dB
What is dB?
The decibel (dB) is a logarithmic unit used to measure sound intensity. An increase of 10 dB represents a tenfold increase in sound intensity, and a doubling of perceived loudness.
Learn
Understanding Sound Levels
DecibelMeter helps you understand and measure sound levels in your environment. The decibel (dB) scale is logarithmic — small numerical changes represent large differences in sound pressure. This guide explains how to interpret sound measurements, understand acoustic weighting functions, and protect your hearing from harmful exposure levels. Whether you're an audio professional, work in a noisy environment, or are simply curious about sound measurement, you'll find clear explanations of the key metrics, weighting curves, and safety thresholds that matter most.
The Decibel Scale
Logarithmic (dB)Values are approximate for reference only. Sound pressure doubles every 6 dB; perceived loudness doubles every ~10 dB.
0–20 dB
Barely audible (Leaves rustling)
20–40 dB
Quiet — whisper, library
40–60 dB
Moderate — conversation
60–80 dB
Loud — busy street, office
80–100 dB
Very loud — power tools (Caution)
100–120 dB
Extremely loud — concert, siren
120+ dB
Pain threshold (Immediate damage)
10 dB
10× sound intensity
6 dB
2× sound pressure
10 dB
2× perceived loudness
Acoustic Fundamentals & Metrics
6 Key MetricsSix concepts that explain what the numbers on your meter actually mean — from raw pressure to the way the ear hears it.
dBA
What is dBA?
A-weighted decibels (dBA) adjust measurements to match how the human ear perceives different frequencies. The standard worldwide for environmental noise and occupational exposure limits.
Leq
What is Leq?
Equivalent Continuous Sound Level — the average sound energy over an entire measurement duration. It is the gold-standard metric for assessing cumulative hearing risk.
RMS
What is RMS?
Root Mean Square — represents the effective continuous loudness of audio signals over time. Closely mirrors human ear integration times compared to raw instantaneous peaks.
PEAK
What is Peak Level?
The highest instantaneous pressure wave detected. Essential for capturing abrupt transient impulses like hammer strikes, claps, or explosive sound events.
MIC
Phone Microphone Limits
Consumer microphones are optimized for human speech, not laboratory acoustics. Hardware limits, AGC, and compression can affect readings above ~90 dB or below ~30 dB.
Protecting Your Hearing
Hearing damage from noise is permanent, but it is preventable — these are the exposure limits that matter most.
Safe Daily Exposure Limits
According to NIOSH guidelines, sustained exposure to sounds at or above 85 dBA can cause permanent hearing loss over time. The permissible exposure time drops by half for every 3 dB increase above 85 dBA.
8 h
at 85 dBA
4 h
at 88 dBA
2 h
at 91 dBA
15 min
at 100 dBA
Hearing protection (earplugs or earmuffs) is strongly advised above 85 dBA.
Deep Dive
Longer explanations for the questions that come up most when learning about sound measurement.
Why is the decibel scale logarithmic instead of linear?
The human ear has an extraordinary dynamic range — it can detect sounds from a whisper (0.00002 Pascals) to a jet engine (200 Pascals), a factor of 10,000,000 to 1. A linear scale would require unwieldy numbers with millions of units. A logarithmic scale compresses this immense range into a practical 0 to 140 scale that matches how human hearing perceives changes in loudness.
When should I choose A-weighting vs C-weighting vs Z-weighting?
A-Weighting (dBA): Best for general environmental noise, office spaces, classrooms, and OSHA/NIOSH compliance. It de-emphasizes low frequencies below 500 Hz where the ear is less sensitive.
C-Weighting (dBC): Ideal for music venues, subwoofers, engines, and heavy machinery where high-energy bass frequencies are significant.
Z-Weighting (dBZ): Zero-weighting flat response (20 Hz - 20 kHz), used for raw acoustic research and audio engineering testing.