Noise Monitoring

Sound becomes a problem in two distinct settings, and both rely on measurement to manage it. In the environment, noise from construction, industry, transportation, and entertainment disturbs communities and is controlled through permit conditions and local ordinances that a site must be shown to meet at nearby receptors. In the workplace, sustained high sound levels damage hearing permanently, and occupational-health law requires employers to assess exposure and protect workers. In both cases the obligation is to prove compliance, not merely to claim it, and that requires instruments and metrics defined by standards rather than a subjective impression of loudness.

Continuous monitoring turns noise from a matter of complaint and dispute into measured evidence. It warns when a limit is approached and documents conditions over the hours, days, and weeks the limits cover.

The base quantity is sound pressure level (SPL), but noise is characterized through several derived metrics because loudness alone does not capture its impact. Leq, the equivalent continuous level, averages fluctuating sound into a single figure and is the metric most limits are written around. Statistical levels (Ln) such as the background and typical levels describe how noise is distributed over time, while Lmax and Lpeak capture the loudest events and the impulses that matter for both annoyance and hearing damage. For workers, TWA dose (the time-weighted average exposure across a shift) is the occupational measure. Measurements are made with instruments meeting the IEC 61672 sound-level-meter standard, with frequency weighting so the result reflects how people hear.

Environmental and occupational noise measurement requires a sound-level meter that meets IEC 61672, so the metrics are valid and defensible. The recommended configuration below is a Cirrus Research Optimus+ Environmental (Green) meter, Class 1 or Class 2 to IEC 61672, on a Thiamis gateway. Thiamis logs its SPL, Leq, statistical, and peak metrics continuously and sends them to Environet, where dashboards and alerts warn when a level approaches a limit. The Optimus is a handheld meter, so a long-term outdoor position needs an outdoor microphone kit and a weatherproof enclosure for the meter and the gateway. For occupational assessment, the measurement targets the worker's position to build the time-weighted dose. Wind and weather data alongside outdoor noise help distinguish genuine source noise from wind-affected readings. Use the configurator to add a weather station or extra positions for your survey.