Psycoacoustics Lec 1-8 Exam 1 Flashcards
How is psychoacoustic fundamental to audiology?
•Need to understand how normal system works
•Need to understand the effects of hearing impairment
•Need to understand how hearing aids and cochlear
implants may help hearing
• Behavior is considered the “gold standard”
What is psycho acoustics ! (3)
relationship between acoustic
signals, the auditory system physiology, and the
psychological perception to sound, to explain
1. the auditory behavioral responses of listeners
2. the abilities and limitations of the ear
3. the complex processes that occur inside the brain
What did fechner interested and say?
Interested in the soul, and felt he was studying sensation to studying the soul
Psychophysics
Combing internal world with external world. Ex: physical world link with sensation (taste, hearing, etc)
So the process of physical aspect is manipulate or behavioral ?
Manipulate
So the process of perception aspect is manipulate or behavioral ?
Behavioral
Under physical aspects or manipulate what are the four audiology usage?
Acoustical :
Frequency
Amplitude
Spectrum
Duration
Under behavioral aspects or perception what are the four terms that can be used!
Perceptual:
Pitch
Loudness
Timbre
Perception of time
What the main difference between physical and perception measure?
Physical has precise measurement of physical quantity
So how exactly do we measure perception?
Sensation and perception are inherent arbitrary. Use appropriate methods-> to correct measure not bias, attention and memory
What is psychophysics
Study of the relationship between a physical stimulus (sound) and its perception (hearing)
What is psychoacoustic
A subset of psychophysics: FOCUS on sound and hearing .
Used in audiology,
Audio engineering
Speech synthesis
Hearing aid design
Basic principles of psychoacoustic: sound is processed by the ______ to lead to perception
Auditory system
Measuring _______ allows an understanding of auditory processing
Perception
To understand hearing we have to measure perception
True
Changes to sound changes what we ___
Hear
Acoustics and perception does not have a 1-1 mapping?
True
If we measure sound , can we also measure hearing from it?
NO
What happens if the auditory system changes within norms?
It changes how we hear and perception of sound
How do we measure perception ?
Psychoacoustics requires manipulating acoustic
signals (spectral and temporal characteristics)
– and measuring responses to those changes
– Connecting the acoustic changes to the
perceptual measurements allows inference of
auditory perceptual mechanisms
Changing sound and measuring the change of perception allows an ____________________
Understanding of auditory processing
What are the four common level of measurement of psychoacoustic ?
Detection
Discrimination
Identification
Comprehension
Describe detection
• Detection – often the absolute threshold, the lowest level of sound
that elicits a detection response
• Forms the basis of the audiogram
Describe discrimination
the just noticeable difference between sounds
• The just noticeable difference (JND)
• The difference limen (DL)
• Common: the JND for frequency, the JND for intensity, the JND for duration,
Describe identification
Usually measures percent correct
• Used for speech or musical recognition experiments
• Used in audiometric testing (e.g., word recognition “NU6”)
Describe comprehension
Comprehension – not typically used in psychoacoustics, but is
sometimes used in audiometric testing
What is sound ?
an oscillation of pressure, created by a
vibrating object, that is transmitted through some
medium composed of frequencies within the range of
hearing
Human ear can hear what range!
20-20,000hz!
Sound wave travels ______
Back and forth.
They do not travel themselves
What is compression/condensation
Molecules pushed together (positive amplitude )
What is rare fraction
Molecules in less pressure form (negative amplitude)
Wavelength
Distance between one compression an rare fraction
Does hearing consists of longitudinal or transverse wave?
Longitudinal wave!
P=14.7 describe the pressure of compression and rare fraction
Compression more than 14.7
Rare fraction less than 14.7
The speed of air is
343m/s at 20 degrees
What variables affect the speed of sound?
The medium and the temperature
What two types of materials affect speed of sound?
Elasticity and density
Does speed increase or decrease if density increases?
Decreases
Does speed increase or decrease if elasticity (stiffness) increases?
Increases
Does sound travel after in water?
Yes
Cycle
One complete oscillation
Frequency
per cycle per second
Period
Time of seconds per cycle
Amplitude
Maximum displacement, average displacement. Rms (root mean square)
Phase
portion of a cycle at a arbitrary point
Rms is only true in sins wave?
True
Rms is used to determine ?
Average Intensity (amplitude) in vibration
Rms = peak *
0.707
What is f = and p=
F= 1/p
P= 1/F
What is a phase exactly?
Particular point in the cycle of a waveform within a 360 circle!
Is a phase audible on simpler waves?
No!
If two waves cancel each other out what is called?
Standing wave!
What are pure tone waves called?
Sinusoidal
If not pure tone , then it is a ______wave
Complex
What shapes can sums of sin waves make?
Triangle and square figures
Infinity numbers of sun waves can make _____
Sawtooth wave.
How to convert Ms to s
Divide by 1000
What is Fourier transform?
Any waveform can be decomposed into set of sine waves (with amplitude, frequency and phase)
If the peak on a spectrum is given 5 what is the RMS?
RMS = 5*.707
How does a waveform of harmonics look like on a spectrum
The combination of harmonics on a waveform to a spectrum are noted in Individual lines based on frequency and amplitude
What does a Spectrogram axis consist of?
