The concept of calm
At Sandwell General Hospital in Birmingham, England, replacing the old, imperforate metal ceiling with a highly sound-absorbent Class A ceiling has greatly reduced noise levels in the corridors of Priory Ward 4.
When Sandwell General Hospital embarked on the project to refurbish Priory Ward 4, Cundall carried out measurements of noise levels before and after. Prior to the refurbishment, the ceiling consisted of imperforate metal tiles, common in older hospitals.
It was quite a noisy environment, since all the surfaces were smooth with hard finishes. The only absorption came from curtains separating the corridor from the wards.
Owing to the constraints of testing in a working hospital environment, ceiling changes were allowed only in the corridor area. Yet this action alone produced a significant improvement in the acoustics in both the corridor and the ward.
“The quite simple and obvious conclusion is that the corridor area got quieter. An important reason is that the sound doesn’t travel as easily as it did before,” explains Andrew Parkin. “Our report shows that a simple refurbishment can have a quite profound impact. The activity noise level was reduced by up to eight decibels, which is perceived as almost half as loud.”
The whole place gets quieter, people behave better, and it simply becomes a better environment to be in.
Within the refurbished corridor area, the old nurses’ office has been replaced by an open-plan nurses’ station. While improving sightlines and access to patients, this would be expected to be noisier than the previous layout, but noise levels are still lower.
”In the nurses’ station there are people talking, phones ringing, alarms sounding, bins being opened and closed, and so on. Most of these sounds are of short duration and are now reduced at source. The sound gets absorbed more quickly and travels shorter distances.”
According to Andrew Parkin, the acoustics of corridors in the healthcare sector is an underestimated and overlooked problem. One factor of great importance is infection control. “Some hospital managers think you can’t have sound absorption because it hampers infection control. But you actually can combine sound absorption and infection control. It’s a matter of educating the right people that sound absorption and infection control can coexist.”
Andrew Parkin talks about “the concept of calm”, identifying this as the key finding in the report. Simply introducing absorbers changes the overall ambience of the space. “This is difficult to quantify objectively, but is best portrayed by the background noise,” he explains. “When spaces are reverberant, there is a tendency for noise to build up, and for people to speak louder to be heard above the noise. With well-controlled reverberation, people tend to be quieter, either consciously or subconsciously. Although the background noise level will be reduced by only three to four decibels, the human factors make the overall noise reduction much more significant.”
Andrew Parkin points to the Essex Study on education environments as an example. “That study shows better acoustics have such a positive impact that goes beyond the physical aspects. The whole place gets quieter, people behave better, and it simply becomes a better environment to be in.”
This animation explains why the environment at Sandwell General Hospital is now perceived as half as loud as before:
Text: Lars Wirtén