--- title: "Environmental Noise Monitoring Systems | Aethair" description: "Continuous environmental and occupational noise monitoring: sound pressure level, equivalent continuous level (Leq), statistical levels (Ln) for community…" url: https://aethair.io/solutions/noise/ --- Aethair solutions # Noise Monitoring Environmental and occupational sound levels Continuous environmental and occupational noise monitoring: sound pressure level, equivalent continuous level (Leq), statistical levels (Ln) for community noise assessment, peak and max levels, and TWA noise dose for hearing-conservation programs, measured with IEC 61672-class instruments. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Build a Configuration](https://aethair.io/build/?params=sound_leq,sound_spl,sound_ln\&solution=noise) At a glance 3 core parameters [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) 2 devices cover it - **Thiamis** Cirrus Research Noise Monitors 2 standards set limits - [OSHA Occupational Noise Exposure (OSHA / NIOSH)](https://aethair.io/standards/occupational_noise/) - [WHO WHO Environmental Noise Guidelines for the European Region (2018)](https://aethair.io/standards/who_noise_2018/) Why it matters ## Why Noise Monitoring Matters 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. What to measure ## What to Measure and the Limits That Apply The core panel covers the main program. Other parameters are added for a specific site or requirement. Every limit below is the published value from the standard that sets it. 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. Equivalent Continuous Level (Leq) Noise [**53 dB** *Lden, road traffic* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**45 dB** *Lnight, road traffic* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**54 dB** *Lden, railway* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**44 dB** *Lnight, railway* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**45 dB** *Lden, aircraft* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**40 dB** *Lnight, aircraft* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/) [**45 dB** *Lden, wind turbines* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/ "conditional recommendation") [**70 dB** *LAeq,24h yearly average, leisure noise* · WHO noise 2018](https://aethair.io/standards/who_noise_2018/ "all leisure sources combined") Environmental noise assessment, whether for planning, industry, transport, or entertainment venues, is built on the equivalent continuous level (Leq) measured against limits at the affected receptor. Continuous, weatherproofed Leq monitoring with an IEC 61672 instrument captures the fluctuating real-world sound over days or weeks, providing the defensible record that resolves complaints and demonstrates compliance. - **WHO noise 2018** 45 dB: conditional recommendation - **WHO noise 2018** 70 dB: all leisure sources combined [Equivalent Continuous Level (Leq): sensors, units, and every standard](https://aethair.io/parameters/sound_leq/) Sound Pressure Level (SPL) Noise Sound pressure level is the fundamental decibel measurement underlying all noise assessment, the instantaneous level from which Leq and the other metrics are derived. Continuous SPL monitoring with an IEC 61672 instrument is the starting point for environmental and occupational noise work, capturing the raw acoustic level from which the summary metrics are calculated. [Sound Pressure Level (SPL): sensors, units, and every standard](https://aethair.io/parameters/sound_spl/) Statistical Level (Ln) Noise Statistical noise levels (Ln) describe how noise is distributed over time: L90 characterizes the background and L10 the intrusive peaks. That makes them essential to community and environmental noise assessment. Continuous Ln monitoring with an IEC 61672 instrument reveals the character of a noise climate that a single average level would hide, and underpins many planning and nuisance criteria. [Statistical Level (Ln): sensors, units, and every standard](https://aethair.io/parameters/sound_ln/) Max Level (Lmax) Often added · Noise Maximum sound level over the interval. [Max Level (Lmax): sensors, units, and every standard](https://aethair.io/parameters/sound_lmax/) Min Level (Lmin) Often added · Noise Minimum sound level over the interval. [Min Level (Lmin): sensors, units, and every standard](https://aethair.io/parameters/sound_lmin/) Peak Level (Lpeak) Often added · Noise [**140 dBC** *Impulse peak (OSHA ceiling)* · OSHA / NIOSH noise](https://aethair.io/standards/occupational_noise/) Peak sound pressure level (C-weighted peak used for impulse-noise limits). [Peak Level (Lpeak): sensors, units, and every standard](https://aethair.io/parameters/sound_lpeak/) TWA / Noise Dose Often added · Noise [**90 dBA** *8-hour TWA (OSHA PEL)* · OSHA / NIOSH noise](https://aethair.io/standards/occupational_noise/ "5 dB exchange rate") [**85 dBA** *8-hour TWA (OSHA action level)* · OSHA / NIOSH noise](https://aethair.io/standards/occupational_noise/ "5 dB exchange rate") [**85 dBA** *8-hour TWA (NIOSH REL)* · OSHA / NIOSH noise](https://aethair.io/standards/occupational_noise/ "3 dB exchange rate") Time-weighted average / noise dose over the work shift. - **OSHA / NIOSH noise** 90 dBA: 5 dB exchange rate - **OSHA / NIOSH noise** 85 dBA: 5 dB exchange rate - **OSHA / NIOSH noise** 85 dBA: 3 dB exchange rate [TWA / Noise Dose: sensors, units, and every standard](https://aethair.io/parameters/sound_twa/) **Methods