4242tools
← All tools

Change Audio Speed

Audio → retimed audio2 credits per file

Lectures, audiobooks, meetings, and dictation → the same recording at 0.5× to 3× speed, with the voices kept at their natural pitch.

Files are encrypted
EXAMPLE
UPLOADED — ORIGINAL SPEED
arrow_forward
RETIMED — 1.5× FASTER
lecture.mp3 → lecture-1.5x.mp3 40 min
audiobook-ch3.m4a → audiobook-ch3-1.5x.m4a 18 min
standup.wav → standup-1.5x.wav 10 min
interview.ogg → interview-1.5x.ogg 22 min

What you get

check_circleEvery file retimed to the speed you picked, from 0.5× to 3×
check_circlePitch preserved — no chipmunk voices, no slowed-down growl
check_circleOriginal format kept — an MP3 comes back as an MP3
check_circleOutputs named after the source with the speed appended
check_circleA single file downloads on its own; a batch comes back as one zip

How it works

1Upload your audioDrop in any mix of MP3, M4A, WAV, AAC, FLAC, OGG, OPUS, and WMA files — one clip or a whole batch — and pick a speed from 0.5× to 3×.
2Every file is retimedEach upload is re-encoded at the new tempo with a pitch-preserving filter, so voices keep their natural tone. No AI model touches your audio — the change is fully deterministic.
3Download the retimed filesOne output per upload, in the original format and named with the speed — lecture.mp3 → lecture-1.5x.mp3. A single file downloads on its own; a batch comes back as one zip.

Who uses this tool

EDUCATION
Lectures in half the time
Speed recorded lectures up to 1.5× or 2× and get through a course backlog without losing the natural sound of the speaker.
AUDIOBOOKS & PODCASTS
Listen faster than the app allows
Retime episodes and chapters to a fixed 2× or 3× so they play at your pace on any player, even ones without a speed control.
TRANSCRIPTION & TYPING
Dictation slow enough to type
Slow a dictated memo or interview to 0.75× or 0.5× so your typing keeps up without constant pause-and-rewind.
TEAMS & MEETINGS
Catch up on recorded calls
Run the meetings you missed at 1.5× and still hear every word clearly — the pitch stays natural, only the tempo changes.
LANGUAGE LEARNING
Native speech at a learnable pace
Slow native-speed recordings to 0.75× so you can follow the pronunciation, without the audio dropping into a distorted growl.
MUSIC & AUDIO
Practice tracks at tempo you choose
Slow a passage down to work through it, or speed a reference up — the key stays the same because pitch is preserved.
SECURITY

Built for sensitive documents

Bank statements, medical files, case records. Security isn't a feature we added — it's the foundation.

lock
Encrypted in transit
Encrypted in transit over TLS 1.2+, and stored in access-controlled, encrypted object storage. Files are protected the moment they leave your browser.
admin_panel_settings
Your files stay yours
Workspaces are isolated per account. Role-based access shows teammates only what they need.
auto_delete
Deleted, not stored
Files are deleted after processing. Everything runs on our own hardware and is never sent to an outside AI service, so your data is never used to train models.
dnsProcessed on our own hardwareauto_deleteDeleted after processinglockEncrypted in transit

Questions

No. The tempo is changed with a pitch-preserving filter, so voices keep their natural tone — no chipmunk effect when speeding up and no deep growl when slowing down. This also means it is not a pitch shifter: if you want the key of a track changed, this tool will not do that.

Related tools

More in Media & video

Try it free. 50 credits every month.
No card needed. Files are deleted after processing.
Change Audio Speed: Speed Up or Slow Down Audio Without Pitch Change — 42tools