.
an audio format from Apple that was developed to remove the limitations of AIFF and WAV formats. This is a container that can store sound encoded by various algorithms and track metadata. Its characteristic feature - the format doesn’t have limitations on file size and so this allows one to store infinitely long recordings.