Mini Sound Level Meter

I bought a Maplin Sound Level Meter to see what it could do for just £14.99. I suspected it was a ‘toy’ as it is clearly made to look and feel like a miniature professional sound level meter. Looks cost money – so I suspected the performance would be very poor. In fact I was quite wrong.

Before describing its performance – its important to note that this sound level meter reports only the ‘C’ weighed total sound level. ‘C’ weighting treats low and high frequencies equally - which you might imagine was just what you wanted do do.
However the ear is not very sensitive to low frequencies and so estimates of noise annoyance normally use the ‘A’ weighted measurement which reflects the ears insensitivity to quiet low frequency sound, sounds like distant trafic noise, air conditioning rumble etc. The Maplin unit doesnt have an A weighting option so you cant really compare the decibel sound levels it gives you with most published tables. Look for ‘dBA’ in reports of noise level, and where it just says dB it means dBA.

This meter measures only dBC. Does this matter much? Yes it can- really low frequency noise is often the strongest sound present and its annoyance or loudness value will be over estimated by this instrument by maybe 10 or even 20dBs. Having said that – the unit really does measure actual pressure sound level accuratley to the ‘C’ standard. Although environmental noise professional dont tell you this, the loudness of really loud noise is much more accurately represented by the ‘C’ measurement than the ‘A value! This instrument will give you a true dBC sound level reading which will relate to the loudness for loud sounds but will tend to over rate ordinary medium and low level sounds IF they contain low frequencies.

Now for the technical stuff. I took the meter into the labs of UCLs Ear Institute and found the calibration to be spot on from 32Hz to 10kHz. At 1kHz the reading was within +-2dB from 44 to 114dB C. A look inside revealed a surface mount pcb packed with about 10 ICs and as many trim pots – far too many for the simple function. This is clearly a multifunction circuit designed to do a lot more in other models- including an A weighted version.

You need to decide if the dBC model is what you really need - but there is no doubt that the unit does what it says it does.

Has a couple of annoying features. The light sensitive backlight comes on, even if there's enough light to be able to see the reading without it. Would much have preferred a toggle button for switching the backlight on or off as required. The auto power off function turns the device off after 10 minutes (not the 15 minutes advertised) which can be a bit of a nuisance if you get your timing wrong. The device only uses the C weighted filter, not the more commonly used A weighting. That said, when it comes to things like monitoring traffic noise, the C weighting probably provides the more accurate sense of realism. The C weighting tends to give a higher reading the A weighted filter which, from the qualitative point of view, is probably a truer reflection of what the ear can actually hear. That's a very subjective way of looking at things, I know. What one person may find loud and intrusive, another person may not. But at the end of the day, no matter how sophisticated the devices we use, we are left with the evaluation of our own perceptual experience. Overall though, a decent bit of kit for the price.

This is a very cost effective, and yet surprisingly accurate, little meter. It is fantastic that the power button is soft so the meter does not pick up any noise from depressing the button. However, the Min/Max hold button is very 'clicky' as it uses a tactile switch. This means that you cannot record a maximum sound of <60dB as the meter picks up the click. Other than that, it has a tripod mount, so hand-held noise does not interfere with the reading, and it has a display backlight that varies in intensity as the surroundings darken.

I used this for monitoring a live sound stage at a club and found that the level jumped all over the place. Ended up using the venues own meter as this was too unreliable and inaccurate. moderator note: audio is not a static signal level. live audio will range drastically from low to high db peaks. This is what the "min max hold" options are for on these sorts of level meters. Many standalone in house db meters are set to only show the max hold level (which is likely to be why the in house unit's signal did not change as drastically)

The service was excellent and prompt. Plus the technical help was spot on.