Sound Pressure Level Reference
Reference SPL levels (dB) for everyday sounds.
Overview
The sound pressure level reference is a table of typical dB SPL values for everyday and professional sound sources, from the threshold of hearing (0 dB) to threshold of pain (around 130 dB). Look up a whisper, a vacuum cleaner, a chainsaw, a rock concert, or a jet engine and see roughly how loud each is in calibrated units.
It's used by acoustic consultants explaining noise impact, hearing-conservation officers training workers on exposure, podcasters and broadcasters calibrating monitor levels, and curious listeners trying to put their own listening habits in context. Knowing that a busy restaurant is roughly 70 dB and a leaf blower is 100 dB helps you reason about hearing risk, mix loudness, and room acoustics intuitively.
How it works
Sound pressure level (SPL) measures sound pressure relative to a reference of 20 micropascals — the quietest pressure a healthy young ear can detect at 1 kHz. Because pressure varies enormously in the real world, SPL uses a logarithmic decibel scale: 20 x log10(p / p_ref). That compresses a billion-fold range of pressures into a 0-130 number that maps closely to perceived loudness.
The dB(A) weighting filters the spectrum to match human hearing sensitivity — boosting the 1-4 kHz region and rolling off below 500 Hz and above 8 kHz. Most regulatory and product noise levels quoted in everyday literature use dB(A). Subjective loudness roughly doubles for every 10 dB increase: a 90 dB blender feels twice as loud as a 80 dB conversation, and four times as loud as a 70 dB office.
Examples
0 dB SPL Threshold of hearing (1 kHz)
30 dB SPL Quiet bedroom at night
60 dB SPL Normal conversation at 1 m
85 dB SPL Heavy traffic, OSHA workday limit
100 dB SPL Hand-held power tools, chainsaw at operator
120 dB SPL Loud rock concert front-of-house, threshold of discomfort
140 dB SPL Jet engine at 30 m, immediate hearing damage
FAQ
At what level should I worry about hearing damage?
Sustained exposure above 85 dB(A) accumulates damage. Every 3 dB above that halves the safe duration. 100 dB is safe for only about 15 minutes per day under typical exposure standards.
Why doesn't doubling the dB number double the perceived loudness?
Decibels are logarithmic. Perceived loudness roughly doubles every 10 dB, so 80 dB feels about twice as loud as 70 dB, not 14 percent louder as the numerical change implies.
What's the difference between dB SPL, dB(A), and dBFS?
dB SPL measures acoustic pressure in the air. dB(A) is dB SPL filtered by a curve matching ear sensitivity. dBFS is digital-domain decibels referenced to full scale; 0 dBFS is the loudest representable digital signal.
How do these levels relate to mixing in a studio?
Reference monitoring is typically 79-85 dB SPL at the listening position for film and music. Higher levels mask quiet detail; lower levels misrepresent low-frequency content.
Can two 70 dB sources combine to 80 dB?
No — two equal incoherent sources add 3 dB. You'd need ten equal sources to add 10 dB.