and guidance:** [IEC 61672: sound level meters (Class 1/2)](https://aethair.io/standards/iec_61672/) [IEC 61260-1: octave-band and fractional-octave-band filters](https://aethair.io/standards/iec_61260/) The setup ## How a Monitoring Setup Works 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. [Customize this configuration](https://aethair.io/build/?params=sound_leq,sound_spl,sound_ln\&solution=noise) Which monitor ## The Instruments in This Configuration A [Thiamis](https://aethair.io/products/thiamis/) gateway logs these instruments continuously and sends their readings to Environet over 4G LTE (cellular data included) or the site's Wi-Fi. There they get the same alerts, reports, dashboards, and API as any Aethair monitor, in one account with every other device on the site, instead of a separate vendor app for each instrument. Thiamis runs on mains power, a solar panel, or an external battery. ### [Cirrus Research Noise Monitors](https://aethair.io/sensors/cirrus-research-noise-monitors/) Cirrus Research Optimus and Optimus+ handheld sound level meters are integrating, data-logging instruments that measure SPL, Leq, Peak, and statistical Ln to IEC 61672 Class 1 or Class 2. [How Thiamis connects them](https://aethair.io/products/thiamis/) What you get ## Readings, Alerts, and the Report That Proves It Every reading goes to the Aethair platform. Here is what a monitoring program gets from it. ### [Live data and alerts](https://aethair.io/platform/environet/) Every reading in Environet as it happens, with alerts by email, SMS, or webhook at the thresholds you set. ### [Compliance reports](https://aethair.io/platform/reports/) Scheduled or on-demand reports against the standards above or your own limits, as PDF or a secure link. ### [Dashboards and AI analysis](https://aethair.io/platform/dashboards/) Live displays for a site or the public, and Noesis answering questions about the data in plain language. ### [Your data, through the API](https://docs.environet.io/) Live and historical readings as JSON or CSV through the Environet API (OpenAPI 3.2), for a building management system, an ERP, or your own applications. The data is yours. [See a sample report](https://aethair.io/docs/aethair-hq-first-floor-report-example.pdf) Article Library ## Reading for Noise Monitoring ### [Air Quality Near Data Centers: What Communities Should Know](https://aethair.io/resources/air-quality-near-data-centers/) Air quality near data centers: construction dust, diesel generator emissions, and noise, and how communities get independent monitoring data. ### [Data Center Air Quality Monitoring, Inside and Out](https://aethair.io/resources/data-center-air-quality-monitoring/) Data center air quality monitoring for operators: ISO 14644 cleanliness in the white space, construction dust, generator emissions, and perimeter noise. [All articles](https://aethair.io/resources/) Related solutions ## Related Solutions ### [Perimeter Monitoring](https://aethair.io/solutions/perimeter-monitoring/) Site boundary dust, silica, and noise compliance ### [Cabin Air Quality](https://aethair.io/solutions/cabin-air/) Respirable dust, gases, and blast monitoring ### [Occupational Safety & Industrial Hygiene](https://aethair.io/solutions/occupational-safety/) Worker exposure, confined space, and heat stress [All solutions](https://aethair.io/solutions/) Questions ## Noise Monitoring FAQ What is the difference between SPL and Leq? Sound pressure level is the instantaneous sound level at a given moment, while Leq is the equivalent continuous level: the single steady value that carries the same energy as the fluctuating real sound over a period. Most noise limits are written in terms of Leq because it summarizes varying noise into one comparable figure. Why are statistical levels and Lmax measured? Statistical levels such as the background and typical levels describe how noise varies over time, which matters for judging the character of a noise climate and its intrusion on a quiet period. Lmax and Lpeak capture the loudest events and sharp impulses, which drive both annoyance and the risk of hearing damage, so they complement the averaged Leq. What does IEC 61672 mean for noise monitoring? IEC 61672 is the international standard defining the performance of sound-level meters, including their accuracy classes. Using an instrument that meets it ensures noise measurements are valid, comparable, and accepted for compliance, which is why environmental and occupational monitoring specify compliant meters. What levels apply to community noise? Community noise is judged against local ordinances and guidelines rather than the workplace limit on this page: the WHO Environmental Noise Guidelines (2018) recommend road-traffic noise below 53 dB Lden and 45 dB at night (Lnight), and city ordinances set boundary limits by zone and time of day. Where a permit or ordinance calls for a Class 1 or Class 2 sound level meter to IEC 61672, connect one through Thiamis; the Aethair PRO's built-in sound level carries no IEC 61672 class on its spec sheet, so use it for alerts and trends. What is the best setup for noise monitoring? A Thiamis gateway connected to an IEC 61672 sound-level meter reporting SPL, Leq, statistical levels, and peaks continuously, with weatherproofing and wind data for outdoor deployments and worker-position measurement for occupational dose. Use the configurator to assemble the meter, weather sensors, and positions your survey needs.