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Sound Facts
Sound and Vibration
Soundwaves
Frequency
Pure Tones
Harmonics
Complex Sounds
Frequency and Hearing
Sound Amplitude, Intensity, Power
Sound Pressure Level (SPL)
Decibels
Decibel Levels
Human Hearing Curves (dB v. Hz)
ÇANKAYA UNIVERSITY – DEPARTMENT OF INTERIOR ARCHITECTURE
INAR 326: ARCHITECTURAL ACOUSTICS
ASSIST. PROF. DR. PAPATYA NUR DÖKMECI YÖRÜKOGLU
CHAPTER 1: WHAT IS SOUND? BASIC PRINCIPLES
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Sound Facts
n  Needs
a medium (particles) to travel
n  Cannot
n  Speed
travel in vacuum, or space
of sound is around 1,230 km/hr or 340m/s
n  Travels
3 times faster through water than air
n  Travels
10 times faster through granite than air
n  Travels
15 times faster through steel than air
n  When
whales communicate with each other under water,
their sound can travel up to 800 km in the ocean
n  Dolphins
can hear underwater sounds from 24km away
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound and Vibration
n 
Sound is a vibration in an elastic
medium such as;
n  Air
n  Water
n  Building materials
n  Earth
n 
Sound travels in a medium
through back and forth vibration
of the particles as waves
Tuning fork: Diyapozon, akort çatalı
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
* http://www.physicsclassroom.com/class/sound/
February 21, 2017
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Soundwaves
Rarefaction: Regions of low particle density
Compression: Regions of high particle density
Crest (peak): Highest point/maximum value of the wave within a cycle
Trough: Lowest point/minimum value of the wave within a cycle
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Soundwaves
Wavelength: Distance between 2 crests, troughs or points where
one cycle is completed
Cycle: Each complete vibration of a particle from its starting
position to a maximum distance and back to origin.
More explanation:
https://www.youtube.com/watch?v=RVyHkV3wIyk
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Frequency
n Number
n Its
of cycles completed in a second
unit is; Hertz (Hz)
n  1
Hertz = 1 vibration/second so;
n  If a particle of air undergoes 1000 longitudinal
vibrations in 2 sec, then the frequency of the wave
would be 500 vibrations per sec.
n  Speed
= frequency x wavelength
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Frequency
•  Different frequencies have differing wavelengths
that are effected by the dimensions of the
enclosure
•  Wavelength of;
•  100 Hz = 3.000.000 m
•  1000 Hz = 300.000 m
•  10.000 Hz = 30.000 m
http://www.csgnetwork.com freqwavelengthcalc.html
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Pure Tones
n  Vibration
n  Have
produced at a single frequency
sinusoidal waveforms as; sine or cosine waves
n  Pure
tones with the sinusoidal waveforms are unpleasant
to human ear and may cause noise-induced hearing loss
at even low volumes
n  Symphonic
music consists of numerous tones at different
frequencies and pressures
Some Examples:
http://fearofphysics.com/Sound/sounds.html
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Harmonics
n  Integer
multiples of the frequency, f (ex: 2f, 3f, 4f…)
and are periodic with the fundamental frequency
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
Listening Lab:
http://www.artsalive.ca/en/mus/instrumentlab/
strings.html#violin
http://www.musictechteacher.com/
music_learning_theory/music_instruments.htm
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ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
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February 21, 2017
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Complex Sounds
n 
n 
Most sounds in everyday life is complex consisting of
varying frequencies and pressures.
Speech, traffic noise, TV…
High Sound Pressure
(loud sounds)
Low Sound Pressure
(soft sounds)
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Frequency and Hearing
n 
Human hearing (audible) range is between;
Infrasound < 20 Hz – 20.0000 Hz < Ultrasound
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound;
Amplitude, Intensity, Power
n  Both
amplitude and intensity are related to
sound's power.
n  All
three of these characteristics have their own
related standardized measurements.
http://www.indiana.edu/~emusic/acoustics/amplitude.htm
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Amplitude
(Genlik)
n  Amplitude
is the objective measurement of the degree of
change (positive or negative) in atmospheric pressure (the
compression and rarefaction of air molecules) caused by
sound waves.
n  Sounds
with greater amplitude will produce greater
changes in atmospheric pressure from high pressure to low
pressure.
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Amplitude
(Genlik)
n  Amplitude
is directly related to the acoustic energy or
intensity of a sound
n  Amplitude
is measured in the amount of force applied
over an area
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound Intensity(şiddet) and
Power (güç)
n  Intensity
can be measured as watts per square meter
n  Intensity
can be seen as amplitude over time over an
or w/m2
area
n  The
power of the original sound source along with
distance of measurement from the sound source
combine to form the intensity
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound Intensity(şiddet) and
Power (güç)
Inverse Square Law
•  Every time distance from sound source is doubled
intensity of sound reduces by a factor of 4.
•  There is an inverse square relationship between
the sound intensity and the distance from the
sound source.
http://www.feilding.net/sfuad/musi3012-01/html/lectures/003_sound_II.htm
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound Intensity(şiddet) and
Power (güç)
http://www.feilding.net/sfuad/musi3012-01/html/lectures/003_sound_II.htm
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Sound Pressure Level (SPL)
n  Logarithmic
measure of the sound pressure based
on a reference value.
n  The
standard reference sound pressure in air is 20
μPa (micropascal) and considered as the
threshold of human hearing at 1kHz.
n  Measuring
unit is Decibels (dB).
n  Different
dB filters are used for varying sound
source analysis depending on the frequency scope
of the source.
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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with sound pressure and sound intensity
http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
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February 21, 2017
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Decibels
n  Bel
unit named after; Alexander Graham Bell.
n  First
used to relate the intensity of sound to an
intensity level corresponding to the human hearing
sensation.
n  Decibel
is a logarithmic measuring unit that means
summing is different than regular math systems.
n  So, 10dB
+ 10dB ≠ 20dB then,
what is the value???
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Decibels
10dB+10dB=13dB
10dB+11dB=13.5dB
10dB+12dB=14dB
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
10dB+13dB=15dB
10dB+20dB=20.5dB
10dB+21dB=21dB
February 21, 2017
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SPL – Decibel
Weightings; A, B, C, Z
§  dB(A) Filters out more bass than the
others. It is very useful for eliminating
inaudible low frequencies.
§  dB(B) and dB(C) Does not filter out as
much of the lows and highs as dB(A)
weighting.
§  dB(Z) Is a flat frequency response of 10Hz
to 20kHz ±1.5dB. This response replaces
the older "Linear" or "Unweighted"
responses.
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/acont.html
http://www.noisemeters.com/help/faq/frequency-weighting.asp
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Human Hearing Curves (dB v. Hz)
https://www.youtube.com/watch?v=qNf9nzvnd1k
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Decibel Levels
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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February 21, 2017
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February 21, 2017
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Let’s Listen
n 
http://fearofphysics.com/Sound/sounds.html
n 
http://www.artsalive.ca/en/mus/instrumentlab/strings.html
n 
http://www.musictechteacher.com/music_learning_theory/
music_instruments.htm
ÇANKAYA UNI-INAR 326-WEEK:2-P.N. DÖKMECİ YÖRÜKOĞLU
February 21, 2017
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Thank you!
Have a great week…
J