Speed ratio
Choose a multiplier relative to the source and show the calculated duration before processing.
Change Audio Speed
Make speech, music or a practice track faster or slower. Compare the new duration, preserve pitch when the verified time-stretch engine supports it, and export a separate file.
Speed range, pitch-preservation algorithm, fade behavior, formats and limits must be read from source code. Do not call a basic resampler “pitch preserving.”
Read the full guide1
Add audio
or click to choose a file
2
Adjust Speed
Speed preview
3
Download
Download your processed audio
Drop an audio file here
or click to choose a file
Supported formats: MP3, WAV, M4A, AAC, OGG, FLAC, Opus
Maximum file size: 200 MB
Change duration without intentionally shifting musical pitch when the verified algorithm supports it.Preserve pitch
0.25x0.5x1x1.5x2x4x
No audio files have been added yet.
00:00
00:00
Original duration-
New duration-
Speed1.25x
Format—
Bitrate128 kbps
Output settings
Confirm whether decoding, time stretching and encoding run in the browser or call a service. A remote URL is still downloaded from its host. Avoid saying files are “deleted after processing” when local files were never uploaded in the first place.
What changes when audio speed is adjusted?
Changing speed changes duration: a 2× result is about half as long, while 0.5× is about twice as long. Simple resampling also changes pitch; a real time-stretch algorithm can aim to keep pitch, but extreme ratios may still create artifacts.
Speed-changing options
Pitch handling
Offer Preserve pitch only when an actual time-stretch implementation is active; otherwise explain that pitch changes with speed.
Preview before export
Listen to a representative section because intelligibility and artifacts vary across voices, music and ratios.
Finishing controls
Use fades to soften abrupt edges and optional normalization only when the output path implements them correctly.
When changing speed helps
- Slow down speech for transcription or language practice.
- Speed up a lecture, meeting or podcast for review.
- Reduce music tempo for instrument rehearsal while keeping the key when supported.
- Create a fast or slow sound-design effect where pitch shift may be intentional.
- Match the duration of narration or audio to another timeline before editing.
How to change audio speed
Load the audio
Choose a supported file or direct URL and confirm its source duration.
Set the ratio
Move the speed control or choose a preset, then check the calculated output duration.
Choose pitch behavior
Enable pitch preservation for speech or music only if the implementation confirms a time-stretch engine; disable it for tape-style effects.
Preview and refine
Listen to several passages, especially consonants, percussion and sustained notes. Adjust fades or normalization if available.
Export and compare
Create the file, then verify total duration, pitch, intelligibility, transitions and synchronization with any target media.
How the controls affect sound
Speed multiplier
Values below 1× lengthen the audio; values above 1× shorten it. The exact allowed range must come from the engine.
Preserve pitch
Time stretching tries to hold musical pitch while changing duration. It may smear transients or add metallic texture at extreme settings.
Fade in and fade out
Short fades reduce clicks at the beginning and end. They do not repair internal edit points.
Normalize
Normalization can scale the finished waveform to use available headroom. It does not restore dynamics or guarantee a streaming loudness target.
Quality mode
Higher-quality analysis may take longer and use more memory. Only expose quality levels that map to real processing modes.
How the file is processed
Confirm whether decoding, time stretching and encoding run in the browser or call a service. A remote URL is still downloaded from its host. Avoid saying files are “deleted after processing” when local files were never uploaded in the first place.
Time-stretch limitations
- Extreme slowdowns and speedups can create warbling, smearing or robotic artifacts.
- Pitch preservation is not the same as source separation and cannot isolate voice or instruments.
- Changing speed can alter perceived rhythm, pauses and synchronization with video.
- Codec and output support vary by browser and bundled encoders.
Better results
- Use smaller steps and preview rather than jumping directly to an extreme ratio.
- For transcription, prioritize intelligibility over natural rhythm.
- For music practice, listen for transient smearing and tuning drift.
- Export lossless when another editing stage will follow and the engine supports it.
Common speed-change issues
The voice sounds high or low
Pitch preservation is off, unsupported or not functioning. Enable a verified time-stretch mode or choose a ratio closer to 1×.
The result sounds metallic
Extreme stretch ratios and complex music challenge the algorithm. Move closer to 1× or select a higher verified quality mode.
Duration is not exactly the estimate
Encoder delay, rounding and source timestamps can cause a small difference. Display the actual result duration after encoding.
Export is slow
Time stretching must analyze and synthesize the whole file. Long stereo audio and high-quality modes require more CPU and memory.
Audio speed changer FAQ
Can I slow audio without lowering the pitch?
Yes only when a pitch-preserving time-stretch algorithm is implemented. Basic playback-rate or resampling changes pitch together with speed.
How does 1.5× affect duration?
The theoretical duration is the original divided by 1.5, with small differences possible from encoding and rounding.
Will changing speed reduce quality?
It can. Time stretching synthesizes new samples, and extreme ratios create more artifacts. Lossy re-encoding can add further loss.
Can I speed up a podcast or lecture?
Yes. Preview speech at the intended ratio and check that words, pauses and speaker changes remain understandable.
Can I use this for music practice?
Yes when pitch preservation is available, but listen for rhythm and transient artifacts before relying on the result.
Does normalization make the audio clearer?
No. It changes level, not intelligibility, noise or time-stretch artifacts.
Are files uploaded?
Only state local processing after verifying the full decode, stretch, preview, encode and telemetry path. URL sources are fetched from their host.
Does the original file change?
No. The tool should create a new file with a changed duration.