INTERPRETING THE SOUND RATINGS OF A UNIT

Decibel (DB) Comparisons

Common Sounds

This is a tabular comparison of some common sounds based on decibel (dBA) values to show their ranks in terms of potential harm to hearing. The objective behind this comparison is to analyze the condition of the workers who are usually exposed to dangerous noise levels of some massive industries such as construction, lumber, mining, steel, and textile industries.

SOUND	NOISE LEVEL (dBA)	EFFECT
Jet Engines (Near)	140
Shotgun Firing	130
Jet Takeoff (100-200 Ft.)	130
Rock Concert (Varies)	110-140	Threshold of pain (125 dB)
Oxygen Torch	121
Disco/Boom Box	120	Threshold of sensation (120 dB)
Thunderclap (Near)	120
Stereo (Over 100 Watts)	110-125
Symphony Orchestra	110	Regular exposure of more than 1 minute risks permanent hearing loss (over 100 dB)
Power Saw (Chain Saw)	110
Jackhammer	110
Snowmobile	105
Jet Fly-over (1000 Ft.)	103
Electric Furnace Area	100	No more than 15 minutes of unprotected exposure recommended (90-100 dB)
Garbage Truck/Cement Mixer	100
Farm Tractor	98
Newspaper Press	97
Subway, Motorcycle (25 Ft)	88	Very annoying
Lawnmower, Food Blender	85-90	Level at which hearing damage begins after 8 hours (85dB)
Recreational Vehicles, TV	70-90
Diesel Truck (40 Mph, 50 Ft.)	84
Average City Traffic Noise	80	Annoying; interferes with conversation; constant exposure may cause damage
Garbage Disposal	80
Washing Machine	78
Dishwasher	75
Vacuum Cleaner	70	Intrusive; interferes with telephone conversation
Hair Dryer	70	Intrusive; interferes with telephone conversation
Normal Conversation	50-65
Quiet Office	50-60	Comfortable (under 60 dB)
Refrigerator Humming	40
Whisper	30	Very quiet
Broadcasting Studio	30
Rustling Leaves	20	Just audible
Normal Breathing	10
	0	Threshold of normal hearing (1000-4000 Hz)

The ear has different sensitivities to different frequencies. That’s why sound level meter circuits have weighing or attenuating filters to simulate the ear’s response. Though a noise level meter can instantly measure the present noise, it cannot measure the duration of the exposure. A “Dosimeter” or an integrated sound level meter must be used to measure the amount of noise a person is exposed to. The American Medical Association and the Canadian Hearing Society of Ontario are the greatest names among the sources of the above information. The Decibel table is developed by the National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892. January 1990.