If you have searched for this before, you have met the water eject sound: a low, slightly ugly warbling tone that people play at full volume through a wet phone. It has been passed around long enough that it has acquired a certain mystique, and a matching amount of scepticism. Both are misplaced. It is a plain sine tone, there is nothing special about any specific recording of it, and the reason it works is about as unmysterious as physics gets.
What is actually happening
A speaker is a stiff membrane on a magnet. Feed it a signal and it moves back and forth; the air in front of it gets pushed, and that pushed air is the sound you hear. Put water in front of that membrane and two things happen at once. The water blocks the air path, which is why a wet speaker sounds muffled. And the water becomes something the membrane is pushing on directly.
That second part is the whole trick. The speaker is not “vibrating the water off” in some vague way — it is physically shoving it, once per cycle, in the only direction it can go, which is out through the grille. Hold the phone with the grille facing down and gravity keeps what has been pushed out from falling back in. Apple has shipped this as a feature on the Apple Watch for years, for exactly this reason.
Why the frequency has to be low
A speaker cone trades distance against speed. Producing a low note means moving a long way, slowly. Producing a high note means moving a very short way, very fast. Water is heavy and sticky compared to air, so what shifts a droplet is the long push — a fast, tiny flutter barely disturbs it.
That is why the numbers you keep seeing cluster where they do. 165 Hz is the one that circulates most, and there is nothing sacred about 165 specifically; it is simply a value in the band where a small phone driver has both real excursion and enough acoustic output to matter. CleanWave opens on 180 Hz for the same reason. Anywhere from roughly 100 to 200 Hz is the useful territory, and the difference between two numbers inside that band is far smaller than the difference between full volume and half volume.
Volume matters more than the number
If you take one thing from this page, take this. The force moving the water is the amplitude of the membrane, and the only control you have over amplitude is volume. A perfectly chosen frequency at 50% volume does less than a mediocre one at 100%.
This is where most disappointed attempts go wrong. People play the tone through headphones by accident. They play it with a volume limiter on, or with the phone’s hearing-safety cap active, or with the media volume down while the ringer volume is up. The tone plays, nothing happens, and they conclude the method does not work. CleanWave puts a reminder on screen through the whole cycle for this exact reason.
A sweep beats a single tone
A droplet held in a corner of the cavity by surface tension has a shape, and that shape has frequencies it responds to more than others. A single fixed tone either moves it or does not. A tone that sweeps across a range will, at some point, hit something the droplet responds to.
This is why the app’s cleaning styles are not just marketing. Original holds a relentless single band. Hardstyle moves harder and hits more angles. Deep runs slower and lower and aims at whatever is furthest in. They exist because water that will not move at one frequency very often moves at another, and cycling through beats staring at a slider.
Where vibration comes in
The haptic motor produces no sound at all, so at first glance it has no business in a speaker-cleaning app. What it does is shake the whole assembly, which breaks the grip surface tension has on a droplet stuck against the mesh. A droplet that was immovable becomes a droplet the tone can push.
Sound and vibration together clear water that neither clears alone. That is why CleanWave defaults to Both rather than making you choose, and why the choice is still there: pure vibration is the right mode when you want to shake dry dust loose without filling the room with a tone, and pure sound is the right mode when the phone is in a case that damps the haptics.
What the tone cannot do
It is worth being plain about the limits, because the internet is not.
- It does not dry the inside of the phone. It clears the speaker cavity, which sits outside the sealed part of the device. If water got past the seals, no tone reaches it. That is a different problem.
- It does not remove solids. Dried salt, packed lint and sand are not liquids and do not flow. Vibration shakes some of it loose; the rest needs a soft brush.
- It does not repair anything. A speaker that crackles or buzzes at volume is describing damage. Blocked or broken tells you which one you have in about two minutes.
- It will not help earbuds. What blocks AirPods is earwax, a solid packed into a mesh, and it does not move. Cleaning earbuds is a manual job.