physics 1251 the science and technology of musical sound
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Physics 1251 The Science and Technology of Musical Sound. Unit 2 Session 14 MWF Human Perception: Loudness. Physics 1251Unit 2 Session 14 Human Perception: Loudness. Foolscap Quiz: A sound has an intensity of 0.005 W/m 2 . What is the Sound Intensity Level (SIL) in dB? - PowerPoint PPT PresentationTRANSCRIPT
Physics 1251Physics 1251The Science and The Science and
Technology of Musical Technology of Musical SoundSound
Physics 1251Physics 1251The Science and The Science and
Technology of Musical Technology of Musical SoundSound
Unit 2Unit 2
Session 14 MWFSession 14 MWF
Human Perception: Human Perception: LoudnessLoudness
Unit 2Unit 2
Session 14 MWFSession 14 MWF
Human Perception: Human Perception: LoudnessLoudness
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Foolscap Quiz:Foolscap Quiz:A sound has an intensity of 0.005 W/mA sound has an intensity of 0.005 W/m22. . What is the Sound Intensity Level (SIL) in What is the Sound Intensity Level (SIL) in dB?dB?
Pass the sheet to your left when you finish. Pass the sheet to your left when you finish. Please do not use your notes. Thank Please do not use your notes. Thank you!you! SIL = 10 Log ( I / ISIL = 10 Log ( I / Ithreshold threshold ))
SIL = 10 Log ( .005/ (1 x10 SIL = 10 Log ( .005/ (1 x10 -12-12))))
SIL = 10 Log ( 5 x 10SIL = 10 Log ( 5 x 1099 ) = 97 dB. ) = 97 dB.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
11′ Lecture:′ Lecture:• LoudnessLoudness is the magnitude of the sensation is the magnitude of the sensation
produced by a sound; the “amount” of produced by a sound; the “amount” of sound.sound.
• Loudness (in Loudness (in sonesone) is how many times larger ) is how many times larger (or smaller) the sensation is judged to be, (or smaller) the sensation is judged to be, relative to a tone of SIL=40 dB at 1000 Hz.relative to a tone of SIL=40 dB at 1000 Hz.
• Loudness LevelLoudness Level (in phon) is equal to the SIL (in phon) is equal to the SIL at 1000 Hz that produces the same at 1000 Hz that produces the same magnitude of sensation.magnitude of sensation.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
The Human Ear is a “non-linear The Human Ear is a “non-linear Sensor”Sensor”PhysicsPhysics ⇒ ⇒ Physiology Physiology
⇒⇒PerceptioPerceptionn
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Human Aural Response:Human Aural Response:
• Intensity Intensity →→ LoudnessLoudness
• Frequency →Frequency → PitchPitch
• Vibration Recipe Vibration Recipe →→ TimbreTimbre
Frequency Frequency
Vibration Vibration
RecipeRecipe IntensityIntensity
Vibration recipeVibration recipe
IntensityIntensity
FrequencyFrequency
But…But…
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
““Resonant” Frequency vsResonant” Frequency vs
Location on Basilar Location on Basilar MembraneMembrane
20 kHz20 kHz
20 20 HzHz
Range of Range of Maximum Maximum SensitivitySensitivity
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
The Density The Density of Hair Cof Hair Cells (HC)ells (HC)
varies with distancevaries with distance
from the stapes.from the stapes.
Fewer Fewer HCHC
Fewer HCFewer HC
More HCMore HC
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Fletcher- Munson DiagramFletcher- Munson Diagram
Fletcher and Munson (1933) Fletcher and Munson (1933) J. Acoust. Soc. Am. J. Acoust. Soc. Am. 55, 82-108, 82-108Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
101020203030404050506060707080809090
100100110110120120130130
Loudness Loudness (phon)(phon)
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
80/2080/20The The Fletcher-Munson DiagramFletcher-Munson Diagram is a plot of is a plot of the SIL (in dB) versus frequency for the the SIL (in dB) versus frequency for the SIL required to produce an equal SIL required to produce an equal sensation as that produced at 1000 Hz. sensation as that produced at 1000 Hz.
80/2080/20The contours are of equal The contours are of equal loudness levelloudness level..
80/2080/20The unit of loudness level is the The unit of loudness level is the phonphon..
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Fletcher- Munson DiagramFletcher- Munson Diagram
Fletcher and Munson (1933) Fletcher and Munson (1933) J. Acoust. Soc. Am. J. Acoust. Soc. Am. 55, 82-108, 82-108Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
101020203030404050506060707080809090
100100110110120120130130
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Auditory Demonstration #6Auditory Demonstration #6Houstma and RossingHoustma and Rossing
Institute for Perception ResearchInstitute for Perception Research (IPO)(IPO)Einhoven, The NetherlandsEinhoven, The Netherlands
&&Acoustical Society of AmericaAcoustical Society of AmericaTrack 17,18Track 17,18
Count the number of tones you thatCount the number of tones you that
can hear at each of the following can hear at each of the following frequencies:frequencies:
125, 250, 500, 1000, 2000, 4000, 8000 Hz.125, 250, 500, 1000, 2000, 4000, 8000 Hz.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Using the Fletcher- Munson DiagramUsing the Fletcher- Munson Diagram
Determine the SIL necessary to Determine the SIL necessary to have a Loudness Level of 70 have a Loudness Level of 70 phon at 200 Hz, 2000 Hz and phon at 200 Hz, 2000 Hz and 10,000 Hz.10,000 Hz.
Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
4040
9090
1010
3030
6060
8800
110110
130130
2020
5050
7070
100100
120120
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Using the Fletcher- Munson DiagramUsing the Fletcher- Munson DiagramDetermine the SIL necessary to have a Loudness Determine the SIL necessary to have a Loudness
Level of 70 phon at 200 Hz, 2000 Hz and 10,000 Level of 70 phon at 200 Hz, 2000 Hz and 10,000 Hz.Hz.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Fletcher- Munson DiagramFletcher- Munson Diagram
Fletcher and Munson (1933) Fletcher and Munson (1933) J. Acoust. Soc. Am. J. Acoust. Soc. Am. 55, 82-108, 82-108Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
101020203030404050506060707080809090
100100110110120120130130
Equal Equal LoudnessLoudness (70 phon) (70 phon)
200 Hz—70 200 Hz—70 dBdB2 kHz—70 2 kHz—70 dBdB10 kHz—75 10 kHz—75
dBdB
Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
4040
9090
1010
3030
6060
8080
110110
130130
2020
5050
7070
100100
120120
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Using the Fletcher- Munson DiagramUsing the Fletcher- Munson DiagramUsing the F-M Diagram determine the Loudness Using the F-M Diagram determine the Loudness
Level of an 80 dB tone at 100 Hz, 400 Hz and Level of an 80 dB tone at 100 Hz, 400 Hz and 8000 Hz.8000 Hz.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Fletcher- Munson DiagramFletcher- Munson Diagram
Fletcher and Munson (1933) Fletcher and Munson (1933) J. Acoust. Soc. Am. J. Acoust. Soc. Am. 55, 82-108, 82-108Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
101020203030404050506060707080809090
100100110110120120130130
73 73 phonphon81 phon81 phon72 phon72 phon
Loudness Loudness (phon)(phon)
80 dB
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Fletcher- Munson DiagramFletcher- Munson Diagram
Fletcher and Munson (1933) Fletcher and Munson (1933) J. Acoust. Soc. Am. J. Acoust. Soc. Am. 55, 82-108, 82-108Frequency (Hz)Frequency (Hz)
SIL SIL (dB)(dB)
101020203030404050506060707080809090
100100110110120120130130
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Since the Loudness Level for a given frequency can be Since the Loudness Level for a given frequency can be approximated by a linear function of the Intensity approximated by a linear function of the Intensity Level,Level,
Thus:Thus:
LL LL ≈ ≈ AAff (SIL – SIL (SIL – SILthreshold threshold ),),
80/2080/20One of the settings of a Sound Level Meter One of the settings of a Sound Level Meter (filter switch “A”) modifies the calibration of (filter switch “A”) modifies the calibration of the instrument to account for the frequency the instrument to account for the frequency dependence of human hearing.dependence of human hearing.
80/2080/20The Sound Level is reported then as “dBA.”The Sound Level is reported then as “dBA.”
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Sound Level MeterSound Level Meter
• Measures Measures
Sound Intensity Level Sound Intensity Level
(SIL) in dB(SIL) in dB
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
LoudnessLoudness
80/2080/20 A subjective measure of the magnitude A subjective measure of the magnitude of auditory sensation is called of auditory sensation is called LoudnessLoudness and is measured in and is measured in sonesone. In this system, . In this system, one listens to two sounds and judges one listens to two sounds and judges how much louder or softer a test sound how much louder or softer a test sound is compared to the referenceis compared to the reference..
For example, a sound of 2 sone sounds twice as For example, a sound of 2 sone sounds twice as loud as a tone of 1 sone.loud as a tone of 1 sone.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Auditory Demonstration #7Auditory Demonstration #7Houstma and RossingHoustma and RossingInstitute for Perception ResearchInstitute for Perception Research (IPO)(IPO)Einhoven, The NetherlandsEinhoven, The Netherlands
&&Acoustical Society of AmericaAcoustical Society of AmericaTrack 19,20Track 19,20
Estimate how loud each of the sound samplesEstimate how loud each of the sound samples is, compared to the reference sound is, compared to the reference sound
sample. sample.
The reference is presented first along with the The reference is presented first along with the loudest and softest sounds. loudest and softest sounds.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Loudness ScalingLoudness Scaling
Loudness L Loudness L ∝∛ I ∝∛ I
80/2080/20Thus, an eight (8) singer ensemble Thus, an eight (8) singer ensemble
sounds about twice (2x) as loud as a sounds about twice (2x) as loud as a
soloist. Because soloist. Because ∛∛8 = 2. 8 = 2.
Likewise, a choir of sixty-four (64) sounds Likewise, a choir of sixty-four (64) sounds
about four (4x) times louder than a soloist. about four (4x) times louder than a soloist.
∛∛64 = 4.64 = 4.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Summary:Summary:• LoudnessLoudness is the magnitude of the is the magnitude of the
sensation produced by a sound; it is sensation produced by a sound; it is measured in sone.measured in sone.
• Loudness LevelLoudness Level (in phon) is equal to the (in phon) is equal to the SIL at 1000 Hz that produces the same SIL at 1000 Hz that produces the same magnitude of sensation.magnitude of sensation.
• Loudness increases approximately with Loudness increases approximately with the the cube rootcube root of intensity. of intensity.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Summary:Summary:• The loudness depends on The loudness depends on
frequency.frequency.
Physics 1251Physics 1251 Unit 2 Session 14Unit 2 Session 14Human Perception: LoudnessHuman Perception: Loudness
Examination 1Examination 1Physics 1251.001 2003C
Examination #1
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F D C B A