Why does my iPhone recording buzz or hum while charging?

This one earns its own explanation because it looks like a recording problem and behaves like one — a bad sound sitting in the file — while actually starting somewhere the recording app has no visibility into at all: the electrical path between the wall and the phone.

What the noise actually is

Chargers do not send a phone a smooth trickle of power. Most modern ones — especially fast chargers — convert mains electricity by switching it on and off many thousands of times a second, which is efficient but also generates a small amount of electrical noise at those switching frequencies. Ordinarily that noise stays inside the charging circuit. It becomes audible when some of it leaks into a nearby signal path instead, and a microphone input, carrying a very small voltage to begin with, is exactly the kind of path that picks up a little leakage as an audible hum or buzz sitting underneath everything else in the recording.

This is not unique to iPhones or to any one recorder app. It shows up on laptops, on other phones, and on dedicated recording equipment too, whenever a switching power supply and a microphone circuit end up close together and the shielding between them is not quite enough.

Why it is worse with some chargers and cables than others

The amount of noise that actually leaks through depends on the electronics inside the specific charger and how well the cable is shielded — not on how new or expensive either one looks. A cheap or uncertified adapter, a very compact fast charger, or a worn cable with damaged shielding are the usual culprits, because they were built with looser tolerances around exactly this kind of leakage. A wireless charging pad can cause the same thing for a different reason: it is generating a fluctuating magnetic field right underneath the phone the entire time it is charging, and that field can couple into the same circuits.

None of this means a specific charger is broken or unsafe — plenty of chargers that work perfectly well for charging still leak enough electrical noise to be audible to a sensitive microphone input, because charging and clean audio were never the same design goal.

Confirming that is actually what you are hearing

The test costs nothing and takes thirty seconds: unplug the cable, record ten seconds in the same spot, and compare it to a clip made while plugged in. If the buzz is present only when charging and absent the moment the cable comes out, the charger is the source, not the room, the microphone, or the app. If the noise is there either way, it is a different problem — likely the kind of steady background noise a fan or an appliance produces, which has its own separate set of causes and fixes.

What actually fixes it

• Unplug before you record. This is the reliable fix, not a workaround — if the phone has enough charge for the length of the recording, there is no electrical noise to leak in the first place.
• If you genuinely need to stay plugged in for a long session, try a different cable and adapter. Since the leakage depends on the specific hardware, swapping either one sometimes removes the noise entirely even though nothing else about the setup changed.
• Move the phone further from the cable and adapter rather than having them resting against each other. A little physical distance between the phone and the charging hardware reduces how much noise couples in, the same way distance helps with any interference.
• Avoid a wireless charging pad for anything you are recording on, since the pad itself is generating the interference the whole time the phone sits on it.

What does not fix it

The recording quality setting has nothing to do with this. Standard, high and ultra change how finely the microphone signal is sampled over time — they do not change what electrical noise reached the input before sampling ever happened, so a buzz picked up at standard quality is picked up identically at ultra. It is also not something that shows up because a phone is old or a battery is degraded; it is purely about what is on the other end of the cable at the moment you press record.

Once it is already in a recording

A steady hum sitting underneath a voice, unlike a clipped peak, is the kind of noise that processing after the fact can genuinely reduce, because it is a narrow, constant layer rather than information the microphone never captured in the first place. It will rarely disappear completely, and the far more reliable fix is not letting it in to begin with — the same way it is easier to record in a quiet room than to remove a fan afterwards.

How Voice Studio fits in

Voice Studio does not put a manual input stage in front of you to work around this, and it has no way to tell the difference between a charger's electrical noise and any other steady background sound — both just arrive as part of what the microphone picked up. Noise reduction, part of Pro alongside live monitoring, targets exactly this kind of constant, low-level noise sitting under a voice, and live monitoring lets you hear a charging buzz while it is happening rather than discovering it afterwards. Either way, the setting worth checking first is not in the app at all — it is whether the cable is still in.

Common questions

Does a higher quality setting cause or fix the buzzing?

Neither. Standard, high and ultra change the sample rate the recording is captured at, not what electrical noise reached the microphone input before that. The buzz is identical at every quality tier.

Does wireless charging cause the same problem as a cable?

It can, for a related reason — a wireless charging pad generates a fluctuating magnetic field under the phone the whole time it is charging, and that field can couple into the same circuits a cable's electrical noise would.

Will noise reduction remove a hum that is already in a recording?

It can meaningfully reduce it, because a steady hum is a narrow, constant layer rather than a clipped or missing part of the signal. It rarely disappears completely, so preventing it by unplugging is still the more reliable fix.

Is a charger that causes this noise unsafe or faulty?

Not necessarily. Plenty of chargers that work fine for charging still leak enough electrical noise to be audible to a sensitive microphone input, because quiet audio was never part of what a charger is built to guarantee.