Restaurant Acoustics

Hubbub. Everyone likes a restaurant filled with hubbub, which is not the same as a restaurant that is too noisy. Hubbub is “background noise”. Hubbub means to the owner that business is going strong and it means to the patron that people like to be here. 

Restaurant Acoustics

“It’s too Noisy...,” The single most common complaint about restaurants. It’s not about food, the waitress or dirty glasses, or any other employee caused problem, it’s about too much noise. Fix an employee problem and it’s back again in 2 years, but fix the noise problem and it's gone forever. Yet the owner/manager continues to say no to making changes in restaurant acoustics and continues to spend funds retraining employees. So what’s the problem with eateries and noise, the patrons and the owners?

If a restaurant is too noisy, that means that the place is full of people and business is booming, and owners like that. If it is too quiet, that means the place is almost empty and the owner doesn’t like that. Owners like the noise and don’t like the quiet. Owners don’t like anything that makes their restaurant quiet. No one goes into a quiet restaurant. No one likes to eat in a quiet restaurant. A quiet restaurant means something is wrong. And so the owners don’t like to add acoustics to quiet down a restaurant. We are using the “Q” word to talk about restaurant acoustics and the “Q” word is not the right word to use.

One of the better restaurant designs are large restaurants with high ceilings and tables spaced well apart, and of course, a menu and service to attract the customers, and keep them coming back. These spaces have a steady din of hubbub, that backfills any lull in the conversation. The tables are far enough apart that table top conversations are not overheard at adjacent tables. And there is a large glass lamp fixture over each table, which keeps table top conversations on the table top. But not every available commercial spaces meets these requirements. Many available commercial spaces are wide enough but have a lower ceiling. Low ceilings act like megaphones beaming sound everywhere, and loudly as long as it is in the horizontal direction. The commercial restaurant space is all too often just too noisy.

Privacy

The basic concept in developing a good sounding restaurant is a sense of privacy. It’s the feeling that one’s conversation is not being overheard by others nearby. How people know they have privacy is because they can’t exactly eavesdrop on the conversations around them. In order for people to have privacy they want to talk quietly and be heard clearly, just above the hubbub. By the time their voice travels out across other tables, it is lost in the hubbub. But speaking quietly and being heard is not exactly easy when the room is filled with hubbub. Here is where the low ceiling comes into play. The ceiling is shiny and reflects the vertical part of a table top conversation right back town to the table where it belongs, and then back up again, and then back down again. To have a quiet table top conversation we need a reflective ceiling.

In order to have privacy in a restaurant the intrusion of sound from afar must be blocked. Something has to be done to attenuate loud sounds from across the room. If we hear the neighboring table speaking up, we can also see the animated movements out of the corners of our eyes and expect to hear the sounds. But hearing equally loud sounds from somewhere across the room is annoying. We have no visual clue about that sound being made and so it becomes an intruding sound. Horizontal sound needs to be attenuated in a good sounding restaurant.

Table top conversations. It is a fundamental social event, eating and visiting at the same time. A good restaurant promotes table top conversation by insuring that people can visit with each other across the table, without a strained effort or raised voice. In addition to the direct sound between people at the table, the reflection of sound off the top of the table makes people's voices louder, without having to raise the voice. A good reflection off the ceiling of the restaurant also contributes to a bright and clear table top conversation.

The acoustic coffered ceiling system uniformly distributes large sections of highly reflective ceiling surfaces, separated by narrow strips of sound absorbing panels, otherwise known as acoustic beams. These ceiling vertical ceiling bounces are essential for clear table top conversations. This is one important reason that this system works best on lower instead of higher ceilings.

Technologies

Acoustic Coffered Ceiling

Acoustic Coffered Ceiling

And so, in good restaurant acoustics we want to reinforce table top conversations, allow for vertical reverberation and attenuate intruding sounds from across the room.   The ASC acoustic beam coffered ceiling system does just that in lower ceiling rooms.   

A little hubbub  is a good thing... and just the thought of adding sound panels to a restaurant brings chills to the owner, imagining how awful a quiet restaurant sounds. Hubbub provides a sense of welcome to the newcomers and privacy to the seated guests.  Hubbub encourages table top conversation and good fun.  When we work to revoice a restaurant, we sort out what is working from what is not working.

Most restaurants that have a noise problem are not on the drawing board but are up and running. Starting over, to redesign and remodel the restaurant to sound better is not an option.  There is a cost effective “magic bullet” that tends to work very well in most restaurant spaces that need the help.  It is the ASC Acoustic Beam Coffered Ceiling System.  It promotes the needed background ambience effect of hubbub.  It cuts down on the intrusive sounds from across the room and it supports crystal clear table top conversations.  And here is how it works.

