Reflecting on the nature of sound and noise in restaurants

Even after 10 years of scribbling on this page, I’m never really sure which columns will result in a flurry of emails, texts and/or general commentary.

I wrote a few weeks ago about the number of new restaurants opening in spite of the increasingly prolonged restrictions on seating and, consequently, any hope of profit. Seemed innocent enough, but that article sparked a surprising number of responses about noise levels in restaurants - including some recently opened and others with a long history here at the beach.

I wrote a couple of years ago that sound and noise levels (they are two different things) tend to match the concept of the restaurant. A sports bar with 150 TVs will be pretty noisy. A quiet steakhouse will be just the opposite. But there are a whole lot of places in between.

For example, as part of a general move toward austere design, carpets are being replaced by tile and slate floors. Walls that were draped with fabrics are now wood, drywall or even metal. Surfaces are devoid of tablecloths in favor of exposed wood or stainless steel. Overstuffed chairs are now metal and vinyl. Drop ceilings with “acoustical” tiles (not really “acoustical” at all) have given way to “open plan,” i.e., devoid of any ceiling other than the roof itself. That means that air ducts, lighting, wires, pipes, etc., are open and exposed. If done right it can be a great look, but it can also make for an acoustical nightmare.

When I refer to restaurant noise, I’m not talking about live music. Most people are smart enough not to select a rock ‘n’ roll bar for an intimate conversation. I’m talking about what is scientifically referred to as “ambient” noise. Many of our eateries here at the beach are located in old beach cottages with low ceilings. Or they’re in large spaces with hard (but easy to clean) floors, and lots and lots of glass windows. Sure, some restaurants trade in live music and raucous “people noise,” and enjoy a loyal following that appreciates the upbeat atmosphere. But diners in search of a quieter spot are finding that those experiences are becoming fewer and farther between.

Unpleasant noise isn’t entirely about the number of people in a restaurant. It’s more about the shape of the room and the hardness of the floor, ceiling and walls. There’s a lot of physics and physiology involved, but suffice it to say that the human ear is easily confused by sounds that reflect off hard, unyielding surfaces. And as the walls, floors and ceilings get farther apart or even more reflective, the time it takes for the sound to reach those surfaces - and to bounce back - is increased.

At a certain point (acousticians call it the “critical distance”) those reflections interfere with one another, and the human brain can no longer recognize where they came from. They are perceived as a jumbled cacophony that can be downright annoying. Shortly thereafter, emails start arriving at my inbox.

Noise control and abatement is not cheap. As restaurants compete more and more in the price department, a several-thousand-dollar outlay for acoustical design and materials can be painful. One way to quiet things down is by installing specially mounted panels to “trap” sound into not reflecting back into the room. We call that “absorption.” And it’s a lot more involved than just gluing egg cartons or packing foam to the ceiling.

Many acoustic designers include a concept called “diffusion.” Imagine looking at something through frosted glass: The light is scattered in such a way that it’s hard to see what’s on the other side. Diffusion does the same thing, but with sound: Rather than allowing it to reflect directly back into the room (like a mirror with light), it scatters the sound waves in all directions. This is much less annoying to the human ear.

A more high-tech solution deployed in large spaces such as airports, malls, casinos, etc. is called sound masking. Believe it or not, actually adding sound can make the space seem quieter. This process involves the introduction of a specific type of noise (sounds sort of like airflow through a vent) through speakers. Because of the physiology of our hearing, that sound reduces the intelligibility of nearby conversational distractions. When used properly, sound masking is barely noticeable.

More and more Cape Region restaurants are turning to experts to design cost-effective systems to bring their interior layout and its acoustical behavior into harmony. Despite everything that is working against their success these days, the quality eateries here at the beach are still working hard to keep the business of eating afloat.