DECIBELS

As of March 2003:
A stock 2006 V Rod makes 95-96 db outside of our dyno room, in the shop, 15ft away.

 

dB
EXAMPLE                                                        
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
145
170
200
threshold of hearing
rustling leaves
very soft whisper at 1 ft.
soft whisper at 5 ft.
normal house
light traffic at 100 ft.
normal speech at 3 ft.
hair drier
noisy restaurant
train whistle at 500 ft.
elevated train overhead
discomfort, boiler factory
nightclub dance music at 10 ft.
threshold of pain
firecracker
one time may cause permanent hearing loss
jet engine
sonic boom when plane is 1000 ft. overhead
(a Vietnam jet pilot trick. When that happened at 200ft, you would be instantly knocked to the ground.)
 

The decibel scale is based on a logarithmic equation (similar to the Richter scale for measuring earthquakes).

If a sound source increases by 6dB, it has twice the SPL (sound pressure level). For us to actually perceive a sound to be twice as loud, it needs to be increased by 10dB.

That means that a 12dB increase is four times higher SPL, but we perceive it only a little more than twice as loud.

 

OSHA (Occupational Safety and Health Administration) has laws regarding sound level exposure times for people working in loud or noisy environments for extended periods of time.

 
SPL in DbA Maximum daily exposure in hours
90
95
100
105
110
115
8
4
2
1
.5
.25 or less
 

OSHA 2206 (1978)