audio/basic

MIME's original idea of sound, defined in RFC 2046 as the deliberate lowest common denominator: single-channel 8-bit µ-law PCM at 8000 Hz — telephone quality, chosen because in 1996 that was the one encoding every system could decode. The registry maps it to the Sun and NeXT .au and .snd extensions, though strictly the RFC describes raw headerless samples while .au files add their own .snd container header. It has no modern sending use — voicemail systems and unix workstation beeps were its natural habitat — but it remains the answer to a good trivia question: the only audio type in MIME's founding document.

.au and .snd carry a Sun header before the samples; the RFC's raw form has no header at all.

Defined by RFC 2046 · IANA registration. Registry facts from the IANA media-types registry via mime-db.