1. Rebecca Reich
May 24 2011

2.  Who am I?
h
 Audio / Acoustics around the clock
d d h l k

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

9. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
• Flexible
• People job
www.mitacs.ca
• Learn new stuff!

10. •$7 500 industry
75 y
$15 000 •$7 500 Mitacs/FQRNT
$10 000 $5000
min for student flexible
•$36 000 industry
$80 000 •$44 000 Mitacs/FQRNT
$10 000 $10 000 $10 000
$20 000
$10 000 $10 000 $10 000 flexible
internships

11. Let’s get started…
Let’s get started

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

13. Particle motion is a function of space
(displacement, amplitude)
and time

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

15. c = 343m/s (air, 20oC)
we INTERPRET sound 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

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

20. sleep
work
work
wake
play

21.  Your alarm‐clock radio: fast facts
f f
06:00
 Why does Boston Acoustics sound better
than Accurian?

23. Looking at an average over a window of time…

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

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

32.  Dynamic compression a reality of modern
f
music recordings (louder is better)
 Causes listener fatigue
l f

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

41. noises off!
ff
22:00