The short answer
For transcription, the format matters less than people think. WAV, M4A, and MP3 all transcribe well as long as the audio is clear and the bitrate isn't tiny. If you're recording fresh, capture uncompressed (WAV) or high-bitrate M4A/AAC. If you already have an MP3, don't re-encode it — just upload it as-is.
What actually drives accuracy is clarity: a close mic, low noise, and one speaker at a time beat any format choice.
Format by format
- WAV — uncompressed and lossless. The highest fidelity, but large files. Ideal for important recordings when storage isn't a concern.
- M4A / AAC — compressed but high quality; the default on most phones. An excellent balance of size and fidelity, and what most people should use.
- MP3 — compressed and universal. Fine for transcription at 128 kbps or higher. Below that, quality starts to hurt accuracy.
- MP4 — a video container; the audio track transcribes fine if you have a recording of a call or screen capture.
The practical rule: record in your phone's default (usually M4A/AAC), or WAV if you want maximum fidelity.
Settings that matter more than format
- Bitrate — for compressed audio, aim for 128 kbps or higher. Higher bitrate keeps more of the detail the model needs.
- Sample rate — 16 kHz is enough for speech; 44.1 kHz is fine too. Going higher rarely improves transcription.
- Mono vs stereo — speech is fine in mono. Stereo doesn't help accuracy and just doubles the file size. Diarization relies on voice characteristics, not stereo channels.
- Don't double-compress — re-saving an MP3 as another MP3 throws away detail each time. Upload the original.
A simple recipe
- Record with your phone's voice memo app (M4A/AAC) or in your transcription app directly.
- Keep the mic within arm's reach of the speaker.
- Reduce background noise.
- Upload the original file — no conversion needed.
That setup gives a clean, compact file that transcribes accurately and stays easy to store and share.
What Soria accepts
Soria transcribes the common formats — MP3, M4A, WAV, AAC, and MP4 — plus direct recording on web, iOS, and Android. Whatever your source, Soria adds speaker labels, summaries, action items, and translation across 30+ languages, so you don't have to think about codecs.
Quick answers
- What is the best audio format for transcription? WAV for maximum fidelity, M4A/AAC for the best size-to-quality balance; MP3 works fine at 128 kbps+.
- Does a higher sample rate improve accuracy? Not much — 16 kHz is enough for speech.
- Mono or stereo? Mono is fine and half the file size; stereo doesn't improve transcription.
- Should I convert my file first? No — upload the original. Re-encoding only loses detail.
