Room acoustics

Study of this chapter will enable the reader to:

know the potential sources of sound and vibration within buildings;

know what is meant by noise;

understand how sound travels through a building;

understand what is meant by sound pressure wave, sound power level and sound pressure level;

know how to calculate sound pressure levels for normal building services design examples;

use sound levels at the range of frequencies commonly used in building services engineering;

understand how sound and vibration are transmitted through buildings;

be able to identify the need for sound attenuation vibration isolation;

understand and use the decibel unit of measurement of sound energy;

know the meaning and use of direct and reverberant sound fields;

calculate the sound pressure level in a plant room, a space adjacent to the plant room, in the target occupied room and in the external environment outside the plant room;

use logarithms to base 10 in acoustic calculations;

understand the principle of sound absorption;

calculate the sound absorption constant for a room at different frequencies;

know the sound absorption coefficients for some common building materials and constructions;

understand and use reverberation time and attenuation;

calculate sound pressure levels at different frequencies within a plant room;

know what a reverberant room and an anechoic chamber are;

use directivity index sound absorption coefficients, mean absorption coefficient and room absorption constant;

understand the behaviour of equipment at resonant conditions and how to minimize or avoid its occurrence;

calculate and use the sound pressure level in a plant room;

calculate the sound pressure level experienced at an external location from a plant room;

calculate the sound pressure level generated in a room or space that is adjacent to a plant room;

calculate the sound pressure levels at different frequencies that are produced in the target occupied room;

understand, calculate and use noise rating data;

know how the acoustic design engineer relates the noise output from plant systems to the human response;

be able to calculate noise rating curves;

know the noise rating criteria used for building services design;

plot noise rating curves, plant and system sound pressure levels and find a suitable design solution;

know the formulae used in practical acoustic design work;

be able to carry out sound pressure level and noise rating deign calculations, try different solutions to attenuate plant noise and be able to produce a practical design to meet a design brief.