SOLIPSIUMAlpha

SOLIPSIUM Super resolution audio engine

Free audio tool

Speed a recording up or slow it down, with its pitch kept.

Choose a speed from 0.5 to 2 times. Your browser keeps the voice at its own pitch, or lets the pitch move with the speed like a tape. Nothing is uploaded.

Drop a recording here

Your browser does the work on this device. Nothing is uploaded.

WAV, MP3, M4A, FLAC, OGG, Opus and more, up to 30 minutes or 200 MB.

Choose a file

Two ways

Keep the pitch, or move it.

A tape played faster sounds higher. Keeping the pitch takes another method.

Keep the pitch.

WSOLA cuts the recording into slices 40 ms long and lays them back closer together or further apart, each moved by up to 10 ms to where it most smoothly continues the last. Voices stay at their own pitch.

Like a tape.

Every sample is read faster or slower, so pitch and speed move together: twice the speed is an octave higher.

Every channel together.

The slices are cut at the same places in every channel, so stereo stays in step.

How it works

From half speed to twice as fast.

The new length is the old one divided by the speed.

  1. Choose the speed.

    1.25 makes a 30-minute lecture last 24 minutes; 0.75 makes a fast speaker easier to follow.

  2. Choose the way.

    Keep the pitch for speech; like a tape for an effect, or to undo a recording made at the wrong speed.

  3. Save it.

    As an MP3 at 192 kbps or a 16-bit WAV, at the file's own sample rate.

Questions

About speed.

Does it sound natural?

Speech changed by a little, from 0.8 to 1.3 times, keeps its sound well. Far from 1, and on music, the slices can be heard as a slight flutter. Listen before you save.

A tape captured at the wrong speed?

Use like a tape, at the ratio between the two speeds: a tape recorded at 1.875 inches a second and played at 3.75 is fixed at 0.5.

Change the pitch only?

This tool changes speed. Changing pitch alone is not one of the free tools.

How long can the recording be?

Up to 30 minutes, the length every free tool opens, and the result can be up to 30 minutes too: slowed to half speed, a recording of up to 15 minutes fits.

Is my recording uploaded?

No. Your browser opens the file and does the work on this device; nothing is sent to Solipsium. Checking a recording for noise, hum and clipping is another page: the home page checks it in your browser too.

Free audio tools

Related free tools.

For long recordings.

Hard to follow for another reason?

Noise and echo make speech hard to follow at any speed. Drop the recording on the home page to check it, and hear its first 20 seconds repaired.

Check a recording

The check and the 20-second try need no account.