Norsonic offers a wide range of solutions for Environmental Noise Monitoring. From stand-alone Noise Monitoring Terminals (NMT) with local or remote access. To large scaled hosted systems with several NMTs, fully automated which deliver daily reports with noise data and meteorological data to the customer.
When our customers contacts us about Environmental Monitoring we first define their needs and requirements. Then we suggest a solution based on this. When the customer is satisfied with our proposal, we implement the solution.
Throughout the world on every continent, we have delivered solutions for Environmental Noise monitoring. We have systems at harbours, construction sites, traffic noise monitoring, wind energy plants, racetracks, production plants, shooting ranges and airports. Some systems are ran by the customer itself. However, more and more customers choose to let Norsonic host their systems. Then they can focus on their main task and key knowledge; analysing the data from the Noise Monitoring Terminals,while we take care of the “boring stuff” like communication, configuration, backup, report generators ++.
Examples of solutions that we have delivered:
- Shoeburyness Shooting Range, UK – 7 NMTs with central server at control central.
- Risavika Havn, Norway. Busy harbour area, 5 NMTs with hosted server at Norsonic main office Tranby, Norway
- Goodwood Race Circuit, UK, 3 NMTs with central server at race control. Automated daily reporting.
- Stockholm City, Sweden. Monitoring of construction noise. 3 NMTs with hosted server at Norsonic main office Tranby, Norway
- Patna, Bihar Province, India. Monitoring of traffic and industrial noise in the city. 5 NMTs with central server at the Environmental Department Office.
In a noise measurement system with multiple terminals, the noise data are streamed to a cloud based server. The data are being analysed and from the server, your results can be presented in web browser. Do you wish to give people access to the measurement results it can be local authorities or acoustic consultants, time profile graphs can be made accessible for anyone through the cloud service.
For those responsible of noise polluting activities, it is often of high interest to get an immediate warning when sound levels are too high. For example will the sound technician on an outdoor concert be able to reduce the volume directly if he gets a warning from a noise monitoring terminal that noise level at neighbours’ premises exceeds the local limitations. Such a warning can be sent as email or SMS with information about location, duration and of course the measured sound level.
In order to securely identify what actually caused the noise, advanced systems have triggers that can start recording of audio, video or both. These can then be streamed remotely near to real time for immediate identification of the source, or they can be replayed later during post-processing of the data. Video recording can be very efficient to later prove what caused the noise, be it a person, a vehicle or other.
Do you wish to have a custom made report summarizing all events the last 24 hours? A cloud based service can provide automated daily, weekly, monthly or annual reports for one or several noise monitoring terminals. Download of reports can be done manually, or if you prefer the report can be sent to your inbox. Then the report is waiting for you when you log on to your computer the next morning!
The reports can be designed to meet the requirements of you or the contracting entity.
Of course you can also log in to the cloud service and make your own ad-hoc reports!
For the specialist, advanced post processing software makes further analyses possible: Automatic selection of specific noise patterns and recalculation of average levels of different time lengths can be done. Date logged during certain weather conditions can be discarded. If sound files are recorded an FFT analysis for pure tone detection can be performed, this is a typical application for noise monitoring from wind power farms.
There are a number of national and international standards that recommend how noise from different sources shall be characterized through measurements. Traffic noise, railway noise, airport noise and wind power plants all have their own standards (see examples in the table below). The standards usually describe in detail how the measurements shall be carried out and under what meteorological conditions.
International standards for measuring environmental noise
ISO 1996 – Description, Measurement and Assessment of Environmental Noise
ISO 3891– Procedure for describing aircraft noise heard on the ground
ISO/DIS 20906 – Acoustics – Unattended monitoring of aircraft sound in the vicinity of airports (standard in preparation)
ISO 3095 – Railway applications –Acoustics – Measurement of noise emitted by railbound vehicles
IEC 61400-11 Amendment 1 – Wind turbine generator systems – Part 11: Acoustic noise measurement techniques
Noise Monitoring Terminal (NMT) is a wide expression. In its simplest form it can be a handheld sound level placed permanently or semi permanently to record the noise in a dry environment e.g. in an office. In a more advanced system, the sound level meter can be capsuled in a weatherproof cabinet with a communication device and battery backup. Where the microphone is protected in an outdoor capsule, which are designed and tested in harsh environment.
The noise monitoring terminal is the piece of equipment that acquires sound level and other data and transmits it to the server. It comprises the sound level measurement apparatus (microphone, power supply, sound level meter) along with an enclosure, a communication device and possibly a weather station and camera.
The bases for a noise monitoring station are the microphone and the sound level measurement device. In order to be certain that your measurements are of the highest quality, the sound level meter should be approved to satisfy the standard IEC 61672:2003 “Electroacoustics – sound level meters” by a national institution such as PTB (the German national metrology institute). An approved meter is tested to give correct results under varying physical conditions. The standard defines the precision of two categories of meters: Class 1 and Class 2. A Class 1 meter is required for noise measurements in most countries.
Microphones for permanent outdoor installations must be designed to withstand variations in temperature and humidity, and also resist heavy rain and corrosive climate. They should have a self-check functionality using an electrostatic actuator or a charge injection method. This way the microphones can be automatically verified so that the interval for manual inspection of the terminals can be prolonged.
The noise monitoring terminal should be robustly designed with battery backup, tamper proof enclosure and proper temperature regulation to secure stable long term logging of noise data. It should also have a self-monitoring function so that the status of the terminal (such as external power and battery status etc.) is logged and can be verified by the operator.
The communication revolution with broadband data traffic has opened for a new world of noise monitoring. Some years ago, the most advanced systems would only allow transmission of small amounts of data. Now, transmission capacity has increased and communication prices have decreased. This means that higher resolution results can be transmitted and even sound recordings and video images may be streamed close to real time. State of the art noise monitoring terminals support all modern communication platforms such as LAN, WLAN, UMTS and LTE.