Decibel Meter - Physics Demonstrations - Decibel Meter | Physics Undergraduate Labs

When demonstrating high sound levels (above 85 dB), limit exposure time. OSHA requires hearing protection for sustained exposure above 85 dB. Do not attempt to demonstrate sounds above 100 dB without appropriate hearing protection for all participants. The threshold of pain (130 dB) can cause immediate hearing damage.

Purpose

Demonstrates the logarithmic decibel scale for sound intensity. Students discover that each 10 dB increase requires a tenfold increase in intensity, providing an intuitive introduction to logarithmic measurement scales.

Extech SL130 sound level meter reading 90.8 dB as a fist pounds the table beside it, with MAX display showing 66.6 dB from an earlier measurement, set to 30-80 dB range

Same Extech SL130 meter in a quiet room reading 34.5 dB, showing background electronic hum level

Figure 1: The Extech SL130 registering 90.8 dB from a fist pounding the table. The display also shows MAX hold and an adjustable alert limit.

Figure 2: Baseline reading of 34.5 dB in an unoccupied classroom, showing the background electronic hum and HVAC noise.

Decibel Meter

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Safety Warnings

Warning: Hearing Protection Advisory

Purpose