Kaito Sushi Bar
A Case Study
Have you ever been to a restaurant that the noise level was so high you could not hear the person sitting across the table from you? Forget hearing the waiter or the bus person asking if you would like lemon with your water. You even started thinking that it might be better to get your food to go and eat it outside since the noise levels outside were lower than those in the restaurant. I know many have thought this exact same thing about their favorite eating and watering places. I know I did with my favorite sushi bar Kaito in Seal Beach, California.
What are the acoustical issues facing restaurants? They focus on reflections off of the walls, ceiling, and floors. Walls are usually drywall to save money. Ceilings are drywall or some type of suspended system that covers up HVAC and other unsightly objects. Floors are usually concrete or tile for easy maintenance since fluid and food are spilled on them. Glass windows to show the storefront to the street usually cover the complete front wall surface. Signage and shelves to support bottles and more glassware on the side walls. Glass on the walls and glass on the front wall. There go our reverberation times.
In restaurants, we have background music. It has two functions. It is for the customers to listen to and hopefully enjoy. The second task associated with the background music is to conceal lip smacking and noises associated with chewing and eventually eating. Along with the music, we have speech intelligibility. Clients must hear each other speak, they must hear the staff explain the daily specials, and the staff must hear them when they order. All of this interaction coupled with multiple sources of noise.
Every human mouth can be acoustically modeled the same as a 3″ speaker. A human will output energy from 90 – 2,000 Hz. just like a 3″ driver. Using this paradigm, we have multiple noise sources all through the restaurant. Some areas of the sushi bar can have tables with 4 or more 3″ human speakers. The sushi bar area can have 8- 12 3″ monitors concentrated in a small physical area. The amplitude and frequency range increase exponentially with the consumption of alcohol. This increase in amplitude must be addressed.
With multiple sources spread throughout the 600 square foot sushi bar, we must treat the four walls and ceiling. We need that surface area to have enough square footage of coverage for sound absorption technology. With middle and high-frequency sound absorption management, we need surface area availability in order to have enough space for treatment. We use the acronym TAP: type, amount, and position. We must use the correct type of absorption to achieve speech intelligibility, we must use the correct amount, and the correct room position.
What is our goal for reverberation times to achieve speech intelligibility? The Sushi bar measured over 3 seconds which is not what we want. In this case, I had permission to take the Rt-60 times down to professional recording studio levels. I had the ability to take it down to 1 second which for 30 people in 600 square foot is great for speech intelligibility rates and levels is never done. We wanted to see how quiet we could get it without calling attention to the acoustical treatment.
Surface Area Needs
We took a 600 square foot room and added 300 square feet of sound absorption technology. Panels were of two thicknesses. We had 2″ deep panels on walls. We had 4″ deep panels over higher energy areas in the ceiling. Adding it all up, we had 20 – 30 sources, 600 square foot room, 300 square feet of sound absorption technology distributed throughout the room, a starting Rt-60 of over three seconds and ending up with a 1 second overall reverberation time after treatment. Welcome to a sushi bar that sounds as good as a recording studio.
“I have been coming here for years. Its always been too loud. A welcome change!” – Bill H.
“I can order without raising my voice. I can hear the waiter without asking a second time.” – Julia M.
“No more shouting my order above the crowd. I can just ask for this or that. Very nice.” – Sam B.
“I just ask for my food in a normal voice at the sushi bar. The chefs don’t cup their hands over their ears anymore.” – Jan K.