INSULATION
Why the UK’s cafe culture needs less reverb
Paul Absolon of CMS Danskin Acoustics looks at solutions to reverberation problems in noisy cafes, which are increasingly prevalent in the UK
he proliferation of coffee shops over the last few decades can’t have escaped anyone’s attention. Even before the arrival of Starbucks in 1998, the growth of the nation’s cafe culture was in full swing. Between 1993 and 1997, the number of coffee outlets in the UK increased by an incredible 847 per cent. As a nation, we consume a startling 95 million cups of coffee every day, and the coffee industry contributes over £17bn to our economy, creating hundreds of thousands of jobs.
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Given the ubiquity of cafes – not just on the high street but in workplaces, universities, retail spaces, public buildings – why do so many of them test people’s patience with dreadful acoustics? There are two contributing factors. The first is reverberation. The second is the Lombard Effect.
Reverberation
When a sound wave strikes a hard surface, it is reflected. This is known as reverberation. The length of time it takes the ‘sound pressure’ of this wave to fall by 60 decibels after the original sound has ceased is known as the reverberation time. In some environments, such as auditoria, a certain amount of reverberation is desirable in order to prevent sound ‘drop-off.’ In most environments, however, it’s problematic.
Reverberation is prevalent in environments with lots of hard surfaces. Now, think of your typical cafe environment: all those wipe-clean tables and countertops; those wooden floors; all that steel and chrome coffee-making machinery; all that crockery. Reverberation is guaranteed.
The Lombard Effect
According to the UC Berkeley Phonology Lab Annual Report (2008), “the Lombard Effect is a phenomenon in which
ADF NOVEMBER 2019
speakers alter their vocal production in noisy environments, such as loud parties or restaurants.” In other words, in an attempt to be heard over gurgling espresso machines, clattering cutlery, clinking crockery, piped-in music and other people talking, we increase the volume and pitch of our voices. This adds to the problem, leading others using the space to raise their voices, which means we have to raise our voices, which leads to an exponential rise in volume. The high levels of reverberation typical to coffee shops massively exacerbate this problem.
Solutions
The reverberation issue is the simplest to resolve; and by solving this problem, you may effectively combat the Lombard Effect by virtue of reducing the overall noise in the establishment.
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The reverberation issue is the simplest to resolve; and by solving this problem, you may effectively combat the Lombard Effect by virtue of reducing the overall noise in the establishment
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