Glossary
dBA noise rating
dBA noise rating is an A-weighted decibel measurement used to express compressor sound pressure level at a standard distance (typically 1 m per ISO 2151) — the unit that captures how loud the unit actually feels to human hearing.
What it is
Sound pressure is measured in decibels, but raw dB values give equal weight to bass rumble and treble whine, neither of which the human ear hears as strongly as midrange. The A-weighting curve attenuates the bass below roughly 500 Hz and the extreme treble above 6 kHz, leaving a number that tracks perceived loudness. Compressor noise tests in catalog data sheets are published under ISO 2151, which standardizes microphone position, room treatment, and load condition, while ISO 3744 covers the related sound-power method used for enclosure design.
Why it matters
OSHA 1910.95 sets the workplace ceiling at 90 dBA as an 8-hour time-weighted average, with hearing-conservation triggers at 85 dBA. Practical shops aim well below that: typical industrial rotary screws ship at 65-78 dBA, reciprocating piston units run 80-95 dBA, and dental or medical scroll compressors come in below 55 dBA. A 10 dB increase is perceived as roughly twice as loud, so a 75 dBA unit installed next to a 65 dBA unit doubles the apparent noise floor of the room.
How it is used in our catalog
Most cf_compressors rows carry a noise_dba field where the manufacturer publishes it. The quietest catalog examples include the Powerex SES oil-less scroll and the Anest Iwata SLE series; the loudest are industrial duplex packages such as the Quincy QT-54. Sort by noise to compare equivalent CFM bands across drive types.
Common questions
How much louder is +10 dB?
About twice as loud to the human ear. The decibel scale is logarithmic, so +10 dB is 10x the sound power but only ~2x the perceived loudness. +3 dB doubles power but is only just noticeable.
How much does an enclosure reduce dBA?
A sound-attenuated cabinet typically cuts 5-10 dBA off the bare-airend rating, which is why catalog “enclosed” variants often list a quieter number than the same airend in a “base-mount” or “tank-mount” trim. Cabinet seals and inlet baffling matter as much as the panel itself.
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