Change Audio Speed Without Changing Pitch (Free Tool)

To change audio speed without changing pitch, load the file into a speed and pitch tool, choose a speed such as 0.75x or 1.5x, leave the Keep pitch option ticked and export. The tool time-stretches the audio, so it gets shorter or longer while voices and notes stay at their original pitch. Speeds between 0.75x and 1.5x sound most natural.

Most media players can play audio faster, but only while you listen in that player. Sometimes you need the change inside the file: a sped-up lecture you can listen to on any device, a slowed product voice-over that has to match a longer video, a practice track for a musician, or a language lesson slowed for beginners. The catch is pitch. Change speed the simple way and voices turn into cartoons.

Free toolAudio Speed and PitchChange audio playback speed and pitch independently or preserve natural vocal tone during tempo shifts. All processing runs entirely inside your web browser.Open the tool

How to change audio speed step by step

The steps below use the Audio Speed and Pitch tool, which processes the file in your browser without uploading it.

1. Open the tool and drop your file onto the “Drop your audio file here” box. MP3, WAV, M4A, AAC, OGG, FLAC and Opus are accepted.
2. Under Speed, pick a chip: 0.25x, 0.5x, 0.75x, 1.25x, 1.5x, 2x, 3x or 4x.
3. Make sure Keep pitch (voices stay natural) is ticked. It is on by default.
4. Leave Pitch shift (semitones) at 0 unless you deliberately want the key to change as well.
5. Pick a Bitrate chip: 96, 128, 192 (recommended), 256 or 320 kbps.
6. Choose the Output format: MP3, WAV, FLAC, M4A (AAC), AAC, OGG (Vorbis) or Opus.
7. Click Apply. On first use the browser downloads the processing engine once (about 30 MB).
8. Listen to a section with speech or sustained notes in the preview, then click Download.

Free toolAudio Speed and PitchChange audio playback speed and pitch independently or preserve natural vocal tone during tempo shifts. All processing runs entirely inside your web browser.Open the tool

Speed, duration and pitch at a glance

Speed changes duration in a predictable way: the new length is the original divided by the speed. What happens to pitch depends entirely on the Keep pitch option.

Speed	60-minute file becomes	Pitch with Keep pitch on	Pitch with Keep pitch off	Typical use
0.5x	120 minutes	Unchanged	One octave lower (-12 semitones)	Transcribing fast passages, learning riffs
0.75x	80 minutes	Unchanged	About 5 semitones lower	Language practice, dense tutorials
1.25x	48 minutes	Unchanged	About 4 semitones higher	Podcasts and interviews
1.5x	40 minutes	Unchanged	About 7 semitones higher	Lectures and familiar material
2x	30 minutes	Unchanged	One octave higher (+12 semitones)	Skimming recordings you already know
3x-4x	20-15 minutes	Unchanged but heavily artifacted	Very high, not recognizable	Finding a spot in a long recording

The semitone figures come from music math: doubling the playback rate raises pitch by exactly one octave, or 12 semitones, and every other factor falls on a logarithmic curve between those points.

Time-stretching versus the vinyl effect

What Keep pitch actually does

With Keep pitch on, the tool time-stretches the sound. It chops the audio into very short overlapping slices and then drops or repeats slices to shorten or lengthen the file, while each slice keeps its original frequency. Speech stays recognizably the same speaker, and a song stays in the same key.

What happens with Keep pitch off

Untick the option and the tool changes the playback rate instead, exactly like spinning a record faster or slower. Speed and pitch move together. That is the right choice when the pitch change is the point, for example a deliberately slowed, deeper version of a music loop, and the wrong one for anything with a voice that should sound natural.

Where artifacts come from

Time-stretching is not free. The further you move from 1x, the more slices get dropped or repeated, and the seams become audible as a watery, phasey or slightly robotic texture. Speech usually stays clear up to about 1.5x; beyond that, consonants start to blur and comprehension drops for most listeners. Slowing down below 0.75x makes reverb tails and breaths sound smeared. Music with sharp drum hits shows artifacts earlier than a single spoken voice.

Practical tips for common jobs

Lectures and meetings recorded as video. The tool accepts audio files only. Extract the MP3 audio track from the MP4 video first, then speed up that file. You end up with a small file that plays at your chosen speed on any device.

Voice memos from phones. iPhone recordings usually arrive as M4A. You can process them directly and export MP3, or, if you want a clean MP3 version of the original as well, convert the M4A recording to MP3 and keep both.

Fitting a voice-over to a video. Work out the factor by dividing the audio length by the target length. A 66-second voice-over for a 60-second video needs 1.1x, which is not one of the chips, so pick the nearest chip that makes the audio short enough (1.25x) and trim or pause the video accordingly, or re-record with a tighter script.

Keeping quality for later edits. If the result will be edited again, export WAV or FLAC. For final delivery, the Audio Converter for MP3, WAV, FLAC, M4A and OGG can produce whatever format your platform requires. For a deeper explanation of bitrates and formats, read the complete guide on how to convert audio files in your browser.

Common mistakes

• Unticking Keep pitch by accident: a 1.5x lecture comes out sounding like a cartoon. Check the box before clicking Apply and listen to the first voice passage in the preview.
• Going straight to 2x or higher for speech: the recording saves time but becomes tiring or hard to follow. Start at 1.25x, then try 1.5x if it is still comfortable.
• Entering a pitch shift while only wanting a speed change: the key or voice tone moves unexpectedly. Leave Pitch shift (semitones) at 0 for plain tempo changes.
• Processing an already sped-up file again: artifacts from both passes stack and the audio turns metallic. Always start from the original recording and choose the final speed in one pass.
• Exporting at a low bitrate after stretching: stretched audio already has subtle artifacts, and a 96 kbps export makes them more obvious. Use 192 kbps or higher, or a lossless format.

Frequently asked questions

What is the difference between Keep pitch on and off? With Keep pitch on, only the tempo changes and voices keep their natural tone. With it off, speed and pitch change together like a record played too fast or too slow, so 2x sounds an octave higher and 0.5x an octave lower.

How long will my recording be after speeding it up? The new length is the original length divided by the speed. A 60-minute lecture becomes 48 minutes at 1.25x, 40 minutes at 1.5x and 30 minutes at 2x.

Why does sped-up audio sound watery or robotic? It sounds watery because time-stretching has to remove or repeat tiny slices of sound, and the seams become audible at extreme settings. Stay between 0.75x and 1.5x for speech and music you will listen to closely.

Can I slow down a song to learn it without changing the key? Yes, choose 0.75x or 0.5x and keep the Keep pitch option ticked. The song plays slower in its original key, so you can practice along with your instrument tuned normally.

Wrapping up

Changing speed without changing pitch is a time-stretch, and it works best in moderation. Pick the speed from the duration you need, keep the pitch option ticked, start from the original file and listen before you download. When you are ready, open the free Audio Speed and Pitch tool and adjust the tempo right in your browser.