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Analysis of over 20 dining spaces that suffered from suflicient -
acoustic issues to drive the owners to call in an acoustician " _ ’ K‘
had a variety of materials in the rooms, with some establish- ,

ments having almost no sound-absorbing surfaces (meaning 7v. "—"_'
hard floors, walls and ceilings), whereas others had some 5. I -"Mm-H“
absorbing materials, as shown in Figure 2. I : :3 i H E

. . . . ‘ t ’ in

Acoustic Design In Restaurants ' , ‘ , 1‘ , I l -
The rooms that had absorbing materials but still needed i.nter- , fig‘. ll if‘ E i l‘ - .9‘, 7
ventions often had the absorbing material on the floor in the _ 1 3 1:‘ -‘B_ i I “f:
form of carpet. Some rooms had heavy carpet and drapes 5.. L ‘ 3‘ 4-
along the windows, yet still resulted in unsatisfactory acous- »_,, ; 7 ‘I . as ‘ ; .
tic environments. Where the absorbing material is installed ‘ lg ’ _ ”"x - -‘ .
matters! Certainly, adding absorbing material anywhere will 7 ‘ T ' 4 0
cut down on the amount of reflected energy in the room (to

some extent), but putting it in areas where sounds are more

likely to actually interact with the material will result in a ,'

more favorable acoustic environment. As more absorbing

material is added to the space, the :1 gets higher. C, _ '

- . .4 .

It is also very important to think beyond the simple equa- cl ~ ‘

tions that we use to calculate “bull? performance variables ‘T. .1‘ V ‘ \
such as the average absorption coefficient and consider the 8. I 7
above discussion. Once while teaching a design workshop ,, v _V - _ _ ,, L ,

in Mexico City, an architect asked if it was possible to solve I ‘ 534% V =————‘—‘
the noise issue in one of the most famous restaurants in the ' °'_-T ‘ _. _

city in a simple way. The architect wanted to know if put- l ‘ V

ting acoustical treatment under all the tables and chairs ‘ L

would solve a “big” noise problem. The entire workshop — A e \

group talked through this proposed solution and came to . § \

the conclusion that the likely outcome would be a 1 an level ‘ \ ,

reduction because no more than one-half of the floor area —’ \ ‘

could be covered, and even if this was done, the likelihood of * \ — ’

getting sound up under the tables and chairs was not so good. gr I _ _ _ '

"l "’ 3'. _'|__i‘3.._ — 2 chad

The untreated rooms that required acoustic treatment had __4 ' ' '— — in
an E1 of 0.12, with a range of 0.05 to 0.23, as seen in Figure 3, * ’ T —“ ‘ 3' ‘_

red, as the “untreated” option. Adding absorbing materials _ ‘\“'_":7 -

to 50% of the walls or ceiling resulted in an a of 0.20 (which

is typically considered the “break point” between an acous- /”' ‘
tically live room and a room that begins to absorb sound). ‘
This step might be considered a “first pass” in attempting to -

control excessive reverberation. 4

However, if a more subdued environment is desired, adding Figure 2. All of these restaurants sufleredfram acoustic defects and all
sound-absorbing material to more than 50% of the wall or having a varying amount afalrsarbing material. Top: Heavy carpet
ceiling surfaces will result in the next tier of treatment, which drapery, and upholstered seating. Center: Mainly reflective materials.
has an E1 of 0.27. Treating 80% or more of the ceiling surface, Bottom: Acoustic ceiling tile (in grid).

Summer 2019 | A.=uuuu=u1-bet-y l 13