Civil Engineering Reference
In-Depth Information
3. Can noise degrade repetitive assembly?
4. Can noise improve performance in problem solving?
13.9
ANNOYANCE OF NOISE AND INTERFERENCE WITH
COMMUNICATION
There are also psychological effects of noise; people reportedly become irritated and
annoyed. But the amount of irritation depends on the circumstances. Much research has
gone into assessing the effect of noise (e.g., traffic noise) on communities. Sperry (1978)
noted that there are many acoustic as well as nonacoustic factors which influence the
reaction to traffic noise. Among the nonacoustic factors are the time of day, the source of
noise, and the attitude of the exposed person. The nighttime tolerance level for noise is
about 10 dB lower than the daytime tolerance. Noise from aircraft is perceived as more
annoying than the noise from automobiles and trucks. In fact, vehicular noise needs to be
about 10 dB higher than aircraft noise to be equally annoying. Finally, the attitude to
noise is very important. Comparative studies have demonstrated that individuals living in
Rome, Italy, tolerated a 10 dB greater noise level than did people in Stockholm, Sweden.
Is this a case of stiff Swedes and
laissez faire
Italians?
Surveys in industry have shown that noise is the primary source of dissatisfaction or
annoyance (Karlsson, 1989). Perhaps this is because noise is so physical and clearly
evident that people complain about it. Certainly it is easier to complain about noise than
to formulate complaints about abstractions, such as the presentation of information on
displays, even though the latter may be far more important to the task. The author once
visited an air traffic control tower to make a survey of ergonomic problems. The air
traffic operators' first complaints were of uncomfortable chairs. Later we found severe
problems with the information that was presented. For example, the design of displays
that illustrated how airplanes were taxiing and lining up on the ground for take-off was
relatively complex. The modification of the information displays was clearly the most
important ergonomic problem. But the issue is somewhat abstract, difficult to think of,
and difficult to talk about.
13.10
INTERFERENCE OF NOISE WITH SPOKEN
COMMUNICATION
Noise is a well-qualified problem because it disrupts communication, and some
ergonomics standards have postulated that the noise level should be no greater than 55
dBA in office environments, in order to facilitate communication (Human Factors and
Ergonomics Society, 2003). There are two common methods for evaluating the effect of
noise on communication: preferred noise criteria (PNC) curves, and preferred speech
interference level (PSIL).
