Remove static, hum and hiss from audio
Diffio removes static, electrical hum and hiss from speech you've already recorded, in audio or video, in your browser.
A ground loop on the mixer, a noisy preamp, an old cassette: the noise never stops, so it's the first thing a listener hears. Upload the file and hear the voice without it.
Remove hum, hiss or static from a recording
Drag an audio or video file here, orPick an audio or video file from your phone
MP3, WAV, M4A, AAC, FLAC or OGG audio, or MP4, MOV, AVI, MKV or WebM video. Up to 90 minutes and 2 GB per file.
Free plan: 3 uploads, audio or video, with a 2-minute preview of each result. Downloads and the Pro model from $8 per month.
Hiss, crackle and hum, before and after
Pick a problem, press play and switch between the original and the restored speech. Your place in the clip stays the same. Headphones help, especially for hum.
Listen for: The bright, steady hiss in the pauses between sentences, and the s and t sounds it covers.
Sample made by mixing clean speech (LibriTTS, CC BY 4.0) with a real recording of blank cassette tape hiss ("TAPE HISS Sonab c500 B" by foad, Freesound, CC0; high-passed at 1.5 kHz to drop the deck's low rumble). Restored with Diffio 4.6 Pro. Both clips are loudness-matched for playback.
- Speech: LibriTTS test-clean, speaker 237, LibriTTS (Zen et al., 2019), from a public domain LibriVox reading, CC BY 4.0.
- Hiss recording: TAPE HISS Sonab c500 B, foad, CC0 1.0.
Each pair is the clip we uploaded and the restored speech Diffio returned on November 3, 2026, with one fixed volume change so both play at the same loudness. Full credits and the sample record are published with the files.
Hum, hiss and static are three different problems
People use the three words loosely, but they sound different and come from different places, and the manual fix for each is different too.
Hum and buzz
Hum is a low, steady tone at the frequency of the mains power: 60 Hz in the US, 50 Hz in most of Europe. It usually brings multiples of that frequency along (120 Hz, 180 Hz and up), which is what makes it sound like a buzz rather than a pure tone. The usual cause is a ground loop, where two pieces of gear on different outlets are also joined by an audio cable. Audio cables lying across power cables, light dimmers and unbalanced cables on long runs pick it up too.
Hiss
Hiss is a bright, steady noise spread across the high frequencies, like air escaping. It comes from the electronics: a cheap preamp, a recorder's gain turned up to reach a quiet voice, or the tape itself on a cassette or reel. Because it's steady, it's most obvious in the pauses.
Static and crackle
Static is irregular: crackle, pops and spitting noises that come and go. Loose or damaged cables, wireless interference, a phone near the mic and worn vinyl or 78 rpm records are the usual sources.
How to prevent hum, hiss and static while recording
- Plug the audio gear into one outlet or one power strip, so it shares a ground. Unplugging a laptop's charger and running it on battery often breaks a ground loop.
- Use balanced XLR cables for long runs, and cross power cables at a right angle instead of running them side by side.
- Get the mic closer instead of turning up the gain. A voice recorded loud enough at the source leaves the preamp's hiss far below it.
- Check cables and connectors by wiggling them while you listen on headphones. Crackle that follows your hand is the cable.
- Keep phones away from the mic and interface. A phone checking in with the network can buzz through nearby audio gear.
How to remove hum, hiss and static with Diffio
- Upload the original. MP3, WAV, M4A, AAC, FLAC or OGG audio, or MP4, MOV, AVI, MKV or WebM video, up to 90 minutes and 2 GB on every plan.
- Choose a model. Diffio 4.6 Flash is fast and on every plan, including Free. Diffio 4.6 Pro restores every window 3 times and keeps the cleanest. The Pro model is included in Basic.
- Compare. Switch between the original and the restored speech on the same playhead. Listen in the pauses, where hiss and hum are easiest to hear.
- Download the restored speech or the full video on a paid plan. Every project also comes with a transcript.
