Sound Level Meter – Online Measure Room Noise with Mic

This tool provides an estimated sound pressure level using your device's built-in microphone. Since microphones vary between devices and are not professionally calibrated, readings may differ from a certified SPL meter by ±5–15 dB. For precise measurements, a dedicated calibrated sound level meter is recommended. However, this tool is excellent for comparing relative noise levels and getting a general sense of your acoustic environment.

According to the World Health Organization (WHO) and OSHA guidelines:

• Below 70 dB: Safe for unlimited exposure
• 70–85 dB: Prolonged exposure may cause gradual hearing damage
• 85–100 dB: Hearing damage possible after 1–8 hours of exposure
• 100–120 dB: Damage possible within minutes
• Above 120 dB: Immediate risk of hearing injury

The tool uses the Web Audio API to capture audio from your microphone via getUserMedia(). The audio signal is routed through an AnalyserNode, which provides time-domain sample data. We compute the RMS (Root Mean Square) value of the samples and convert it to decibels using the formula: dB = 20 × log₁₀(RMS) + offset. The offset (approximately 94) maps the digital signal to an estimated sound pressure level. A smoothing algorithm is applied to reduce rapid fluctuations for a more readable display.

Microphone access is essential for this tool to function—it captures ambient sound to measure noise levels. All audio processing happens locally on your device. No audio data is recorded, stored, or transmitted anywhere. The microphone stream is used exclusively for real-time analysis and is immediately discarded when you stop measuring. Your privacy is fully protected.

10–20 dB	Rustling leaves, barely audible
20–30 dB	Whisper, quiet bedroom at night
30–40 dB	Quiet library, soft background music
40–55 dB	Refrigerator hum, moderate rainfall
55–65 dB	Normal conversation, air conditioner
65–75 dB	Vacuum cleaner, busy office, TV audio
75–85 dB	Heavy traffic, garbage disposal, alarm clock
85–95 dB	Motorcycle, power tools, shouted conversation
95–110 dB	Live concert, car horn at close range
110+ dB	Jet engine, emergency siren, threshold of pain

Yes! This tool works on iOS and Android devices through modern browsers like Safari, Chrome, and Firefox. Mobile microphones often provide decent sensitivity for noise measurement. Simply tap Start, grant microphone permission when prompted, and the meter will begin displaying real-time readings. For best results on mobile, hold your device steadily and avoid covering the microphone port.

dBA (A-weighting) filters sound to mimic human ear sensitivity, de-emphasizing low and very high frequencies. It is the standard for workplace noise assessment and environmental regulations. dBC (C-weighting) has a flatter response and is used for measuring peak sound pressure levels of impulsive noises like explosions or gunshots. This tool provides unweighted (Z-weighting / flat) measurements as an estimate. For dBA readings, a calibrated physical SPL meter is recommended.