Skip to content
18+ only. Adults 18 and over may order, age is confirmed at checkout, and the carrier may require an adult signature at delivery.
HUSHWELL brand mark HUSHWELL
AC CT0
HUSHWELL information

How quiet is quiet? Motor noise explained

Why a decibel figure beats the word quiet

“Quiet” is a comparison with no reference point. A motor described as quiet might be rated anywhere between 28 and 55 dB(A), and both descriptions would be defensible to whoever wrote them. A decibel figure gives you something to hold: it names the unit, it implies a distance, and it lets you put two products side by side and see which one reads lower. We publish the figure for every motor on the shelf along with the setting it was taken at, because one motor can differ by eight or ten decibels between its lowest and highest speed.

The scale, in sounds you already know

Decibels are logarithmic, so the numbers behave differently from the ones on a ruler. An increase of about ten dB(A) is roughly a doubling of perceived loudness; an increase of three dB(A) is noticeable in a quiet room but not dramatic. Familiar reference points, all approximate:

  • 28 to 32 dB(A): a bedroom at night with the windows shut.
  • About 40 dB(A): a library reading room, or a refrigerator humming in a nearby kitchen.
  • About 50 dB(A): steady rain against a window.
  • 55 to 60 dB(A): ordinary conversation across a table.
  • 70 to 75 dB(A): a vacuum cleaner in the next room.

Two things follow from that list. First, moving from 33 dB(A) to 43 dB(A) is not a small step; it crosses from below the level of a fridge hum to clearly above it. Second, your room already has a noise floor. A motor rated a few decibels above that floor blends into the room, while one rated fifteen decibels above it is a distinct sound with a location, and a location is what other people notice.

Distance and surface change the number most

Sound falls away with distance, so a figure quoted without a distance is not really a figure. Our ratings are stated at one metre in still air. Listen from three metres and the same motor reads several decibels lower, though a thin partition wall can give much of that back through structure rather than air.

The bigger variable is what the motor is resting on. A hard nightstand, a wooden floorboard or a glass tabletop will pick up vibration from the handle and broadcast it, sometimes making a small motor sound larger than a bigger one on a soft surface. A folded towel, a paperback or your own hand absorbs much of that energy. In practice, changing what sits under the item does more for perceived noise than choosing between two motors a few decibels apart.

Why motors get louder over a session

Three things push a reading upward. Speed comes first: more revolutions per minute means more broadband mechanical noise, so the top setting is always the loudest. Load comes second: pressed firmly against a surface, a motor works harder and changes pitch. Wear comes third, and it is gradual: a bearing that has run without lubrication, or a shaft with lint wound around it, will whine where it used to hum.

There is also the electronic whine some controllers produce at low speed. Where a motor is driven by rapid switching, the low settings can carry a faint high tone that travels further than the mechanical hum around it. That is one reason a listing giving both the lowest and the highest figure is more useful than one that quotes a single peak number.

How to test any motor in your own room

  • Run it under a duvet or a folded blanket for ten seconds. If the sound drops sharply, most of what you hear is airborne and a soft surface will help.
  • Run it on a hard table, then on a towel. A large difference means the surface is the problem, not the motor.
  • Listen from the next room with the door closed, which is the distance that actually matters.
  • Test at the setting you will genuinely use, then one step above it, rather than only at the quietest speed.

What we will not print

No motor here is called silent, because a motor that moves is not silent; it is quiet to a stated degree at a stated distance. We do not quote a figure without saying where it was taken. We also do not argue that the lowest number is automatically the better purchase. A quieter motor is often a smaller one with a shorter run time, and the balance between size, power, runtime and noise is yours to weigh.

Reading a HUSHWELL listing

When a listing says 36 dB(A) low and 43 dB(A) high, read it as a small motor that stays out of the way at low speed and becomes clearly audible near the top. When it says 39 dB(A) low and 47 dB(A) high, read it as a larger motor with more mass behind it, which will also transmit more vibration into whatever it touches.

Contact

Questions about an order, a specification or a policy on this page go to [email protected] or +1 212 555 0142. We answer in the order messages arrive, Monday to Friday. The registered business name, postal address and any licence or tax numbers for this store must be supplied by the operator before this store accepts live orders.