The Acoustic Coffered Ceiling is a directional acoustic ceiling mounted grid.  It is officially a ceiling mounted acoustic baffle.  However it is disguised as a classic architectural element, the coffered or box beam ceiling.  It allows vertical sound to be reflected and horizontal sound to be absorbed.  It works exactly opposite of standard T-bar acoustical ceiling which absorbs vertical sound and reflects horizontal sounds.  

The system works best in wide and or long rooms with fairly low ceilings, 8 to 12 feet.  The height of higher ceiling rooms minimizes the ability of the acoustic coffered system to independently control vertical and horizontal sound and the ceiling system becomes an attractive general purpose noise control ceiling, making acoustic adjustments only in the reverb time.  The lower the ceiling and wider the space the more powerful and vivid becomes the performance of the acoustic coffered beam ceiling.

The Acoustic Coffered Ceiling typically will have 3 to 5 foot squares of existing ceiling separated by 6” wide and 2” deep sound absorbing faux beams.  Different depths or widths of acoustic beams produce more or less aggressive results in either the vertical or horizontal direction, as does changing the size of the grid pattern.  These faux beams are light weight, fire rated and install easily with nothing more than a few dabs of acoustic ceiling adhesive.   They are beveled and shaped to form any number of patterns, the most common of which is the mitered grid pattern.

The size of the exposed ceiling in the grid determines how bright the table top conversation will be.  The larger the ceiling grid, the lower is the vertical absorption coefficient.  A 4x4 grid with a 6” beam provides a vertical NRC of about 25%.  (Noise Reduction Coefficient).  Unlike an acoustic tile, that provides the same NRC, this system alternates small areas of 100% absorption with larger areas of 100% reflection.  This is very unlike typical acoustic T-bar ceilings, where the absorption and reflection is uniformly distributed.  With the acoustic coffered ceiling, the ceiling reflection is not dull as with T-bar ceilings, it sparkles.  

Sound traveling in a horizontal direction, grazing the ceiling runs into the sound absorbing sides of the acoustic coffered ceiling.  The depth of the acoustic coffered beams determines how aggressive it is with respect to absorbing the grazing horizontal or “cross talk” type of sound out of the restaurant air.

The reflective ceiling not only returns the table top conversation back down to the table top, which makes it more easily heard, but it supports the buildup of the background noise floor, the very important hubbub effect.  Because the ceiling is composed of large squares of reflective surfaces, and despite their being separated by sound absorbing edges, multiple vertical reflections are accommodated. 

When people are talking in a space that has an acoustic coffered beam ceiling they hear the table top conversation clearly, enjoy the sound masking or privacy effect of ongoing hubbub and are protected from loud and intruding sounds from across the room.    

Examples

The 3 existing conditions of Loudness, Privacy and Clarity (LPC) were estimated to be 4, 3, 1; very loud, reasonably private and poor clarity.  The owner wanted moderate background noise, reasonable privacy and good clarity for table top conversations; LPC rating 2,3,3.  This means we need to drop the background noise, retain the existing privacy and improve table top clairity. 

The room was a deep and wide restaurant with a fairly low, 10’ ceiling.  The surfaces were painted sheetrock, huge plate glass windows and linoleum floor.  Wall mounted acoustics would be too far away to control the sound in the middle of the room, it would only quiet things around the perimeter, which might be OK for a nightclub but not for this Bistro.  That leave ceiling mounted acoustics.  We want to turn the volume of reverberation down which means we need to add acoustic panels to the ceiling.  We want to retain conversation clarity, which means we do not want sound panels on top each table. We also want to retain privacy, which means we want to absorb or block sound from crossing the room.  We want to improve tabletop clarity, which means we want to introduce more reflecting surfaces near the table. 

Converting the floor plan from open tables to booths with an acoustic coffered ceiling is an excellent way to achieve the desired effect.  The coffered ceiling adds acoustics to the room, aggressively absorbs sound traveling across the room and only lightly absorbs sound that is reflecting vertically.  This quiets the buildup of noise, quiets sounds from across the room and retains hubbub, vertical reverberant hubbub. If the tables are far apart, inter table privacy will be achieved, but if the tables need to be closer, some sort of sound barrier effect is needed between tables, and the barrier should reflect sound from a table back to the table so the conversational sound levels are improved.  The owner chose booths in the middle of the room and spaced tables around the perimeter and was very pleased with the change because his target clientele returned and the restaurant is busy, busy, busy...