Raw audio format

RAW Audio format or just RAW Audio is an audio file format for storing uncompressed audio in raw form. Comparable to WAV or AIFF in size, RAW Audio file does not include any header information (sampling rate, bit depth, endian, or number of channels). Data can be written in PCM, IEEE 754 or ASCII.

Raw files can have a wide range of file extensions, common ones being .raw, .pcm, or .sam. They can also have no extension.

As there is no header, compatible audio players require information from the user that would normally be stored in a header, such as the encoding, sample rate, number of bits used per sample, and the number of channels.

...
Wikipedia