How to bleep personal info in audio recordings — free, no upload
- Step 1Open the redactor and drop your recording — Drop the recording onto the redactor. Accepted input is audio (MP3, WAV, FLAC, M4A, OGG, Opus). The Pro-tier limits apply: 200 MB and up to 120 minutes per file.
- Step 2Let the file decode in your browser — The tool decodes the audio locally to read its duration. Nothing is uploaded — FFmpeg 8.1 runs as WebAssembly inside the page, so the recording never leaves your device. The decoded duration becomes the upper bound for every range you add.
- Step 3Add a redaction range — Click Add range. A row appears with Start and End number inputs (in seconds). A new range defaults to 0 s to 1 s; type the real start and end of the segment you want silenced.
- Step 4Mark every segment that needs silencing — Play back the recording and add a range for each spot where personal info is spoken. There is no auto-detection, so you decide the boundaries — pad each range a few hundred milliseconds on both sides so the first and last syllable are fully inside the muted window.
- Step 5Process the file — Run the tool. For each range it applies
volume=0gated tobetween(t, start, end), so the audio inside every marked range becomes pure silence. The rest of the timeline is untouched and the file is re-encoded to the output format. - Step 6Download and verify — Listen back to the
-redacteddownload across each boundary. Confirm the personal info is gone and that no leading/trailing fragment slipped through; if it did, remove that range, widen it, and reprocess.
What the redactor actually does
Every row verified against the browser processor and the range UI. The tool mutes — it does not bleep, beep, or insert noise.
| Behaviour | Implementation | What it means for you |
|---|---|---|
| Redaction method | Volume set to 0 (full silence) inside each marked range via the FFmpeg volume filter with an enable='between(t,start,end)' gate | No tone, beep, or noise is inserted — the range goes silent |
| Marking | Manual only — you add ranges with Add range and type Start and End in seconds | There is no auto-detection, transcription, or phone-number finder in the tool |
| Time granularity | Start/End inputs step in 0.1 s (100 ms) increments | Type a finer value directly if your browser allows; the filter uses your exact number |
| Range bounds | Each input is clamped to min 0 and max = the file's decoded duration | You cannot mark a range past the end of the file |
| Output format | Defaults to the input file's extension and is re-encoded through FFmpeg | Lossy inputs (MP3/M4A/OGG/Opus) are re-compressed; WAV/FLAC stay lossless |
| Filename | Original name with a -redacted suffix | e.g. interview.mp3 becomes interview-redacted.mp3 |
| Empty input guard | Throws Add at least one redaction range if no range is set | At least one Start/End pair is required before processing |
Input and output formats
Output is re-encoded through FFmpeg 8.1 (WebAssembly). The output extension follows the input by default; the encoder is chosen from that extension.
| Format | Output encoder used | Lossy on re-encode? |
|---|---|---|
| MP3 | libmp3lame | Yes — re-compressed (one extra lossy generation) |
| WAV | pcm_s16le | No — lossless PCM |
| FLAC | flac | No — lossless |
| M4A / AAC | aac | Yes — re-compressed |
| OGG (Vorbis) | libvorbis | Yes — re-compressed |
| Opus | libopus | Yes — re-compressed |
Audio tier limits that apply to redaction jobs
PII redaction runs inside the audio tool family, so the audio family limits apply. Numbers are per the live tier table; durationMin is a per-file duration cap that is separate from the file-size cap.
| Tier | Max file size | Max duration / file | Files per job |
|---|---|---|---|
| Free | 50 MB | 30 min | 1 |
| Pro | 200 MB | 120 min | 10 |
| Pro-media | 100 GB | Unlimited | 100 |
| Developer | 100 GB | Unlimited | Unlimited |
Cookbook
Concrete redaction recipes for spoken personal information. Times are in seconds; type them straight into the Start/End inputs.
Blank a spoken home address in a recorded meeting
A participant reads out a full street address around the 4-minute mark. You want it silenced but the meeting's length and later timestamps preserved.
Range to add: Start: 243.4 End: 248.1 (the address spans ~4:03-4:08) Result: audio from 243.4s-248.1s is muted (volume=0) total duration unchanged output: meeting-redacted.mp3
Silence several names scattered through an interview
Three off-the-record names are mentioned at different points. Add one range per name in any order — order does not matter.
Add range 1 -> Start: 67.2 End: 68.9 Add range 2 -> Start: 512.0 End: 513.6 Add range 3 -> Start: 1041.5 End: 1043.0 All three windows are silenced in a single pass. The spans between them are untouched.
Pad a range so the trailing syllable is fully covered
On first pass, the end of a spoken surname was still faintly audible because the range ended exactly on the word. Widen the End by 0.4 s.
Before: Start: 88.0 End: 89.0 -> last syllable leaks After: Start: 87.7 End: 89.4 -> name fully muted Reprocess from the original file - redaction is non-destructive.
Keep a lossless copy when the source is WAV
Your recording is a WAV master. Leaving the output as WAV avoids any lossy re-compression on the parts you keep.
Input: board-call.wav Output format: wav (follows input) -> pcm_s16le, lossless Filename: board-call-redacted.wav The redacted spans are silent; kept audio stays lossless.
Two personal references mentioned back-to-back
Two reference numbers are read out within a second of each other. Use overlapping or adjacent ranges — the union is silenced.
Add range 1 -> Start: 300.0 End: 303.0 Add range 2 -> Start: 302.5 End: 305.0 Overlap is allowed; audio from 300.0s-305.0s ends up silent.
Edge cases and what actually happens
No range added before processing
RejectedIf you process without adding at least one range, the tool throws Add at least one redaction range. Click Add range and enter Start/End values first.