Time and frequency
What the difference between wide and narrowband spectrogram?
Narrowband can see individual harmonics better. Wide band can see formats more clearer.
Why does time matter in a waveform or spectra ?
Because when duration is longer, the better spectral resolution will be!!! Push button too fast will make a spectral splatter!!!
The greater the vibration in amplitude, more force in the _____ and higher ______
Medium, pressure
Example: 20-30db how much louder would it be?
10 times louder
Example: 50-70db how much louder?
100 times louder!
What was Craig butler record of sound?
181.1!!!!
How do we scale decibels by what solution?
By log scale and ratio!
What are two reasons for using log scale??
- More manageable to compress large numbers
- Fechner law- log fashion of perception relates to physical stimuli
What is linear vs log scale. What do we use!
Log scale!! (10, 10^1, 10^2)
Linear (1,2,3,4 or 2,4,6)
Why is decibels a relative measurement?
It is a relative measurement because decibeles are in a ratio scaling not a absolute measurement!!!
How many bel is 10 decibels
1
What is the DB IL equation?
10 * 10log 10(1m/1r)
What is 60 HL vs SL
Hearing level- above the lowest point a person can hear
Sensation level- above the lowest that I can hear
Intensity = to what?
Pressure^2 (easier to measure)
How does the decibel scale relate to audiology? (3)
Relevant for perception
Based on human hearing
Compres scale
In DB measurements, change in intensity is used in _____ and change in pressure is used in ____
- Audiogram
- Hearing aids
What does 0dB mean?
Means that the intensity measurement and reference are equal to each other. Does not mean no sound. Basically a ratio of 1. Can have negative sound level!
3 DB = double
Sound power!!! (Two things!)
6DB = double
Sound pressure (distance!)
10 dB= double loudness level?
True
What is SIL
Sound intensity level - level of sound relative to a fixed standard
What is SPL
Ratio of pressure amplitude to a reference pressure
A pressure wave transmitted _____
Outwards in all direction, all the same distance from the point
What is the most basic auditory stimuli?
Pure to e
Pure tone is used to get frequency specific measurement
True! (One frequency and one amplitude in pure tone) (one button called)
How do we make spectral changes by ?
If we make temporal changes in a frequency specific sound
How to check the bandwidth to see spectral splatter?
2/distance
How much does the outer ear amplify?
2000-3000hz
Middle serves as ? And amplify?
Impedance matched between air and fluid within cochlea
800-1200hz
How much does the OE and ME combine to amplify ?
30-40 db from 800-3000hz
What happens if the OE occlude?
Diminish amount of amplification.
Middle is stiffen?
Otitis media/otosclerois =low frequency loss!
Mass increase in ME, what happens?
Otosclerois
Also high freq loss!
In the inner ear, sound form a _______ wave
Traveling wave on the BM
Three rows of OHC do what
Amplify vibration movement on BM
Damage alters amount and spread vibration on BM
One row of inner hair cells do what
Send signal to higher auditory center (brain)
Damage alter integrity of signals to higher auditory center!
Spontaneous rate Abv
SR
Auditory nerve has three fiber types (type 1 95% and IHC)
True
Low threshold has high SR and signal detection near threshold
Yes! True
Middle threshold
Low medium SR
High threshold
Low SR
Signal detection in noise
What are two psychophysical method?
Thresholds -limits of sensitivity
Scaling: ordering and distributing stimuli along a perceptual dimension
What is pychsometric function?
The relationship of signal of detection and percentage of correct identification 70-80%
The yes or no task, describe
consists of an observation
interval and response interval
• observation interval: the time epoch in
which a subject listens for a stimulus
• defined – subjects knows when to listen
(e.g., indicated by lights)
• Or undefined – subject does not know
when to listen (e.g., random stimulus
presentation)
• response interval: the time epoch in
which a subject is expected to respond
• Subject says “yes I heard a sound” or “No
I did not hear a sound”
• Will be either correct or incorrect
What are three ways to estimate threshold?
Constant stimuli
Limit
Adjustment
What is constant stimuli, and it’s pro and cons
Different values, in random order of trials! Threshold at arbitrary performance level (50-100).
Randomly selected signal level
Repeat trail over and over and random level again and again
Récord percent correct or percent detection !
Pro:
Used to measure entire pm fuction
Used preset signal level
Easy to administer
Cons:
Time consuming!
Preset finding not always easy!
Method of limits describe cons and pros
Level where you THINK they can hear and lower and lower and lower!
Then no, go up until audible
Has possible anticipation effects.
No-> increase signal
Yes-> decrease signal
Effective pro! At small number of trails! B/c concentrated around threshold.
No need to know threshold with designing experiment
Cons
Spurious threshold may be obtain (fake!) (could say yes just because)
Adjustment
Basically the subject hold down a button until they can hear a sound. Very easy to fake! Called Bekesey tracking
Pros
Super easy
Appealing
Cons:
False readings
Modified method of limits does what
Combine ascending and descending trails of method of limits . Modified huggson west lake !
10db-5db up
2/3 responses
85-95%
Adaptive staircase works how?
2 down, 1 up. Or 3 down 1 up
Based on average reserval
71%
