At what point does sound become noise?

It’s a rare week when I don’t receive at least one email complaining about noise in a restaurant. Of course, complaints like that are totally subjective. A musician friend of mine plays in an enthusiastic – and very popular – rock band. He told me about an incident at a local bar that’s well known for its lineup of rock bands. During one of his breaks, he was approached by an indignant woman who told him that she and her friends had come to the venue to talk, and the music was disturbing that. Yes, you heard that right: she and her friends chose one of the most popular rock music venues in the area to get together and … talk.

The absurdity notwithstanding, there are noise complaints about eateries that actually do make sense. In fact, the noise level (not having to do with live music) in a restaurant has actually been proven to affect the diner’s perception of taste.

Over the last few years, many restaurants have been replacing fluffy carpets and fabric-draped walls with tile floors and walls made of wood, ceramic and even metal in the interest of looking more modern. Surfaces are often devoid of tablecloths in favor of exposed wood or stainless steel. Overstuffed chairs are now metal and vinyl. Ceilings with “acoustical” tiles (not really “acoustical” at all) are now “open plan.” That means all the metal works like air ducts, lighting, etc., are exposed. Yes, it’s a great look. But it’s a recipe for an acoustical nightmare.

Here at the beach, many of our eateries are located in old houses and Victorian beach cottages with low ceilings and relatively close quarters. Or they’re in large spaces with hard (but easy to clean) floors and lots of glass windows. A by-product of this trend toward austerity has been an increase in the apparent noise in the space. Sure, as with my rock club example above, some restaurants trade in loud music and raucous “people noise,” and have a loyal following of customers who come for the upbeat atmosphere. But diners who appreciate a quieter experience 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 materials covering the floors, ceilings and walls. In simple terms, the human ear is easily confused by sounds that reflect off hard surfaces. And that’s not all: The bigger the space, the more time it takes for sound to reach those surfaces – and to bounce back. At a certain point (acousticians call it the “critical distance”), the reflections begin to interfere with one another. That’s the point where the human brain perceives the resulting sound as a jumbled mishmash of unrecognizable noises. And that can be downright annoying. Bingo! Emails start arriving at my inbox.

Noise abatement isn’t cheap. As restaurants compete more and more in the price department, a several-thousand-dollar outlay for acoustical materials and design can be painful. But some restaurants are indeed addressing the issue as diners make their feelings known on social media and review websites.

One way to quiet things down is by installing specially mounted panels to “trap” the sound when it arrives at the ceilings or the walls, i.e., keep it from reflecting back. We call that “absorption,” and it’s a lot more involved than just gluing some packing foam to the ceiling.

Many acousticians use a combination of absorption and 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 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.

Another slightly more high-tech solution is what we call sound masking. Interestingly, adding sound to a space can actually make it seem quieter. Sound masking is the introduction of an ambient sound, similar to airflow through a vent, through speakers in the room. The sound is specifically engineered to reduce the intelligibility of conversational distractions to the human ear. When deployed properly, sound masking is barely noticeable.

Some Cape Region restaurants are turning to experts for systems designed to bring their interior layout and the resultant acoustical behavior into harmony. Depending on the clientele the restaurant wishes to attract, that expenditure could actually result in an increase at the bottom line.