Measuring Sound – is an App as Good as a Sound Level Meter?
Let’s face it, nowadays there’s an App for everything. From ordering a pizza to medical diagnostics, many of us needn’t leave the house – or our place of work – if we need something from the outside world. But when it comes to assessing noise levels, just how good are free sound level meter Apps, and can they ever replace professional sound level meters? In this post, we’ll look at the drawbacks and limitations of relying on a smartphone to monitor noise levels, and why it’s important to invest in the best equipment possible.
Measuring Sound using Smartphone Apps
Given that in the US alone over 70% of people use smartphones, it makes sense that people who are interested in noise exposure would like to utilise an App. This could be for a number of reasons – concern about working in a noisy environment or the stress of living close to a construction site, for example. There are a number of good sound measurement Apps out there, available on both Apple iOS and Google Android platforms. Here are some of the best:
This is one of the few noise measuring Apps that’s pre-calibrated and supports dBA and dBC measurement. Available on iOS and Android platforms, this App is the ultimate in portability and the results can easily be saved for future analysis and shared across social media platforms.
Sound Meter and Noise Detector
This Android App is excellent for recording and graphing sound, and as it runs in the background you can save on battery life. However, the only drawback with this App is the in-App advertising which can be a bit overwhelming and troublesome to navigate!
Sound Meter Pro
Although not a free App, sometimes it’s worth a small spend to acquire an App that’s free of advertising. This App is constantly being tweaked and improved, and also has an excellent accompanying Blog that the developers use to update users of improvements.
However, while good at giving an indication of noise levels, the readings provided via smartphone Apps do not meet the accuracy required by international governing bodies for the following reasons:
1. Smartphones rely on input from an internal microphone. Some internal microphones are limited to detect 30-96dB, to be compatible with the range of a human voice (during a normal conversation, we speak at between 40-65 dB).
2. Microphones in smartphones are designed to limit external noise; this noise cancelling function is excellent for making calls but not so great for detecting noise.
3. While the Apps are pre calibrated, you’ll need to use an external microphone and ensure you’ve calibrated your phone using a professional sound meter to get anywhere near accurate results.
4. People tend to hold the phone with the microphone positioned towards them, rather than in the direction of the sound; or place them on a surface, which also hinders sound input.
5. In order to meet international standards, sound meters need to meet IEC Class 1 or Class 2 standards, something that smartphones clearly don’t do.
6. The sheer range of smartphones - as well as Apps – on the market means that there’s a serious variation and margin of error in readings given.
All of these factors mean that while sound meter Apps are great for giving an indication of noise levels, they can’t be relied upon for exact sound levels; furthermore, they have no legal standing so can’t be used to support noise complaints. They are good, however, for measuring exposure times and for a quick spot check to give an idea of whether ear protection is required, if a professional sound level meter isn’t available.
Sound Level Meters – Cheap versus Professional
When it comes to choosing a sound level meter, there’s a vast range out there. A cursory search on Amazon will show that you can pick one up for under £10. However, the old saying ‘you get what you pay for’ definitely springs to mind here. In fact, cheap sound level meters face the same limitations as Apps – poor microphones, inaccurate calibration and unreliable recording equipment.
It’s important to bear in mind how imperative it is to take an accurate reading – it could make the difference between someone suffering permanent hearing loss in the workplace or whether noise levels are having a serious impact on the health and wellbeing of those around a construction site. Remember that the decibel scale is logarithmic, and from 0 dB (the quietest sound a human ear can detect) every 3 dB increase actually represents a doubling of sound intensity. So the fact that you take a reading of 27dB instead of 24 dB isn’t a difference in magnitude of 3 units, it’s actually twice as loud.
How to Choose the Best
Professional sound meters are hand-held devices and consist of an external microphone attached to a diaphragm that responds to changes in air pressure caused by the sound waves recorded. If you’re looking to invest in a sound level meter, then you’ll need to make sure that it meets your needs in terms of portability and pricing. The meter must also meet the functionality and performance standards as specified by the International Electrotechnical Commission. The Commission sets out both Class 1 and Class 2 standards, with Class 1 being the more accurate. The most current standard is IEC 61672-1:2013. This sets out the following minimum measuring requirements:
· Equivalent continuous A-weighted sound levels (A weighting represents sounds human ears can detect). This is known as dBA or LAeq.
· Maximum C-weighted pressure levels (C weighting represents loud noises we hear, those above 100 dB). This is known as dBC or LCpeak.
However, the costs of these professional sound meters can run into the thousands, which makes their use prohibitive to the general public. So rather than buy a cheap meter that doesn’t meet minimum standards, it’s probably better policy to use a good App, but be wary of the limitations posed by the phone itself, the position of the microphone when recording and just use the reading as a general idea of the noise level and duration of exposure.
Given the devastating impact that noise can have on the immediate environment, and the cost of investing in and ensuring that sound meters remain compliant with regulations, the majority of professionals turn to the services of an Acoustic Consultant. Whether it be a one-off assessment or a compliance test, or even monitoring and advising on large-scale construction projects, a good Acoustic Consultant will only use the latest equipment to ensure the most accurate recordings are taken and reported. Get in touch with our team at Auricl and see how we can guide you through your acoustic journey. You can contact our London office contact on 020 7859 4530; for the Reading office dial 0118 207 7324. Or you can email us on firstname.lastname@example.org.