How to transcribe MP3 files

MP3 is the default recording format for more devices and apps than any other — old phones, standalone recorders, exported voicemail, downloaded podcast episodes. Most of the time, transcribing one is no different from transcribing any other audio file. There's exactly one MP3-specific thing worth knowing before you do.

Bitrate matters, but only at the low end

MP3 is a lossy format — it throws away audio detail to keep the file small, and how much it throws away depends on the bitrate it was encoded at. At 96kbps and above, which covers the vast majority of MP3s you'll ever run into, there's enough detail left for a transcription model to work with easily. It's the low end — 32 to 64kbps, common on old voicemail exports and some ancient recorder apps — where enough detail gets thrown away that quieter speech or background voices can start getting mistranscribed.

There's no reliable way to tell the bitrate just by looking at a file, and it's rarely worth checking — if a transcript comes back with more errors than you'd expect from a clear recording, a low bitrate is a reasonable first thing to suspect, especially for a file that's been forwarded through a few messaging apps and re-compressed each time.

MP3 to Text handles the format directly, at any bitrate — there's nothing to convert or check first. If accuracy on a specific file looks off, the original un-forwarded copy of the recording, if you still have it, is usually the fastest fix.