Page 57 - The Master Handbook Of Acoustics

32 CHAPTER TWO

Table 2-5. Some common sound-pressure levels and sound pressures.

Sound
Sound level*
pressure (decibels,
Sound Source (Pa) A-weighted)
Saturn rocket 100,000. 194
(one atmosphere)
Ram jet 2,000. 160
Propeller aircraft 200. 140
Threshold of pain 135
Riveter 20. 120
Heavy truck 2. 100
Noisy office, } 0.2 80
Heavy traffic
Conversational speech 0.02 60
Private office 50
Quiet residence 0.0002 40
Recording studio 30
Leaves rustling 0.0002 20
Hearing threshold, good ears at
frequency of maximum sensitivity 10
Hearing threshold, excellent
ears at frequency maximum
response 0.00002 0
* Reference pressure (take your pick, these are identical):
20 micropascal (µPa)
0.00002 pascal
–5
2×10 newton/meter 2
2
0.0002 dyne/cm or microbar

from 100,000 Pa (100 kPa), which is atmospheric pressure to, 0.00002
Pa (20 µPa), but this range is reduced to quite a convenient form in the
level column. The same information is present in graphical form in
Fig. 2-2.
Another way to generate a 194-dB sound-pressure level, besides
launching a Saturn rocket, is to detonate 50 pounds of TNT 10 feet
away. Common sound waves are but tiny ripples on the steady-state
atmospheric pressure. A 194-dB sound-pressure level approaches the
atmospheric and, hence, is a ripple of the same order of magnitude as