Support

How do I repair a recording?

Open DeHum and choose a file, or pick a video from Photos, or send anything to DeHum through the iOS share sheet. It analyses the recording, tells you what it found, and shows you the spectrum with each harmonic marked. Tap Remove the hum, compare Original against Repaired, and export when you are convinced.

What kinds of files can I bring in?

M4A, WAV, MP3, AAC, CAF, AIFF and AIF, plus standard MP4 and MOV video. On a video, DeHum repairs the audio and puts it back without re-encoding the picture.

Do I need a connection?

No, and there is nothing for one to do. DeHum has no networking code in it at all — it works in Airplane Mode exactly as it works otherwise.

DeHum says it found no hum

Then it found no hum, and it will not change the file. Mains hum is a very specific thing — a steady tone at exactly 50 or 60 Hz with harmonics above it. A rumble, a hiss, air conditioning, wind noise and room tone are all different problems, and DeHum is not a general noise reducer.

If you are certain there is hum, tell DeHum which grid the recording was made on: Settings ▸ Mains frequency. That narrows what it looks for.

Some buzz is still there

Try the Aggressive depth and compare. Aggressive removes more, and on a low voice it can take a little body with it — which is exactly why the A/B toggle sits above it. If the buzz survives every setting, it is probably not mains hum, and no setting will make it one.

The repaired voice sounds thinner than the original

Drop to Gentle, which subtracts the hum and stops there instead of also notching whatever is still standing above the noise floor. A voice whose pitch happens to sit on a hum harmonic is the case this protects.

Which depth should I use?

Standard for almost every recording. Gentle when the voice matters more than the last of the hum. Aggressive when the hum matters more than the last of the voice. Depth is a Premium control; the free tier repairs at Standard.

The free version stops after 30 seconds

That is the free tier: the first 30 seconds, at full quality, never watermarked. Premium repairs recordings up to 60 minutes. The free export is the same fidelity as the paid one — it is simply shorter.

Where did my exported file go?

Files ▸ On My iPhone ▸ DeHum ▸ Exports. Every export is saved there as well as being offered to the share sheet, so dismissing the share sheet does not lose the file you just made.

It says there is not enough space

A repair is written out as a new file rather than over your original, and a long one is large — roughly a gigabyte per hour, plus more again if the source is a video that has to be decoded first. DeHum checks before it starts rather than failing part-way through. Free up space and try again.

Did it change my original?

No. DeHum always writes a new file and never modifies what you imported. Keep your originals anyway — no app should be the only copy of anything you care about.

I subscribed but the app still says free

Settings ▸ Restore Purchases. If it still does not appear, check that you are signed in with the same Apple Account you subscribed with.

How do I cancel?

iOS Settings ▸ your name ▸ Subscriptions ▸ DeHum ▸ Cancel Subscription. Cancelling takes effect at the end of the period you have already paid for. Deleting the app does not cancel a subscription.

Is there a trial?

The annual plan includes a 7-day free trial for new subscribers. Cancel before it ends and you are not charged. If you have used a trial for this subscription before, you are charged immediately.

Can I have a refund?

Refunds are handled by Apple, under Apple’s policies — we cannot issue them. Request one at reportaproblem.apple.com.

Where do my recordings go?

Nowhere. They stay on your device, because DeHum contains no code capable of sending them anywhere — no account, no analytics, no server. You can confirm it yourself with Airplane Mode: everything still works. See the privacy policy.

What permissions does it ask for?

Only one, and only if you ask for it: permission to save a repaired video back to your photo library. Reading a video you pick needs no permission, and DeHum does not record audio, so it never asks for your microphone.