Monday, June 24, 2013

Usefulness of a Sound Level Meter

Chances are you've seen one of those public service notices about how your hearing is extremely important and how you can't get it back. They may tell you about the dangers of loud music through your earphones, going to loud concerts, operating heavy machinery, etc. Some measurements for a bunch of common noises may even be provided.

Having read many of these articles, I seem to recall vacuum cleaners being in the 70 decibels range and "loud rock concerts" pushing over 100 db -- don't quote me on those and not sure on weighting used. But how exactly do you know how loud a specific sound is where you are standing? And what if the noise isn't on a chart?

For a long time, I just tried to compare sounds. Is it louder or softer than a vacuum cleaner? Do my ears get muffled and ring after listening to it for a long period of time? Unfortunately, the latter method isn't safe and probably means that permanent damage has already been done. That's partly when I decided to just go out and buy a Sound Pressure Level (SPL) meter. There may have also been a new stereo I was trying to calibrate involved.
RadioShack Analog SPL Meter Front
Sound Level meter
The model I got was a RadioShack analog model that was pretty popular at the time for calibrating stereo systems. It was one of the cheaper and more widely available units too. I believe it set me back around $80, but was available for way less across the border in the U.S. Other models are available for even cheaper like this digital sound level meter at Amazon. Smartphones should also have downloadable apps that turn phones into sound meters.

However, do be warned that all devices and apps have limitations and certain degrees of accuracy. I've heard of apps not responding above certain sound levels and meters being off by more than 20%. Do your research.

Also, make sure you know how to properly operate a meter. There are various settings and things to look for, which I honestly don't know much of anything about. I'm not an expert and probably use my meter improperly, which is why I try to consider all measurements with a grain of salt.
RadioShack Analog SPL Meter Side
What to do with a sound meter?
A sound meter is very useful in measuring sound -- duh. I use my SPL meter on a regular basis to measure the sound coming out of my stereo and TV on a regular basis, even when I'm not calibrating anything. When I finally got a new music player, I used it to cap off the maximum volume setting to make sure I could blast it at what I thought was a safe volume. I say "thought" because I'm not too confident about measurements taken by mashing an earphone up to the sensor on the meter.
RadioShack Analog SPL Meter Back
There was probably only one instance when I took my meter out of the house to measure the loudness of a subway ride inside the car. I don't think my measurements were encouraging because I wear earplugs when entering subway systems now. Maybe I'm a bit too self-conscious, but it seems a bit weird and geeky to have one of these in your hand. Thinking about it now though, most people probably don't know what it is. A smartphone app would come in great handy to avoid this issue.

I only wish my RadioShack meter could measure sound below 50 db and digital because that would be so much more funner. A lot of sounds in the barely audible range would be very interesting to know.

Other uses of a sound meter may be to bring it to a concert, see how loud your neighbour's music is through the walls, and whatever else you can think of that involves sound -- *cough* noise complaint.

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Wearing earplugs in theaters, subways, concerts, everywhere!