Download ASKK-DHH Listening E..

Dodo Youyou Hearhear Meme?
The Listening Environment
Molly Lyon, M.A., CCC-A/SP
LSLS AVEd
Via Christi Hospitals
January 21, 2011
Objectives
 Participants
will understand the concept of
acoustic access and its importance in
developing listening skills
 Participants will become familiar with the
environmental factors affecting audition
 Participants will learn about the application
of using FM technology in children
Listening in Children
Some Food for Thought…
 Children
do not know what they don’t hear
 Children do not expend the mental energy
to comprehend a degraded, low intensity
speech signal comprised of vague,
unfamiliar words
 They do not “go back” in auditory space
and try to figure out what they didn’t hear
 Children
do not hear and process oral
language at adult-like levels until around
age 13
 Language acquisition is a work in progress
 As language and worldly knowledge
increases the less reliant we are on
precision hearing
 Adult: 10% earwork and 90% brainwork
 Child: 90% earwork and 10% brainwork
Transparency
 For
young listeners, the speech signal
must be crystal clear, or “transparent”
before true and optimal comprehension
and language growth can occur
 The
listening environment is critical to the
development of auditory skills
Prerequisites
 Assuming
the child has been fitted with
HA/CI
 Assuming the technology is programmed
optimally
 Assuming the child is wearing the HA/CI
all waking hours
 Little ears are now ready to listen, but…
A Moving Target
HEARING LOSS is the only handicapping
condition in which the disabling effect is
in a constant state of flux.
The negative impact of hearing loss can
range from being nearly nonexistent to
completely rendering an individual’s
ability to use audition useless.
What is Acoustic Access?
 The
degree to which spoken language is
audible to a child
 Goal: 100% of the speech signal is
audible 100% of the day
Acoustic access is under
ADULT CONTROL
Environmental Factors Affecting
Acoustic Access
NOISE
DISTANCE
REVERBERATION
Background Noise
 Speech-To-Noise
ratio (S/N) is critical
 Relationship between the primary signal
(speech) and background noise.
 Noise sources include other talkers,
heating or cooling systems (HVAC),
timers, bells, alarms, computer hums,
CD’s, radios, TV’s, wind, pets, etc.
 Homes are typically quieter than
classrooms
Allowable Signal-to-Noise
Ratios
 Adults
with normal hearing require a S/N
ratio of +6 dB (approximately twice as loud
as background noise)
 Children
with hearing loss require a S/N
ratio of +15 to +20 dB
Distance
 Sound
is degraded as it is propagated
through space
 Rapid
Speech Transmission Index (RASTI
study, Leavitt and Flexer, 1991)
 Integrity of a speech signal was measured
at 17 different distances
RASTI Results
4 feet – RASTI score 83%
(critical speech information lost = 17%)
 Approximately
 Approximately
25 feet – RASTI score =
45%
 Perfect
RASTI score was only able to be
obtained at a distance of 6 inches from the
RATSI transmitter.
Distance and Decibels


Double the distance,
lose 6 dB of intensity
Every decibel is
critical to children with
hearing loss
Distance
Decibel
6”
60dB
12”
54dB
2’
48dB
4’
42dB
8’
36dB
16’
30dB
32’
24dB
Reverberation (Echo)
DEFINITION:
 The time it takes in seconds from the
moment a sound is stopped until the
sound level has diminished 60dB.
Affects of Reverberation
 Normal
hearing adults can adequately
discriminate speech in reverberations
times of .75 to 1 second
 Children with hearing loss require
reverberation times of .5 seconds
Anechoic chamber = 0 seconds
Typical classroom = 1.6 seconds
Reverberation Issues
 Reverberant
sounds mask high frequency
sounds
 Greater absorption of high frequency than
low frequency sounds
 Elongations of vowels
 Smears transitions
 Eliminates silent gaps
Boothroyd Demonstration
 Distance
 Noise
 Reverberation
Boothroyd, A., Phonic Ear Sound field
tutorial 1.4a Room Acoustics and Speech
Perception: The Basics
FM Use in Children
 Significantly
improves and maintains
speaker’s voice over background noise
 Eliminates
 Reduces
 Child
effects of distance
effects of reverberation
is able to receive consistent speech
signal
Listen …
Hearing Aid only
Hearing Aid + FM
Soundfield Demonstration
FM mic only
Bibliography




American National Standards Institute. (2002).
Acoustical performance criteria, design requirements,
and guidelines for schools (S12.60-2002). New York:
American National Standards Institute (ANSI S12.60).
Boothroyd, A. (2004). Room acoustics and speech
perception. Seminars in Hearing, 25(2), 155-166.
Cole, E.B., and Flexer, C. (2008). Children with hearing
loss: Developing listening and talking birth to six. San
Diego, CA: Plural Publishing.
Crandall, C.C., Smaldino, J.J. & Flexer, C. (eds). (2005).
Sound-field amplification: Applications to speech
perception and classroom acoustics (2nd ed.). Clifton
Park, NY: Thomson Delmar Learning.



Davis, J. (Ed.). (1990). Our forgotten children: Hard-ofhearing pupils in the schools. Bethesda MD: Self Help
for Hard of Hearing People.
Flexer, C. (2004). The impact of classroom acoustics:
Listening, learning and literacy. Seminars in Hearing,
25(2), 131-140.
Northern, J.L., & Downs, M.P. (2002). Hearing in
children (5th ed.). Baltimore: Lippincott Williams &
Wilkins.