Sound-Level Meter Settings And Instrument Limits
Canonical Definition
Sound-level meter settings are the frequency weighting, time weighting or integration, peak detector, range, threshold, exchange rate, criterion, microphone, calibration, and spatial setup that determine what a reported level means. The entire chain must remain within its linear range.
Weighting
| Setting | Typical question | Do not assume |
|---|---|---|
| A weighting | occupational or recreational exposure and many environmental comparisons | that it describes extreme low-frequency pressure, structure, or equipment stress |
| C weighting | broad high-level content, low-frequency contribution, and some peak or venue comparisons | that every competition or safety rule uses it |
| Z weighting | substantially unweighted pressure within the instrument bandwidth | that the microphone and preamplifier remain flat or unclipped at every level |
Detector And Integration
- Slow or Fast: time-weighted displays of changing level.
- Leq: energy-equivalent level over a stated interval.
- Maximum: highest value produced by the selected weighting and detector.
- True peak: largest instantaneous pressure captured by a sufficiently fast and unclipped path.
- Dose or TWA: time-integrated result under a declared exposure model.
Peak hold, maximum, and true peak are not synonyms.
Calibration And Range
- Verify the microphone, preamplifier, meter, sensor, and acquisition range for the expected level and bandwidth.
- Perform a documented pre-use calibration check.
- Set weighting, detector, range, threshold, exchange rate, and logging before entering the controlled zone.
- Use remote logging or viewing during hazardous runs.
- Perform a post-use calibration check and flag drift, overload, clipping, or missing data.
Phone Apps And Competition Sensors
A phone app can be useful for screening or education, but its accuracy, microphone range, processing, calibration, and overload behavior must be known. The NIOSH SLM app has been laboratory verified for supported iOS hardware; that does not make every phone or app a regulatory or extreme-level instrument.
A competition sensor is valid for the event rule and placement it was designed to measure. It is not automatically an ear-position dosimeter or true-peak hearing-risk instrument.
Overload Is A Failed Measurement
Replace the microphone, preamplifier, range, sensor, or acquisition path before using the result for exposure or safety decisions.