undetectable.me

Recording-time (ENF) remover

Remove the mains hum that can date a recording

Almost every indoor recording picks up a faint hum from the mains, at 50 Hz in most of the world or 60 Hz in North America. That hum, the Electric Network Frequency, wobbles in exact step with the power grid, so its pattern can be matched against grid logs to work out when a clip was recorded. This notches out the hum and its harmonics so that time-stamp is gone, on your device.

Runs entirely in your browser. Your file is never uploaded or stored.

Why the hum is a time-stamp

The grid does not hold its frequency perfectly. It drifts up and down by tiny amounts, second to second, and that wander is logged and roughly the same across a region. A recording made off the mains carries the same wander in its hum, so matching the two lines the clip up against a moment in time. Notching the hum out removes the pattern there is nothing left to match.

Pick the right frequency and harmonics

Choose 50 Hz for most of the world or 60 Hz for North America. If you are not sure where a clip was recorded, pick Both to notch 50 and 60 Hz together, the extra notch on the wrong frequency is inaudible. The harmonics slider also removes the overtones at multiples of the base frequency, where the hum energy often sits; four is usually enough, more is more thorough but touches slightly more of the low end.

What this does not do

This removes the mains-hum time signature. It does not remove other time cues you might have left, such as clocks or background audio, and it is not a general noise reducer.

Compare, then download in any format

After you apply, the Before and After players sit side by side so you can hear that only the hum is gone and the rest is untouched. Then download the result as lossless WAV or FLAC, so the notching is not smeared by re-compression, or as a smaller MP3, M4A or Opus. M4A and Opus are offered only when your browser can create them.