Way back in the 60s, as traffic levels spiralled out of control in New York, someone from the city’s Noise Abatement Commission stood with a microphone, a crude receiver, a phonograph and a test tone to try to objectively plot just how much louder things had become. It was one of the first sound level meters – and things have come a long way since then.
In truth, a sound or noise level meter is any device that takes acoustic decibel measurements, working on the principle that changes in air pressure can be detected and recorded with objectivity in a standardised format. Today, they are highly sophisticated, reliable and accurate, typically consisting of a microphone, a preamplifier, a signal processor and a display. They’re used across the industry spectrum by any entity wanting to monitor, measure or manage sound or noise levels – like factories, roads and rail, construction, sports, concerts, venues and so much more.
But the list of confusing jargon associated with sound level meters is almost as long as the list of different types of sound level meters out there on the market – so how can you narrow down your short-list for your particular industry, application or needs?
Start by thinking about the following:
- Integrating?
While a non-integrating noise level meter simply displays the current noise level in real time, an integrating device will also give you an average sound level value over a set period of time. So if you only need it for spot checks with fairly stable noise levels, go for the cheaper non-integrating technology. For most other occupational or environmental noise monitoring, an integrating unit is the right choice.
- Accuracy?
Most modern sound level meters worth buying will be categorised as either Class (or Type) 1 or Class 2. While Class 2 is accurate and reliable enough for most applications, those who need extreme levels of accuracy should bump up the budget and go for Class 1. It will cost more, and it’s true that Class 2 noise level meters are usually perfectly high-performing for most tasks, but if those results are ever going to be challenged, there’s no doubt Class 1 has more credibility.
- Analysis?
Specifically, we’re talking here about frequency analysis, which will give the user extra information about the frequency profile of the sound being monitored. So if, for example, you are going to use that sound level meter to determine if and how much hearing protection is required for a particular application, you should probably shop for a device with 1/1 octave band capability. Environmental noise surveys, on the other hand, will benefit from 1/3 octave band capability as it will detect tones in the noise, while the most expensive Fast Fourier Transform feature is for extreme frequency detail.
- Extras?
Next up, think about what extra features or accessories you’ll need with your noise level meter setup. Acoustic calibrators, for instance, will tell you if your meter is working correctly, a dosimeter is a smaller, wearable sound level meter, and then there are accessories like weather resistant kits for sound level meters that will be set and left.
Finally, it’s important to match your noise level meter with the necessary measuring range, the quality and style of the display, and what complexity of on-board data logging and analysis you require. But at the end of the day, there are plenty of sound and device experts out there who will be more than happy to help you make the perfect choice for your application, industry and budget.