2. Who am I?
h
Audio / Acoustics around the clock
d d h l k
3.
4. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
B. Eng, electrical, Minor Arts
NRC Women in Engineering and Science scholarship
g g p
• classroom and concert hall acoustics
S.M., Media Arts and Sciences
Cochlear implants
hl l
how do they sound when music plays through them?
5. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Programming 1’s and 0’s
Programming user software
Customer technical
support
6. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
One year in Copenhagen, DK
Customer technical support
7. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Customer technical support (five months)
C h i l (fi h )
Manager, customer technical support team
China, Japan, Canada
12. Sound is a form of energy (like electricity or
f f
light)
Sound is made when air molecules vibrate
d d h l l b
and move in a pattern waves
Animation courtesy of Dr. Dan Russell, Kettering University
14. Longitudinal wave:
particle motion is parallel to motion of disturbance
created by moving object
Wave causes areas of compression (high
pressure) and rarefaction (low pressure). We
) d f i (l ) W
call this PRESSURE waves
16. Frequency:
F
how often the particles are moving back and forth:
# of complete back‐and‐forth vibrations
p
of a particle of the medium Hertz:
per unit of time # cycles per second
20Hz – 20 000Hz
H H
Sensation of frequency = pitch
17.
18. Greater amplitude of disturbance causes
G li d f di b
greater displacement (amplitude) of particles
More amplitude more energy
Intensity = power/area (Watts/m2)
Move away from sound ,intensity decreases
(inverse square)
Humans can detect as low as 1*10‐12 W/m2, ,
and as high as 1 billion times this!
Due to large range: dB
1*10‐12 W/m2 = 0 dB
d
24. Why does everyone sound good singing in the
Wh d d d i i i th
shower?
06:15
5
ACOUSTICS: study of waves in a medium
Direct, Reflected, Refracted, Absorbed
fl d f d b b d
25. Hard surfaces
f
little sound absorbed (ceramic tile)
many reflections reverberation
~50ms is threshold for
i th h ld f
hearing echo
26. Small space
accumulation of reflections
increases volume
you sound more powerful!
Resonant cavity
Shower stall dimensions
cause standing waves at
d
low frequencies; vocals in
this range will be boosted
27.
28. Car stereo acoustics
08:00
“dead” sound environment, depends on materials
(leather vs. upholstry)
transitory (windows open vs. closed)
loud: riding the volume knob
29. Single‐band compressor, loud bass information
l b d l db f
modulates gain of the entire audio signal
suboptimal maximum perceived loudness & gain
pumping
30. Listening to iPod
[Portnuff] listening to earbuds for 90 minutes/day at
80% volume is probably safe for long‐term hearing
(softer is better: you can safely tune in at 70%
volume for about 4½ hours a day.)
volume for about 4½ hours a day )
~ one in five teenagers had some kind of hearing loss in
2005 2006, up from 15% of teenagers in the late 1980s and
2005‐2006, up from 15% of teenagers in the late 1980s and
early 90s, according to a study of nearly 5,000 people age
12 to 19 published in the Journal of the American Medical
Association.
31. The maximum exposure time for unprotected
Th i ti f t t d
ears per day at 90 dB is 8 hours.
For every 5 dB increase in volume the maximum
For every 5 dB increase in volume, the maximum
exposure time is cut in half.
95
95 dB = 4 hours
4
100 dB = 2 hours
110 dB = 30 minutes
120 dB = 7.5 minutes
Apple set 100dB limit in Europe, still 115dB in
USA
34. 08:45
45
In general, noise levels above 45‐50 dB(A) tend to be
I l i l l b dB(A) d b
disturbing
Speech Intelligibility Index (SII): how well speech can be
understood in the presence of noise.
p
range: 0 (perfect privacy) to (perfect intelligibility)
Theatres and auditoriums need high SII values, but offices
and other private locations need low SII
SII <= 0.2 gives employees speech privacy and blocks most
SII <= 0 2 gives employees speech privacy and blocks most
acoustical distractions
35. Ceiling and floor
C ili d fl
Partitions (partial‐height screens)
Workstation and Occupant Orientation
Lighting fixtures (flat vs grill)
Noise Masking System
36. Noise‐cancellation headphones
N i ll ti h d h
Active vs. Passive
09:00
9 Active:
▪ produce “anti‐noise”
▪ require battery
▪ cancel low‐frequency continuous
cancel low frequency, continuous
sound actively, high‐frequency through
design
Passive
▪ physical block; works over wide range
▪ no battery
▪ weaker bass response (due to speaker
size)
37. Your hearing… getting old…”eh?”
18:00
• outer/middle ear
conductive
• often reversible
• inner ear
sensorineural • not reversible
• can be age‐related
b l t d
38. Symptoms
Certain sounds seem overly loud
Difficulty hearing things in noisy areas
High‐pitched sounds such as "s" or
"th" are hard to distinguish from one
another
Men's voices are easier to hear than
womens.
Other people's voices sound mumbled
p p 20% over 65
or slurred
Ringing in the ears 40% over 75
“I hear but I can’t understand”
80% nursing home
residents
39. Not just amplifiers
f
ex. frequency translation
Adapt to environment
cocktail party effect
Connected
bluetooth
bilateral communication
40. 36,000 people world‐
36 000 people world
wide received cochlear
implants over the last
two decades.
t d d
FDA‐approved 1985
(adults), 1990 (children)
Ad lt
Adults can now be
b
considered candidates if
they have severe‐to‐
profound hearing loss
f d h i l
and understand less
than 50% of sentences
spoken to them
k t th
violin violin, processed