You don't have to tell Diffio which kind of noise it is, or find a quiet stretch for a noise profile. It restores the speech and leaves the rest out, which also helps when a recording has hum and hiss at once. Old tapes and records often have all three. Restoring old recordings covers archive transfers in more detail.
What Diffio can't fix
- Noise louder than the voice. When the buzz or hiss drowns the speech, there is less of the voice to restore.
- Music. Diffio restores speech. Hum on a guitar track or crackle on a song isn't restored; music goes to the background track.
- Dropouts. A cable that cut out completely left silence, not a noisy voice.
- Overlapping speakers. Two people talking at once stay together in one speech track.
How to remove hum, hiss and static in Audacity, Premiere Pro and DaVinci Resolve
Steady noise is the case manual tools handle best, because they can learn it from a stretch with no speech. The more the noise changes, the less a profile helps.
Audacity (free)
- Hiss and steady static: select a second or two with only the noise, open Effect, Noise Removal and Repair, Noise Reduction and click Get Noise Profile. Then select the whole clip, open Noise Reduction again and apply it with modest settings.
- Hum: open Effect, EQ and Filters, Notch Filter and set it to 60 Hz (50 Hz for recordings made in Europe). Repeat at 120 Hz and 180 Hz for the harmonics.
- Crackle: Effect, Noise Removal and Repair, Click Removal is built for record clicks and can thin out crackle.
Adobe Premiere Pro
- Select the clip and tag it as Dialogue in the Essential Sound panel.
- Open Repair. Turn on DeHum for hum and Reduce Noise for hiss and steady static.
- Raise each amount until the noise drops, then back off if the voice starts to sound thin or watery.
DaVinci Resolve
- Drag the De-Hummer effect from the Fairlight FX library onto the clip or track and set the frequency to 60 Hz (or 50 Hz).
- For hiss, add the Noise Reduction effect from Fairlight FX and let it learn the noise from a stretch with no speech.
- Compare with the effects bypassed before you render.
When the noise changes over the clip, or hum, hiss and static are all there at once, Diffio saves you from stacking one filter on another. For the other common problems, from echo to wind, see how to make audio sound better, and for a cheap or noisy mic, fixing bad microphone audio.
Questions about static, hum and hiss
How do I remove static from audio?
Upload the recording to Diffio, let it restore the speech and compare the result with the original. In a free editor like Audacity, steady static responds to Noise Reduction with a noise profile, and crackle made of separate pops responds to Click Removal.
How do I remove background hum in Adobe Audition?
Select the audio, open Effects, then Noise Reduction / Restoration, then DeHummer. Set the frequency to the mains frequency where it was recorded (60 Hz in the US, 50 Hz in most of Europe), include the harmonics, preview and apply.
What is the difference between hum, hiss and static?
Hum is a low, steady tone at the mains frequency (60 Hz in the US) and its multiples. Hiss is a bright, steady noise across the high frequencies, from preamps, high gain and tape. Static is irregular crackle and pops, from bad cables, interference or worn records.
Why does my recording have a hum?
Usually a ground loop: two pieces of gear plugged into different outlets and joined by an audio cable. Audio cables running next to power cables, light dimmers and unbalanced cables over long runs cause it too.
Can Diffio remove hum or hiss from music?
No. Diffio restores speech. Music is separated into the background track rather than restored, so for a song or an instrument, a music restoration tool is the better fit.
Will the voice sound different afterward?
Diffio is built to keep the same voice and words with the noise removed. When the hiss or hum is louder than the voice, there is less to work with, which is why the original stays in the player next to the result.
Is it free to try?
Yes. The Free plan includes 3 uploads, audio or video, with a 2-minute preview of each result on Diffio 4.6 Flash. Full playback, downloads and the Pro model start with Basic at $8 per month. See plans and limits.
Turn down the buzz under the voice
Upload a recording with hum, hiss or static and hear the restored speech next to the original. Results depend on the recording, which is why the first 3 are free.