Speaker Cleaner › Why 165 Hz
Why do speaker cleaners use 165 Hz?
Speaker cleaners use tones around 165 Hz because lower frequencies make a speaker's diaphragm travel further, pushing more air and water, while tiny phone speakers can't play much below about 150 Hz at useful volume. 165 Hz sits in the sweet spot between the two limits.
At the same loudness, a speaker's diaphragm must travel roughly four times further at 165 Hz than at 330 Hz. That extra movement is what pushes water out of the grille, and it is why speaker cleaners use low tones rather than the high frequencies some tools advertise.
The two limits
At the same loudness, halving the frequency roughly quadruples how far the diaphragm must move. That's why low tones shift water best.
| Frequency | Diaphragm travel | Can a phone speaker play it loudly? |
|---|---|---|
| 50 to 100 Hz | Very large | Barely |
| 150 to 200 Hz | Large | Yes |
| 1,000 Hz | Small | Yes |
| 8,000 Hz | Tiny | Yes |
A sweep works better than a fixed tone because every phone speaker has a slightly different resonance, the frequency at which it moves most easily. Gliding from 150 Hz to 200 Hz and back passes through that point on most models instead of relying on one frequency being right.
This is also why the tool offers an Extended profile of 120 to 400 Hz alongside the default 150 to 200 Hz sweep. A phone speaker rolls off steeply below its own resonance, so on some small speakers 165 Hz produces very little output and a slightly higher tone moves more air. Higher frequencies still are a different matter: at 8 kHz the diaphragm travels roughly 2,300 times less than at 165 Hz for the same loudness, so tools advertising 8 kHz "deep pore cleaning" for water are promising something the physics does not support.
What happened when we tried higher tones
While building the tool, Junaid Masood, who made Speaker Cleaner, tried tones up to 2 kHz on his own phone. For water, the tones around 165 Hz pushed out the most, which is what the physics on this page predicts. For dust, the wider Extended range seemed a little more helpful, so the tool keeps 165 Hz as the Water mode default and offers Extended as an option. These were informal trials on one person's phones, not the measured test described on how we test.
Why a sweep beats a single tone
Every phone speaker is slightly different, and each has a resonant frequency where it moves most easily. A sweep from 150 to 200 Hz passes through that point on most phones, instead of relying on one fixed tone. Speaker Cleaner's Water mode sweeps up and down every 4 seconds.
High frequencies such as 8 kHz, which some tools advertise, make the diaphragm move very little. They don't help remove water.
Speaker cleaners use about 165 Hz because a speaker diaphragm moves further at lower frequencies, and that movement is what pushes water out of the grille. Small phone speakers cannot reproduce much below 150 Hz at useful volume, so a 150 to 200 Hz sweep gives the most movement a phone speaker can deliver.
See it in action
Read how a speaker cleaner works or run the sweep yourself on the Speaker Cleaner home page.
The physics, in plain terms
Three relationships decide which frequency clears a speaker. None of them is controversial, and together they explain why every serious water-ejection feature uses low tones.
1. Loudness hides how far the speaker actually moves
A speaker this small radiates sound like a tiny pulsing sphere, and for a source like that the sound pressure it produces rises with the square of the frequency for a given amount of diaphragm movement. Turn that around and you get the rule that matters here: to stay equally loud, the diaphragm has to move roughly 1/f² as far as the frequency climbs. Two tones can measure the same on a meter while one moves the cone a hundred times further than the other.
2. Water is moved by travel and airflow, not by loudness
What pushes a droplet out of a grille is the air the diaphragm shoves through the holes: the distance it travels and the speed of the air it drags with it. Travel scales as 1/f² and air speed as 1/f, so both favour low frequencies. The table shows each quantity relative to 165 Hz at the same measured loudness.
| Frequency | Diaphragm travel | Air speed at the grille | What that means for water |
|---|---|---|---|
| 120 Hz | 1.9× | 1.4× | Most movement, but many phone speakers can't play it loudly |
| 150 Hz | 1.2× | 1.1× | Start of the usable band on most phones |
| 165 Hz | 1× (reference) | 1× | The working default |
| 200 Hz | 0.68× | 0.83× | Still useful; louder on small speakers |
| 400 Hz | 0.17× | 0.41× | Weak for water, but easy for a phone to play |
| 1 kHz | 0.027× | 0.17× | Effectively nothing for water |
| 8 kHz | 0.0004× | 0.02× | About 2,300× less movement than 165 Hz |
At the same loudness, a phone speaker's diaphragm travels about 1/f² as far as the frequency rises, because a small sound source radiates pressure in proportion to the square of frequency. At 8 kHz the diaphragm moves roughly 2,300 times less than at 165 Hz, which is why high-frequency tones cannot push water out of a speaker grille however loud they sound.
3. Shaking dust is a different quantity again
Dislodging a dry particle depends on acceleration rather than distance, and acceleration is the one quantity that stays roughly constant across frequency at a given loudness: the diaphragm moves far less at high frequencies, but it reverses direction far more often. That is why a high-frequency burst is at least arguable for loose dust, even though it does nothing for water, and why phones, which can play 2 to 6 kHz much louder than 165 Hz, might shake dust harder up there. It remains an argument, not a measurement, which is why the Extended profile is optional rather than the default.
4. Why repetition and holding the phone downward matter
Surface tension is what holds a droplet in a grille hole in the first place. For a hole about half a millimetre across, the pressure needed to push the water straight out in one go is in the region of 500 pascals, far more than a phone speaker produces. The tool does not beat that pressure; it works the droplet loose over hundreds of cycles while gravity pulls in the same direction. That is the real reason the instructions insist on holding the speaker downward and repeating the run, and the reason a cleaning sound sometimes fails on the first attempt and succeeds on the third.
A speaker cleaner does not overcome surface tension in a single push. Water sitting in a grille hole roughly half a millimetre wide is held by a capillary pressure of several hundred pascals, more than a phone speaker can generate. The tone works the droplet free over hundreds of oscillations, which is why the phone should be held speaker-down so gravity pulls the water the same way.
5. Why not simply go lower than 150 Hz
Because the speaker stops cooperating. A phone speaker sits in a very small sealed volume and has its own resonance, usually somewhere in the high hundreds of hertz. Below that resonance its output falls away steeply, in the region of 12 decibels per octave, and the amplifier runs out of excursion before it runs out of volume control. A 60 Hz tone would move the diaphragm beautifully in theory and produce almost nothing in practice. The usable window on a phone is roughly 120 to 400 Hz, and the default sweep sits in the strongest part of it.