MP3 vs. WAV: what's different
MP3 is compressed and small, ideal for sharing and podcasts; WAV (and AIFF) is uncompressed and larger, the format you want for masters and further editing. Silence removal works on both — the difference is only quality and size. The key is to cut without re-encoding, so an MP3 stays the same bitrate and a WAV stays lossless.
Why most iPhone editors can't touch audio files
The popular mobile editors are video-first. Hand them an MP3 or WAV and there's often nowhere to import it. To trim audio-only files you need a tool that treats audio as a first-class input — which is exactly what a dedicated silence remover does, opening MP3, WAV, AIFF and M4A directly.
Step by step: trim silence from an MP3
Import the MP3 from Files or iCloud, set a threshold just below the speaking (or singing) level so quiet passages aren't mistaken for silence, choose a minimum silence length, add a little padding, and preview. When it sounds right, export — on-device, with nothing uploaded.
Same for WAV, AIFF and M4A
The workflow is identical for lossless formats. Because the edit is a cut-and-join rather than a re-encode, a WAV or AIFF master stays lossless through the trim — no generation loss — which matters if the file is headed for mastering or an audiobook pipeline.
Settings for music vs. speech
Speech tolerates a firmer cut: a threshold just under talking volume and a minimum length around half a second. Music needs care — quiet passages and reverb tails can read as silence, so raise the threshold and lengthen the minimum so you don't clip the ends of notes. Preview a section either way before committing.
Export without losing quality
Keep the output in the same lossless format for masters (WAV/AIFF), or a matching bitrate for MP3. Since removing silence only deletes silent segments and rejoins the rest, the parts you keep are untouched — your audio sounds exactly as recorded, only tighter.