End time set before Start time
By designA range whose End is earlier than its Start silences nothing — the between(t,start,end) window is empty. Nothing breaks, but the personal info stays audible, so re-check that End is greater than Start.
Range extends past the end of the file
PreservedThe Start/End inputs are clamped to the file's decoded duration, so you cannot mark beyond the end. A range that reaches the final second simply mutes to the end of the audio.
Trailing syllable still audible after redaction
ExpectedSpeech tails off; if the End landed exactly on the word, a faint syllable can remain. Widen the range by 0.2–0.4 s on each side and reprocess. This is a marking choice, not a tool error.
Overlapping ranges
SupportedOverlapping or adjacent ranges are fine — each is an independent mute gate, so the union of all ranges goes silent. No conflict, no error.
Expecting an audible censor beep
By designThere is no beep, tone, or noise insertion. Redacted spans are silent. If broadcast-style audible censoring is required, add the beep in a separate editor; this tool only mutes.
Personal name also sits in the file's title/comment tag
Not handled hereAudio redaction does not touch ID3 tags. A name in the title or comment field survives — scrub it with id3-editor and check the filename too.
Recording longer than the tier duration cap
RejectedPer-file duration is capped by tier (Free 30 min, Pro 120 min, Pro-media/Developer unlimited). A long call needs Pro or higher; the file-size cap is checked separately.
MP3 input, MP3 output
ExpectedOutput follows the input extension and is re-encoded, so an MP3 goes through one extra lossy generation. Usually inaudible; choose WAV output if you want to avoid it entirely.
Frequently asked questions
Does the tool insert a beep, tone, or white noise over the redacted part?
No. The redactor sets the volume to 0 inside each range, so the segment becomes full silence. There is no beep tone, 1 kHz tone, or white-noise option in the tool — it is a mute, not a bleep. If you specifically need an audible censor beep for broadcast style, you would have to add it in a separate audio editor; this tool's output is silent across the marked ranges.
Can it automatically find names, numbers, or card details?
No. Marking is manual only — you add ranges and type the Start and End seconds yourself. There is no speech-to-text, entity recognition, or phone-number detector built in. Play the recording, note the timestamps where sensitive content is spoken, and enter those ranges. This keeps everything in the browser with zero upload, but it does mean you (or a reviewer) decide what gets silenced.
Can the silenced audio be recovered from the output file?
No. The samples inside each range are replaced with silence before encoding, so the original audio in those spans is not present in the output file — there is nothing to un-mute. Keep your original recording in a secure location if you ever need the un-redacted version; the redacted file cannot be reversed back to it.
Is my recording uploaded to a server?
No. All processing is 100% in your browser using FFmpeg 8.1 compiled to WebAssembly. The audio is decoded and redacted locally and never transmitted, which is what makes the tool suitable for sensitive recordings. You can disconnect from the network after the page loads and redaction still works.
How precise can the redaction boundaries be?
The Start and End inputs step in 0.1 s (100 ms) increments, and the underlying between(t, start, end) filter uses the exact number you type. For most speech that 100 ms granularity is enough to catch a spoken digit or word; pad each range by a few hundred milliseconds on both sides so the leading consonant or trailing syllable is fully covered.
How many separate sections can I redact in one pass?
As many as you need — click Add range for each section. Every range is applied in the same processing pass as its own volume=0 gate, so a call with ten scattered account numbers is one job, not ten. There is no fixed cap on range count; the practical limits are the file-size and duration caps for your tier.
Will the redacted file be the same length as the original?
Yes. Muting a range does not remove time — the silenced spans stay in place, so the total duration is unchanged. This is intentional: it keeps every later timestamp aligned with your notes, transcript, or video. If you actually want the file shorter, trim or strip silence instead.
Does redacting also remove names or numbers stored in the file's metadata?
No. This tool silences audio samples within the ranges you mark; it does not touch ID3 tags, comments, or cover art embedded in the file. If a phone number or name is sitting in the title/artist/comment fields, edit those separately with id3-editor, and consider whether the filename itself leaks anything.
Will redacting reduce the audio quality of the parts I keep?
The output is re-encoded through FFmpeg, so a lossy input (MP3, M4A, OGG, Opus) goes through one extra compression generation — usually inaudible but technically present. WAV and FLAC outputs stay lossless. If your input is MP3 and you want to minimise quality loss, you can choose a WAV output, but the file will be larger. The unredacted regions are otherwise the same content, just re-encoded.
I marked the wrong segment — how do I fix it?
Each range row has a trash/remove control. Delete the wrong range, add a corrected one, and reprocess. Because the tool is non-destructive to your source file (it produces a new -redacted output), you can re-run as many times as you like from the same original until the boundaries are right.
Should I just trim out the sensitive part instead?
Trimming with audio-trimmer physically cuts a span, which shortens the file and shifts every later timestamp — bad if you have a synced transcript, captions, or chapter markers. Redacting mutes in place and keeps the timeline intact. Trim when the sensitive part is at the very start/end and length doesn't matter; redact when it is mid-recording or timing must be preserved.
Is muting the audio enough for a compliance obligation?
Muting the spoken PII is a meaningful data-minimisation step, but it is one part of a process, not a full compliance programme. You still need to control the original recording, document what was redacted and why, and confirm no PII survives elsewhere (file metadata, filename, accompanying transcript). Scrub embedded tags with id3-editor and rename the file. Consult your Data Protection Officer for your specific obligations.
Privacy first
Every JAD Audio tool runs entirely in your browser via FFmpeg (WebAssembly) and RNNoise. Your audio files never leave your device — verified by zero outbound network requests during processing.