Call centre room acoustics

Call centres are acoustically challenging environments. Australian/New Zealand Standard AS/NZS 2107:2000 “Recommended design sound levels and reverberation times for building interiors” addresses call centres.

Recommended sound pressure level value in use (LAeq)
Satisfactory = 40 dB(A), Maximum = 45 dB(A)

Comments: my experience of call centres is that they belong to the category of spaces where reverberation time is an indicator of an amount of absorption rather than a descriptor of the reverberant characteristics. The issue is to efficiently absorb the large amounts of energy created in the room, so as to avoid the cocktail/build up effect as described by call centre operators and managers: “… users are turnig the volume up too high…” and probably speaking louder than necessary (they cannot hear themselves speaking) which in its turn leads to a higher sound pressure level in the room, which etc… Laeq = 45 dB(A) is therefore a reasonable level to target.
Recommended reverberation time value (T)
0.1 to 0.4 s
Comments: A reverberation time of 0,1 s might be difficult to achieve in a large volume, while 0,4 s is achievable. I would estimate that you need to cover an equivalent of between 100 and 130% of the floor surface (i.e. on walls and ceiling) with absorbers complying to Absorption Class A (according to ISO 11654)
The standard writes also: “Where the control of reverberation in spaces is carried out for noise control purposes, the reverberation time should be minimized as far as practicable unless the designers of the space intend to provide a particular acoustic ambience”
NOTE: The location of sound-absorbing surfaces and sound-reflecting surfaces required to achieve the design reverberation time is important.
Short case study: “Conversion of an industrial building into a modern call centre at Lakeland Ltd” (or dial +44 15394 88100 and experience the acoustics over the phone!)