How to trim audio and make a quiet recording louder
Most recordings need two things before anyone else hears them: the dead air, false starts and noise at either end cut away, and a level that does not make the listener reach for the volume button. Both are simple once you know what the controls do. This guide walks through trimming with Audio Trimmer, removing a slip from the middle, softening the edges, and making a quiet recording louder without the harsh crackle that comes from pushing it too far.
Cutting to the part you need
- Open Audio Trimmer and add one MP3, WAV, M4A, FLAC, Ogg or WebM file of up to 15 minutes. The waveform appears once the browser has decoded it.
- Drag across the waveform to select what to keep, then drag the handles to refine it. Tap to place the playhead and listen; Start here and End here, or the [ and ] keys, set the edges at the playhead, and Space plays the selection.
- For fine cuts, press Zoom to selection to spread the selection across the full width, or open Exact times and type the start and end to a hundredth of a second.
- Play the selection once more, choose a format, and click Trim audio.
Cut on a pause rather than in the middle of a word. The waveform makes pauses easy to see: they are the flat stretches between the peaks of speech or the beats of music.
Removing a cough, a mistake or an ad
Sometimes the problem is in the middle. Choose Remove selection, select the part to take out, and the tool keeps everything else and joins the two sides with a 12-millisecond crossfade. That is too short to hear as a fade but long enough to stop the click you get when two waveforms are butted together at different heights. Play the cut to hear a few seconds either side of the join before saving.
One edit per run keeps things predictable. For several separate cuts, download the result, open it in Audio Trimmer again and make the next cut on the new file.
Fades: softer starts and endings
A clip that starts at full volume in the middle of a sound can feel abrupt, and one that stops mid-note sounds broken. Open Fade edges and add a fade in, a fade out, or both, up to five seconds each. Half a second is enough to remove a click; two or three seconds make a music excerpt end gracefully. The preview plays the fades, so you can hear them before you save.
Making it louder without distortion
Digital audio has a ceiling. Every sample sits between minus one and plus one, and a boost that pushes peaks past that ceiling flattens them, which is the crackle people call clipping. The trouble is that how loud something sounds depends on its average level, while clipping depends on its loudest instant. A voice memo recorded far from the phone can be both quiet on average and close to the ceiling on a single consonant.
Open Volume in Audio Trimmer and you get three choices:
- Original keeps the level as recorded.
- Even out measures the loudness of the saved part the way broadcasters do (ITU-R BS.1770, in LUFS) and brings it to about −16 LUFS, a comfortable level for podcasts, voice notes and most music on phones. It never lets a peak go above −1 dBFS, so it will stop short of the target rather than distort. A loud recording is turned down to the same level.
- Custom changes the level by up to 12 dB either way. About +10 dB sounds roughly twice as loud. If a boost pushes peaks past full scale they are limited, and the result says so; choose a smaller boost or Even out if you hear harshness.
The preview plays the original volume; the saved file carries the change, and the result line shows exactly how many decibels were applied. Volume cannot remove background hiss or hum: turning a recording up turns its noise up too.
Choosing a format
MP3 plays everywhere and is the usual choice for sharing. M4A (AAC) is a little more efficient and suits Apple devices. WAV and FLAC keep the decoded sound without further loss; FLAC is the smaller of the two. Converting a compressed file to WAV or FLAC does not restore detail it already lost. For an iPhone ringtone, press Ringtone: it keeps 30 seconds from the start point and saves an M4R, and iPhone rejects ringtones longer than 40 seconds.
Everything happens on your device. The file is decoded and encoded by your browser, the original stays untouched, and the title, artist and cover art tags are copied into the new file.