What is Long Term Noise Monitoring?
It might sound simple, but long term noise monitoring can mean different things to different people. There is no standard definition for what long term noise monitoring is, but here is a summary that covers the basics.
I first presented this presentation at the IOA Eastern Branch meeting and wanted to share my thoughts on what classes as long term noise monitoring. I’ll also discuss where it can be most useful, what you actually need to complete long term noise monitoring and some of the key challenges you’ll face. Let’s get started.
A Definition of Long Term Noise Monitoring
Depending on who you ask, long term noise monitoring can have various meanings. There isn’t a default time period where noise monitoring switches from being short to long-term. There are, though, a number of factors that come into play to define long term noise monitoring. Here are the key points:
- Any unattended noise monitoring where you are not with the instrument during the measurement period
- A measurement period of anything from 1 day to many months and beyond
- Noise measurements associated with BS:4142, BS:5228, Section 60 + 61, ETSU-R97 etc.
What applications need Long Term Noise Monitoring?
There are many applications where long term noise monitoring is crucial to gaining the noise data you need. Without data collected over a longer period of time, you will struggle to fully assess and understand the noise levels in any given area.
Most of our customers use long term noise monitoring for assessing community noise. This is where a neighbourhood is affected by a nearby noise source (factory, construction site etc.). Some examples are:
Another key application for long term noise monitoring is airports. Airport noise is always hitting the headlines, especially with plans for new runways at some of the UK’s biggest airports.
Residents living under the flight paths of their local airport are the first to notice any changes to the noise level, with many logging complaints on a regular basis. In order to assess the impact that the flight paths have on local communities, airports carry out long term noise monitoring on an almost continual basis.
Airport noise monitoring utilises not only environmental noise monitors to capture the raw data, but also flight tracking software so that they can associate noise levels with a particular flight over any of their flight paths. This is something that is possible through our partnership with Casper, which utilises our Invictus Noise Monitor to give real-time noise data to airports.
What Do You Need for Long Term Noise Monitoring?
Carrying out long term noise monitoring isn’t as simple as leaving a sound level meter in a field and walking away. There are a number of associated accessories you’ll require in order to complete accurate, efficient and safe long-term noise measurements. Here’s what your environmental noise monitor needs:
- Class1 Sound Level Meter (or equivalent) with:
- Integrating / Statistical Levels
- Octave bands analysis
- Long battery life / external power source
- Ability to auto-calibrate
- Data logging and storage capacity
- Download capability – 3G / Lan / Wi-Fi
- Audio recording or audio triggers – so you can capture events
- What is happening now – real-time noise monitoring
- A windshield – to ensure your microphone is fully weather protected
- An Acoustic Calibrator for initial, and final, field calibration
You’ll also need something to mount it on. Most sound level meters have the capability to be attached to a tripod. You’ll need something sturdy that can withstand being left in tough environments. You should also be able to secure your tripod to prevent theft.
Challenges for Long Term Noise Monitoring
There are a number of issues you’ll need to consider before embarking on a long term noise monitoring project:
- Weather – depending on the country you’re monitoring in, you could be seeing all 4 seasons in one day (especially in the UK). You need to make sure your equipment is robust enough to withstand all weather types and that your microphone is fully protected with a dual-layered windshield
- Location – is access an issue and can you place the monitor where you need to complete an accurate measurement?
- Communication – can you connect to your monitor via 3G, Wi-Fi, Ethernet etc. to regularly download your data
- Power – is it possible to provide an external power source to keep the monitor running or can your monitor be integrated with solar panels?
- Security – is the noise monitoring equipment safe and secure. Could someone walk away with it easily or damage it?
Unfortunately, there isn’t always an easy answer to these challenges. It’s also hard to foresee any unusual circumstances. However, if you can plan around some of the common challenges you should find long term noise monitoring easier.
Keeping Data Integrity
One of the key challenges to long term noise monitoring is data integrity. You’ve position your noise monitor and you’re planning to leave it for many months. How can you be sure that the noise measurements at the end are as accurate as when it first started?
Again, there are no right or wrong answers to keep data integrity. But there are things you can do to keep measurements as accurate as possible.
- Calibrate every day – on-site or remotely if possible
- Check the clock to ensure its correct
- Check that everything is still attached and that it’s in the same position
- Check that the power is still there and that it hasn’t been tampered with
- Download data regularly so you have back-ups
It’s Over to You
So, there are some of my thoughts on what long term noise monitoring is, what you’ll need to get the job done and some of the challenges you’ll face. Now it’s your turn to put it into practice.
Need a long term noise monitor? We have purpose-designed environmental noise monitoring systems that can be tailored to your application. The Invictus Noise Monitor can be used on its own as a portable environmental noise monitor or combined with other instruments to form part of a larger, more comprehensive noise measurement and management system.
It’s also easy to use. This means it can quickly deployed at any location and can be set-up to provide a wide range of noise measurement parameters. When combined with our Noise-Hub2 software, it really does offer a complete long term noise monitoring solution.