Choosing recording settings ― sample rate, bit depth, channels
What the numbers in Settings actually decide. The short answer first: 48kHz, 24-bit, mono will not let you down for meetings and interviews.
Sample rate ― how often the signal is measured
How many times per second the microphone signal is turned into a number. 48kHz means 48,000 times. Higher values capture higher frequencies, but 48kHz is plenty for speech. Beyond that you pay in file size and processing time without making conversation any clearer.
Higher rates matter for music and field recording. For transcription they do nothing — recognition engines downsample to 16kHz internally anyway.
Use whatever the device actually offers. Forcing a rate the hardware does not support leads to playback at the wrong speed and pitch. The iOS app follows the rate the microphone reports.
Bit depth ― how finely each measurement is stored
| Setting | When it fits |
|---|---|
| 16-bit | Consistent speech levels. Two-thirds the size of 24-bit |
| 24-bit | Default for meetings and interviews. Quiet voices survive alongside loud ones |
| 32-bit float | When levels are unpredictable. Survives being turned up later, at double the size |
16-bit hurts when a distant, quiet voice gets rounded down to something close to silence. If the person at the far end of the table is not coming through, move to 24-bit first.
Mono or stereo
For voice, mono is enough: half the size, and the transcript comes out the same. Stereo earns its place only when direction matters — a two-person interview with people seated apart, or a recording where the surroundings are part of the point.
File sizes
Roughly, per hour of WAV:
| Setting | One hour |
|---|---|
| 48kHz, 16-bit, mono | about 346 MB |
| 48kHz, 24-bit, mono | about 518 MB |
| 48kHz, 24-bit, stereo | about 1.0 GB |
| 96kHz, 32-bit float, stereo | about 2.7 GB |
WAV stores its size field in 32 bits, which caps a single file at about 4GB. At 96kHz, stereo, 32-bit float you reach that in roughly 93 minutes, and recording stops there automatically. For long sessions, turn on interval splitting.
Check the input first
Before you start, confirm the input level moves. If it does not, it is usually one of these:
- Another app is holding the microphone — a call or conferencing app
- A Bluetooth device is selected as the input and is picking up instead
- Microphone permission has been revoked