Tests, tools & research
How loud are vibrators? What a noise figure has to state to mean anything
Noise is the specification people most often give as the reason a toy stopped being used, and it is the one the industry describes with adjectives. This page explains how to read the claims, and what a figure would have to carry to be worth publishing.
A decibel on its own is not a loudness you can compare
A decibel is a ratio on a logarithmic scale, not a quantity of noise. Two consequences follow, and both are routinely ignored in this category. A rise of ten units is heard as roughly twice as loud, so the gap between a figure of 45 and a figure of 55 is not the small difference the numbers suggest. And because the scale is a ratio, the figure is meaningless until the measurement conditions are stated.
Sound pressure in free air falls by about six units each time you double the distance from the source. A toy quoted at one distance and a toy quoted at another are not in the same contest, and almost no product listing in this category states a distance at all.
Then there is weighting. The A weighting used in most consumer figures deliberately discounts low frequencies, because that is roughly how human hearing treats them at moderate levels. It is the right curve for judging annoyance in a room, and the wrong one for judging what travels through a wall, which is mostly low frequency. One toy can be the quieter of two on one curve and the louder on the other.
The five things a noise figure must state before it is worth reading
- The distance. From the surface of the toy to the microphone, in centimeters, not from somewhere in the room.
- The mounting. Hand held, laid on a table or suspended in free air. A hard surface turns the table into a soundboard and can add more noise than the difference between two models.
- The load. Running in open air is the quietest state a motor will ever be in. Under pressure against a body or a stand-in material, a motor slows, labors and changes pitch.
- The setting. Maximum is the number people quote and the lowest step is the number brands prefer. A single figure for a toy with ten steps is a choice of which story to tell.
- The ambient floor and the weighting. A reading of 40 in a room whose own floor is 38 is not a measurement of the toy. Without the room floor and the weighting curve, the figure cannot be reproduced by anybody.
The noise that gets noticed is often not the noise in the room
There are two paths out of a bedroom. Airborne sound travels through the air and through gaps, and it is what a microphone in the room records. Structure-borne sound travels through whatever the toy is touching: a mattress, a bed frame, a floor, a shared wall. Low frequencies dominate that path, and they are precisely the ones the common weighting curve discounts.
That is why a deep, low toy can read as the quieter of two in a room and still be the one heard downstairs, and why the single most effective change is usually not buying a different toy. It is breaking the contact: off the frame, onto something soft, away from the shared wall.
It also explains a complaint that looks like a contradiction. People describe toys as quiet in the shop demonstration and loud at home, because a hand in a showroom is a far better damper than a bed is.
The method results on this page will follow
A stated room, with its own floor published first
The ambient level of the room is recorded before each session and published beside every result. If the room floor is within ten units of a reading, the reading is reported as a limit rather than a value, because the room is then part of what was captured.
A fixed geometry
The toy suspended clear of any surface, the microphone at a single stated distance, the same orientation for every unit. No hand, no table, no soft furnishing anywhere in the path.
Every setting, not the extremes
Each discrete step of the motor, in order, held long enough to settle. A toy with a gentle first step and a brutal last one deserves a curve, not a headline number.
A second pass under load
The same steps with the head pressed against a stated compliant material at a stated force, because that is the state the toy is actually used in and the state in which motors change their character.
Two curves, repeats and a tolerance
Both the A weighting and an unweighted or C weighted figure, three runs per setting, several units of the same model where possible, and the instrument tolerance printed with the table. A figure with no repeat and no tolerance is an anecdote with a decimal point.
What you can do now, without an instrument
- Treat phone sound level apps as relative, not absolute. A phone microphone has automatic gain, a frequency response tuned for speech and no calibration, so its absolute figure is not a decibel reading. Comparing two toys in the same spot in the same room with the same app, however, is a genuine comparison.
- Listen for pitch, not volume. A thin, high buzz carries less through a wall but is far more irritating in the room. A low rumble is the opposite. The answer depends on who you are hiding the noise from, and the two cases pull in opposite directions.
- Decouple the toy from the furniture. A folded towel between the toy and the bed frame does more than most upgrades.
- Read owner complaints for the word that matters. Owners who describe a toy as a motor, an engine or a drill are describing low frequency structure-borne noise. Owners who say mosquito or hairdryer are describing the airborne high end.
- Discount the phrase whisper quiet entirely. It appears on listings for products with widely different behavior. It is marketing copy, not a specification, and no standard defines it.
Questions people ask
- Is a quoted figure from a manufacturer simply false?
- Usually it is not false, it is unusable. It was most likely captured in the conditions that flatter the product, with no distance, no load and no room floor stated, which means it cannot be compared with a figure from any other brand.
- Which is quieter, air pulse or vibration?
- The two make different noises rather than one being reliably quieter. Air pulse devices move air by design, so they tend to produce a breathier mid range sound, while vibration motors concentrate energy at their running frequency. Neither family is quiet as a group, and the variation within each family is larger than the gap between them.
- Will quieter mean weaker?
- Not directly, although the two are related. Noise is the energy that escaped as sound instead of reaching your body, so a well damped housing and a well matched motor can be both quieter and more effective. A toy that is quiet because its motor is feeble is a different thing entirely, and the way to tell them apart is a strength figure, which is the subject of the vibration page.
- When will there be actual figures here?
- When there is a bench and a published method, in that order. The method goes up before the first results, so the numbers can be checked and disputed rather than taken on trust.