Noise Monitoring: Surveys, Stations and Reporting
Monitoring makes the problem visible: not only the average level but the events, the time of day they happen and the trend after something is changed. This page covers how a monitoring programme is designed, the instruments, the quality controls that make the data defensible, and how the result is reported to a regulator, a client or a community.
Programme types: short-term to continuous
- Spot survey: attended measurements at several positions and times, to find the pattern and to answer a specific limit
- Continuous monitoring: an unattended station logging time history, statistics and events for days, months or the life of a project
- Event-based: counting exceedances of a threshold, with time, direction and probable source, for complaint handling and construction
- Before and after: the same positions measured before and after a change, to prove what the money bought
Where a site needs the station but not the instrument purchase, Geonoise provides noise monitoring as a service.
Instruments: sound level meters, dosimeters, online stations
- Class 1 sound level meter to IEC 61672-1 for attended surveys: dBA/dBC/dBZ, Fast/Slow, Leq, Lmax and statistics
- Personal dosimeters for workplace dose and TWA
- Online stations: a Class 1 outdoor microphone, logger and modem, with automatic upload, dashboard and alerts
- Calibrator: field check before and after, deviation recorded; laboratory calibration on a fixed cycle by an ISO/IEC 17025 accredited laboratory
Software and noise maps
Measured data feeds a calculation model such as SoundPLAN, which turns a few positions into a map, tests options before they are built, and gives management and the community a picture rather than a table.
- Noise contours and risk zoning around a site
- What-if scenarios: a barrier here, a truck route moved, a plant item replaced
- Spatial KPIs: complaint locations, exceedance events and traffic routes on one map
Data quality and uncertainty
- Calibration before and after, drift checked, weather logged
- Validity rules: wind, rain and equipment faults flagged and excluded with a reason
- Uncertainty estimated from instrument class, position, period and conditions
- Backup and an edit log, so the dataset can be re-examined by the other party
KPIs, dashboards and alerts
- Recommended KPIs: Leq per period, event Lmax, number of exceedances, before/after trend
- Automatic alerts on exceedance by SMS, email or LINE, with position and time
- Management dashboard: status and risk cards, the map, weekly and monthly trends
What a monitoring programme typically shows
| Setting | Measure | Illustrative result |
|---|---|---|
| City night-time noise | Continuous stations plus local barriers | A measurable fall in complaints once events are logged and answered |
| Factory | Enclosures, damping and base isolation | Event Lmax down by several decibels at the boundary |
| Office building | Sealing, added mass, resilient channels | Partition DnT,w up by 8–12; reverberation and NC to target |
These are illustrative of the kind of change a programme makes visible; the figures for any site come from its own before/after measurements. Published jobs with numbers are in case studies.
Reporting and stakeholder communication
- Weekly or monthly reports: KPI summary, heat map, peak events, practical recommendations
- Review meetings with management or the community: mitigation plan and schedule review
- Reference documents: method, instruments and calibration, QA/QC, time history and spectra, noise map
What a Geonoise report contains, and why each part is there, is set out on what a measurement report contains.
Frequently asked questions
Is continuous monitoring always necessary?
No. If the noise is steady, an attended survey answers the question. Continuous monitoring is justified when events matter, when they are frequent or unpredictable, or when a permit or EIA condition requires it.
How do I know a measure was worth the money?
By comparing before and after at the same positions: decibels, number of exceedances, complaints and disturbed hours, set against the cost.
Do I need spectral analysis?
When the problem is low frequency or tonal, yes — the spectrum decides whether the answer is mass, decoupling or a silencer. For a simple dBA limit check it is not required.
Can monitoring data be used as evidence?
Yes, when it comes from a Class 1 instrument with a current calibration certificate, follows the Pollution Control Department's method, and the QA/QC record shows which data were excluded and why. That is the standard Geonoise reports are written to.