VIRTUAL PRACTICE LAB 01

Make the
measurement count.

Noise & hearing conservation. Set up the instruments, survey the work, and decide what the evidence tells you.

Free practiceBETA testAbout 15–25 minutes

Welcome to the lab. Start by powering the sound level meter and acoustic calibrator.

YOUR FIELD NOTEBOOK

The evidence trail.

0 recorded actions

View instrument and decision log

KEEP LEARNING

From practice to the workplace.

Learn to read the report: Reading Occupational Exposure Reports: Noise is a separate guided resource with a complete fictional report, PDF and explained decisions.

This lab is a practice activity supporting HCP-001-GI · Hearing Conservation and instrument awareness for HCP-001-CON · Construction Noise. The OSHA interpretation here uses federal general-industry criteria; construction and state requirements need separate review.

It does not award course completion, a certificate, training credit or equipment authorization. Use actual manufacturer instructions and employer-supervised practice for real instruments.

Lab manual, methods & primary sources

Fictional instrument manual

Use the 94 dB, 1 kHz calibrator setting. Seat it over the microphone. With the instrument and calibrator on, adjust the pre-check to 94.0 dB and record it for each instrument. Remove the calibrator before measuring. Record the post-check before making any adjustment.

For this exercise, a pre/post difference greater than ±0.5 dB requires holding the affected results for investigation. This is a teaching acceptance rule for these fictional instruments, not a universal manufacturer tolerance or a substitute for periodic laboratory calibration.

Exposure model

The fictional worker spends 2 hours at 94 dBA, 2 at 88 dBA, 3 at 82 dBA and 1 at 75 dBA. Each task level is held constant for this simplified model. Dose = 100 × Σ(C/T), with T = 8 × 2^{(criterion − level)/exchange} hours; levels below a channel’s threshold are excluded. Eight-hour TWA = criterion + exchange × log₂(dose/100). A zero dose has no finite TWA in this model.

The three channels use: OSHA hearing conservation 90/5/80; OSHA PEL 90/5/90; NIOSH REL 85/3/80 (criterion/exchange/threshold in dB). A weighting and slow response are used. OSHA hearing-conservation inclusion is evaluated at 50% of its channel’s dose; the separate PEL channel is evaluated at 100%. NIOSH’s recommendation uses 100% of its own channel. These are different bases, not interchangeable percentages.

Area spot readings describe locations. The personal record follows the worker. No hearing-protector attenuation is subtracted. Controls, impulsive noise, uncertainty and representativeness require further assessment in real work.