Day + Night
Every survey point is measured under both periods — daytime and nighttime carry separate, stricter limits after dark.
Environmental noise is one of the most common concerns in urban communities. Reliable noise monitoring provides objective data, helping authorities and organizations identify problems,
Different Areas Have Different Noise Limits
Environmental noise assessment is not based on a single fixed limit. Acceptable noise levels vary depending on land use, surrounding conditions, and the time of day. Residential, commercial, industrial, and sensitive areas may have different noise criteria.
Multiple Noise Assessment Criteria
International environmental noise evaluation follows established frameworks such as ISO 1996, which provides guidelines for measuring and assessing environmental noise based on sound levels, exposure periods, and assessment methods.
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In our customization process, we value the communication of details with our clients to ensure a thorough understanding of your needs and expectations.
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Uniquely Yours
Custom Fashion wear Manufacturer
In our customization process, we value the communication of details with our clients to ensure a thorough understanding of your needs and expectations.
view moreFrom zone classification to a defensible compliance report
A functional zone survey is only as good as its point selection, its instrument, and its consistency from one cycle to the next. Aihua instruments covers all three.
Zone Classification & Site Selection
Confirm each area's functional category and select representative monitoring points, sited away from local reflective surfaces and isolated noise sources per ISO 1996 siting guidance.
Field Survey — Day & Night Readings
Take measurements at each point with a Class 1 handheld sound level meter, following a set schedule so daytime and nighttime periods are both represented every cycle.
Data Logging & Verification
Log each reading against its point ID, timestamp, and weather conditions, and verify the instrument against a field calibrator before and after the survey run.
Compliance Reporting
Compile readings from every point into a report against each zone's daytime and nighttime limit, and flag any point that exceeds its permitted level.
ISO 1996-1
Description, measurement and assessment of environmental noise — basic quantities and assessment procedures.
ISO 1996-2
Determination of environmental noise levels, including measurement methods and site selection guidance.
WHO Environmental Noise Guidelines
Health-based reference levels for community exposure to road traffic, rail and aircraft noise.
Local / national noise ordinance
Most countries and cities set their own enforceable zone classifications and limit values — confirm the current requirement with your local environmental authority.
How is this different from workplace noise monitoring?
Workplace monitoring tracks one worker's personal dose over a single shift. Functional zone monitoring tracks a fixed outdoor location's ambient noise level against a limit that depends on how that land is zoned, measured consistently across day and night on a set schedule.
How are functional zones classified?
Most environmental authorities assign each area a category — from protected/quiet zones through residential, mixed-use, industrial, and transportation-corridor areas — based on its designated land use. The specific categories and numeric limits are set by national or local regulation and vary by country.
Why are nighttime limits stricter than daytime limits?
Ambient background noise is naturally lower at night, and disturbed sleep has an outsized impact on public health and complaints, so every zone category carries a lower permitted level after dark than during the day.
How often should a functional zone be surveyed?
LAeq is the equivalent continuous sound level over a measurement period. TWA (Time-Weighted Average) and Lex,8h both normalize exposure to a standard 8-hour workday, so results from different shift lengths can be compared against the same 85 dB(A) benchmark.
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Planning a functional zone survey program?
We look forward to hearing from you.
Tel: +86-19012832378