Civil Engineering Reference
In-Depth Information
FIGURE 13.7
Voice level and the
distance between the speaker and the
listener as a function of PSIL noise
level.
distance from a speaker to a listener is given as a function of the PSIL value. The
necessary speech level is then characterized as normal, raised voice, very loud voice,
shout, maximum vocal effort, or limit for amplified speech. Thus, for example, if the
PSIL value is 65 dB and the distance to a listener is 8 ft, the speaker would have to talk
with a very loud voice. PSIL has also been used to characterize office communication in
private offices and secretarial offices (Beranek and Newman, 1950). Of particular interest
is the effect of noise on telephone use. For a PSIL value greater than 60 dB it is difficult
to use a telephone, and for a value greater than 76 dB it is impossible to talk on the
telephone.
Exercise: How to Use PSIL
To evaluate the ease of communication in an industrial plant, the noise was measured for
three octave-bands: 500, 1000, and 2000 Hz. The recorded noise levels were 75, 80, and
82 dBA, respectively.
1. Calculate the PSIL value.
2. Using the values in Figure 13.7, what is the maximum distance at which two
individuals can communicate without raising their voices?
3. Given the social unacceptability of a very close distance, what would be the necessary
speech level if the distance was 1.0 m?
13.11
WHOLE-BODY VIBRATION
In today's work environment machines can often cause vibration, which in some
circumstances may pose a health hazard (Griffin, 1997). There are two major kinds of
vibration: whole-body vibration and hand vibration. The latter is commonly referred to as
segmental vibration, implying vibration of the extremities. In addition to these, there is a
third phenomenon, sea sickness, which involves exposure to slow vibrations in the range
