Call Centre Acoustics

Call Centre Acoustics.

Acoustics in Call Centres and Open Plan Offices are both important however the background noise produced by staff in open plan offices is generally lower as quiet work (such as paperwork) is being performed and in this environment there is a greater need for speech privacy.

In a call centre the majority of staff are using headsets and when talking to clients simultaneously it is estimated that 15 people produce an A-weighted speech-noise level of around 55dB as opposed to 44dB in a standard open plan office.

Call centres fall into the grade 3 category for privacy with a permitted signal-to noise-ratio of around 9dB.

ASTM International Standard E2638-10 defines five levels of speech privacy/security for enclosed meeting rooms and offices (see table).

What factors contribute to poor Acoustics in Call Centres?

Background Noise Levels

• Noise Generated from poorly designed HVAC systems or other external noise sources.
• Noise spilling into an area from a noisy canteen or passage.
• Number of people operating in the airspace.
• The more noise sources the louder the background noise and as the background noise increases the agents raise their voices which further increases noise levels.

Room Reverberation time (RT60)

• Sound is bouncing off hard surfaces (walls, ceiling, floor) and arriving back at the microphone at difference times.
• Volume and shape of airspace.
• Presence of early reflections.
• Sound focusing or late arrival, high level reflections.
• The direct to reverberant ratio.
• Direction of sound arriving at the listener.
• Direction of interfering noise.

Other Factors Affecting Speech Intelligibility in Call Centres.

• Loudness and signal to noise ratio.
• Microphone choice and pick up pattern.
• The number of people operating in the airspace.
• Talker annunciation/rate of delivery.
• Listener acuity.
• Gender of talker.
• Vocabulary and context of speech information.

How to improve Speech Intelligibility in Call Centres?

• Measure what the existing background noise levels are.
• Measure the reverberation time in the existing space and then scientifically calculate how many sabines of absorption is required to reach the recommended reverberation time.

All Acoustic Products have varying amounts of absorption and at different frequencies.  The absorption properties also vary depending on the way the Acoustic Product has been measured and their intended application.

There are three ways of reducing Reverberation.

• At the source.
• In the Transmission Path.
• At the Receiver.

If the Acoustics are addressed and there is still problems with the audio quality one would need to determine whether it is the network, software provider or other issues contributing to the quality problems.

Acoustic Worx has developed a range of Highly Effective Acoustic Products for Call Centre Applications which have been specifically tuned to the frequency range of speech.

What is a Mean Opinion Score?