HLAA Convention 2010 Special: Workshops # 1

[Guest guest]

NVRC News - July 1, 2010

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From Mouth to Ear: Acoustic Architecture, Assistive Listening Devices and

New Room Acoustical Standards

By Bonnie O'Leary, 7/1/10

This workshop was presented by Martha L. , M.S., CCC-SLP, and Dan

Schwartz. Martha presented her part of the program first. She is a

speech-language pathologist who specializes in animal-assisted therapy at

Central Park, Morning Star Elementary School in Bentonville, Arizona.

Martha's focus was acoustics in the classroom and its impact on learning,

especially for children who have hearing loss. Poor classroom acoustics can

cause reduced understanding of speech; deficits in reading and spelling

ability; problems with behavior, discipline, and cooperation; poor

attention; lower levels of concentration; reduced academic achievement; and

interference with children's learning by affecting memory.

All children are affected by poor classroom acoustics. But the problem is

more serious for children with bilateral or unilateral hearing loss, as well

as children who have a temporary hearing loss (e.g., ear infection). It is

a particular problem also for children who have learning disabilities,

auditory processing disorders, and children who are not native English

speakers.

What are good acoustics? According to the Acoustical Society of America,

there is no single, all-encompassing set of criteria that will yield " good

acoustics " for all rooms and uses. " Small classrooms, large lecture rooms,

auditoriums, cafeterias, gyms, all have different acoustical requirements.

To understand how these different spaces should be designed, we must first

familiarize ourselves with a few basic properties of sound. "

Direct sound travels from its source (person speaking) to the listener in a

straight line without being reflected. It is easy for the listener to

understand.

Background noise is any unwanted sound that interferes with what you are

trying to listen to. Background noise in a classroom can include sounds

from the outside, such as traffic, construction, children on the playground

or it can come from other classrooms.

Reverberation is " the persistence of sound in a room once the sound signal

has abruptly ceased, " according to acousticalsurfaces.com.

Sound/surface interaction refers to what happens to the sound signal as it

travels. Some goes through the surface, some is absorbed by the surface,

some is reflected and some is diffused by the surface.

The longer a sound reverberates by bouncing off reflective surfaces, the

higher the degree of distortion of speech sounds. In a classroom, it is

important to have a short reverberation time, since the direct and early

reflection energy makes it possible to understand speech in rooms.

What can be done to help reduce reverberation time? The following

modifications are suggested by the Florida Department of Education:

1) Acoustic ceiling tile to absorb distorted middle and high frequency

noise and improve speech perception ability

2) Soft surfaces on walls: fabric wall hangings, banners, student work,

and hanging plants

3) Carpeting, particularly if it's installed over a pad, to help absorb

excessive reverberation of high frequency consonant sounds and dampening

noise from students and movement of classroom furniture

4) Draperies, blinds or shades to help buffer the reflective surfaces of

windows; double-pane windows to help shield the classroom from additional

outside noise

5) Cork boards help absorb sound; arranging classroom so instruction

takes place away from noise surfaces such as HVAC units, and using

carpet-covered study carrels to reduce noise from equipment or other

students

In Ms. ' experience, her therapy dogs also act as a sound absorbing

medium.

Central Park at Morning Star Elementary School, built in 2005, offers

acoustic ceiling tile, window treatments, and cafeteria ceiling and wall

tile.

Concluding her presentation, Ms. discussed " The Lombard Effect " , first

documented in 1909 by Etienne Lombard, a French otolaryngologist. It refers

to the involuntary tendency of speakers to increase the intensity, rate, and

pitch of their voice when speaking in noisy environments. It causes reduced

speech intelligibility as the overall noise level increases to overcome

background and reverberated noise. Then the children and the teacher

increase their vocal levels, including intensity, rate, and pitch. The

noise level continues to rise, and Ms. assured us it will drive you

crazy!

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