Speed Up or Slow Down Any Audio File Change the playback speed of audio files without affecting pitch.

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Audio Speed Changer

Change the playback speed of audio files without affecting pitch.

Upload Audio

Drop your audio file or click to browse.

Set Speed

Choose your desired playback speed (0.5x to 3x).

Download

Download the speed-adjusted audio file.

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What Is Audio Speed Changer?

The Audio Speed Changer adjusts the playback speed of audio files without altering the pitch. Speed up lectures for faster learning, slow down music to practice along, or adjust podcast playback speed. The tool uses the Web Audio API's playbackRate property combined with time-stretching to maintain natural pitch while changing tempo. Upload any audio format, set your desired speed multiplier, preview the result, and download. All processing happens in your browser for complete privacy.

Why Use Audio Speed Changer?

Change speed without changing pitch (time-stretching)
Wide speed range from 0.5x to 3x normal speed
Preview before downloading to verify the result
Fully client-side — no server uploads needed

Common Use Cases

Study Aid

Speed up recorded lectures to review material faster.

Music Practice

Slow down complex musical passages to practice at a comfortable tempo.

Transcription

Slow down audio for easier manual transcription.

Content Creation

Speed up or slow down audio clips for video editing and content creation.

Technical Guide

Speed adjustment uses the Web Audio API's AudioBufferSourceNode.playbackRate property in combination with an OfflineAudioContext. The source audio is decoded and played through the OfflineAudioContext at the specified playback rate. The OfflineAudioContext duration is set to originalDuration / playbackRate to capture the full time-stretched output. At playback rates other than 1.0, the browser's built-in resampling handles the time-stretching. For playback rate changes, the pitch naturally shifts proportionally — to maintain original pitch while changing speed, the tool adjusts the detune parameter: detune = -1200 * Math.log2(playbackRate) cents. This compensates for the pitch shift caused by speed change, achieving true time-stretching.

Tips & Best Practices

1
Speeds between 0.75x and 2x generally produce the best quality
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Extreme speed changes (below 0.5x or above 3x) may introduce artifacts
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Slowing down audio increases the output file size proportionally
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Speeding up audio reduces file size and duration proportionally

Related Tools

Audio Volume Changer

Increase or decrease the volume of any audio file.

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Audio Pitch Shifter

Shift the pitch of audio files up or down without changing speed.

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Audio Reverse

Reverse any audio file to play it backwards.

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Audio Trimmer

Trim and cut audio files to the exact duration you need.

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Frequently Asked Questions

Q Does changing speed affect pitch?

The tool uses time-stretching to maintain the original pitch while changing speed. You'll hear the same notes at a different tempo.

Q What speed range is available?

You can adjust speed from 0.5x (half speed) to 3x (triple speed).

Q Will the audio quality be affected?

Minor artifacts can appear at extreme speed changes. Normal speed adjustments (0.75x-2x) maintain excellent quality.

Q How long will the output file be?

At 2x speed, the output is half the original duration. At 0.5x, it's twice the duration.

Q Is this processed locally?

Yes. All speed adjustment happens in your browser. No files are uploaded.

About This Tool

Audio Speed Changer is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.