Civil Engineering Reference
In-Depth Information
13
Noise and Vibration
Noise is the most impertinent of all forms of interruption. It
is not only an interruption, but is also a disruption of
thought.
Arthur Schopenhauer (1788-1860)
13.1
INTRODUCTION
This chapter deals with the effects of noise and vibration on human performance and
comfort. From an engineering design perspective, noise and vibration are close cousins;
vibration of a steel plate will cause noise. Many engineering measures that reduce
vibration will also cut noise. From a human performance and health perspective, they are,
however, quite different.
Noise is very physical and very noticeable to most employees. Questionnaire
investigations in industrial plants show that workers usually single out noise as the most
important ergonomics problem in factories (Karlsson, 1989). This is not totally
unexpected, because compared to many other ergonomic problems noise is very obvious
and concrete.
There are four different aspects that can make noise unacceptable in the working
environment:
1. Noise can cause hearing loss
2. Noise can affect performance and productivity
3. Noise can be annoying
4. Noise can interfere with spoken communication
In this chapter we first discuss several different methods for assessing the effects of
exposure to noise. We then examine some performance effects of noise that are likely to
affect an industrial worker, and we will discuss engineering methods for reducing noise
in the workplace. Table 13.1 gives some examples of typical noise levels.
13.2
MEASUREMENT OF SOUND
A sound-level meter is used to measure sound. It consists of a microphone, an amplifier,
and a meter that gives a visible reading in decibels (dB) on a scale. Most meters
incorporate three different types of weighting of a sound. These are known as the A, B,
and C scales (Figure 13.1). In particular, the dBA scale has achieved widespread use in
work environments. This scale (or weighting function) approximates
