Sound Pressure Levels - How much is too much?

Experts agree that continued exposure to sounds pressure levels (SPL) above 85 dBA over time, will cause hearing loss. To know if a sound is loud enough to damage your hearing, it is important to know both the SPL (measured in decibels, dBA) and the length of exposure to the sound. In general, the louder the noise, the less time required before hearing loss will occur.

According to the National Institute for Occupational Safety and Health (1998), the maximum exposure time before hearing damage at 85 dBA is 8 hours. At 110 dBA, the maximum exposure time is one minute and 29 seconds. If you must be exposed to noise, it is recommended that you limit the exposure time and/or wear hearing protection.

The following are decibel levels of common noise sources around us. These are typical levels, however, actual noise levels may vary depending on the particular item. Remember noise levels above 85 dBA will harm hearing over time. Noise levels above 140dBA can cause damage to hearing after just one exposure.

Points of Reference measured in dBA or decibels:

• 0 - The softest sound a person can hear with normal hearing
• 10 - normal breathing
• 20 - whispering at 5 feet
• 30 - soft whisper
• 50 - rainfall
• 60 - normal conversation
• 110 - shouting in ear
• 120 - thunder

Home 50 - refrigerator 50 to 60 - electric toothbrush 50 to 75 - washing machine 50 to 75 - air conditioner 50 to 80 - electric shaver 55 - coffeemaker 55 to 70 - dishwasher 60 - sewing machine 60 to 85 - vacuum cleaner 60 to 95 - hair dryer 65 to 80 - alarm clock 70 - TV audio 70 to 80 - coffee grinder 70 to 95 - garbage disposal 75 to 85 - toilet flush 80 - toaster 80 - doorbell 80 - ringing telephone 80 - whistling kettle 80 to 90 - food processor 80 to 90 - blender 80 to 95 - garbage disposal 110 - baby crying

Work 40 - quiet office or library 50 - large office 65 to 95 - power lawn mower 80 - manual machine, tools 85 - handsaw 90 - tractor 90 to 115 - subway 95 - electric drill 100 - factory machinery 100 - woodworking class 105 - snow blower 110 - power saw 110 - leafblower 120 - chain saw, hammer on nail 120 - pneumatic drills, heavy machine 120 - jet plane (at gate) 120 - ambulance siren 125 - chain saw 130 - jackhammer, power drill 130 - civil defense siren 130 - percussion section at symphony 140 to 150 - airplane taking off 150 - artillery fire at 500 feet 180 - rocket launching from pad

Recreation 40 - quiet residential area 70 - freeway traffic 85 - heavy traffic, noisy restaurant 90 - truck, shouted conversation 95 to 110 - motorcycle 100 - snowmobile 100 - school dance 110 - bar or club music 110 - busy video arcade 110 - symphony concert 110 - car horn 110 to 130 - rock concert 112 - personal audio player, with headphones, on high 117 - football game 120 - band concert 125 - auto stereo (factory installed) 130 - stock car races 150 - firecracker 156 - capgun 157 - balloon pop 162 - fireworks (at 3 feet) 163 - rifle 166 - handgun 170 - shotgun

Remember that the decibel (dB) is a logarithmic unit, meaning that you cannot add and subtract dB like ordinary numbers. For example, an increase of 3 dB is a doubling of the "strength" of the sound, and an increase of 10 dB means that the sound is 10 times as loud; i.e., 70 dB is 10 times as loud as 60 dB.

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