Psychoacoustics Flashcards
What is psychoacoustic and the main goal of this science?
The psychology in hearing science. The goal is to investigate how the behavior is resulted from the stimuli.
In psychoacoustics we investigate…
The relationship (F): how the behaviors (Ω) result from the stimuli (S): Ω= F(S), or what is F.
What is the difference between “psychoacoustics” and “Psychophysics”?
Psychacoustics refers to the behavioral consequences of acoustic stimuli, but psychophysics refers to the study of physical stimuli and their interaction with sensory systems.
What are the three properties of sound?
Intensity, frequency contents, temporal pattern
Position of Psychology in neuroscience: (6)
- It is the start and the end point of neuroscience.
- Brain is initially treated like a black box: the concerns are on the input and output: input=stimuli, output=behavioral consequences.
- The black box is then opened to show which brain structures are likely responsible for behavior.
- Hypotheses are proposed to establish F quantitatively.
- Hypotheses are tested, and F is modified via psychological, neurological, molecular experiments, potential mechanisms underneath F is explored
- Theories developed and matured to explain the behaviors and serve people
What are the four functional relationships? (Between S and Ω)
Detection, discrimination, identification, Judging (scaling)
Detection refers to:
determining whether the signal is there or not;
Discrimination is judging:
a difference when two signals are presented
Identification is the ability to:
point out which one is the target signal among other sources
Judging is thought of as:
‘scaling’ in which the response is quantified
What are the corresponding behaviors (Ω) to the sound properties? (4)
Intensity- loudness
Frequency- Pitch
Temporal pattern- Timing
Combination of frequency, and intensity change with time—timbre -Quality
What is considered a high-level process?
Recognition of speech
What are the two big categories for these psychoacoustic studies?
Analytic and Individual
What is the difference between analytic and individual?
Analytic refers to the roles of the individual acoustic parameters (intensity, frequency, and temporal patterns)
Integrative studies look at how the integration of individual parameters relates to our perception.
What is an example of analytic study?
Analytic: how the acoustic parameters are discriminated, identified, and scaled.
What is an example for integration studies? (5)
- Sound localization tasks
- Notion of ‘timbre’
- Integration of frequency components
- Intensity and temporal patterns”
- Auditory perception tasks
Define integration.
It is the process of neurons across different auditory channels, different types of neurons, and different nuclei, excitation versus inhibition, afferent versus efferent.”
What is the difference between a ‘top-down’ and bottom up’ process as it relates to the auditory system?
Top-down means how the experience and knowledge affect what we hear and bottom-up is how what we hear and pick up (the physical feature of sound) affects the perception.
Auditory perception: (2)
- Acoustic image in the complex sound field
- Involves top-down process (experience and knowledge already stored)
What is another word for ‘limen’?
Threshold
What are the three dimensions of auditory ability?
Absolute limen (Detection), Terminal limen, Difference limen (Discrimination)
What is the difference between the three dimensions of auditory ability? (3)
- Absolute limen: lower boundary of detection (i.e. minimum or sensitivity)
- Terminal limen: upper boundary of detection (i.e. maximum or limitation)
- Difference limen: the smallest change in some aspect of the stimulus which can be detected
What is sensitivity as it relates to hearing thresholds?
Absolute thresholds to sound intensity/pressure—the basic target of hearing evaluation (what we do in audiology audiogram)
What are minimum audibility curves?
The sensitivity across frequency range.
What is the frequency range of hearing?
20 to 20000Hz
What is the terminal threshold?
The upper limit also known as the threshold of discomfort/ threshold of pain
What is the dynamic range of hearing?
The threshold between the terminal and minimum audibility curve.
Why do we call it dynamic range?
It is “dynamic” considering the loudness changes as a result of sound level changes
What is loudness?
Loudness is the perception of sound strength, mainly related to sound level, but also changed by many other factors, such as frequency, duration, the existence of other signals, and tested behaviorly
10 dB level change results in ___ times of change in loudness
2
What does dynamic range vary with?
Frequency and the largest at the middle frequency
What is the difference of the curves between the Terminal threshold curve vs. audibility curve?
Terminal threshold curve is flat, while audibility curve is curved.
Briefly, how is the threshold statistically determined?
Not only by guessing but there are multiple trials and the correct percentage.
For “yes/no” method, the criterion is 50%, which does not clearly show this principle.
Explain the variability threshold across individuals with normal hearing in testing.
Thresholds can vary by 20 dB across individuals with normal hearing (i.e. normal hearing range from -10 to 10 dB HL)
What is test re-test reliability and what is it often given as? (2)
*The variation across different tests on the same groups of subjects.
*The normality is often given as a range (i.e., 10-15 dB in hearing threshold)
What does the range 10-15dB depend on for what is obtained when testing hearing?
The range depends on the accuracy of the method and the skill level of the performer.
What kind of (shape) graph is the general absolute threshold?
An open V shape (ie it slopes downward as it approaches the middle frequency (lower threshold) and then goes upward (higher thresholds for the higher frequencies)
What contributes to the general V shape of the graph of the general absolute threshold?
The middle and external ear resonance, and cochlea (by using bone conduction to determine).
How is the cochlea’s contribution tested?
Using bone conduction since is a way to bypass the external and middle ear.
What does MAF and MAP stand for?
MAF is the minimum audible field
MAP is minimum audible pressure
How is the MAF threshold measured?
Speaker and Calibration in an open field
Binaural
SPLs measured with subject absence
How is the MAP threshold measured?
Closed field
Monaural
SPLs measures with coupler.
What is the decibel difference between MAF and MAP and how is it accounted for?
There is a 6dB difference with the MAF having a lower threshold than MAP.
What are three reasons for the 6dB difference?
- MAP method eliminates external ear resonance, resulting in an amplification loss.
- Binaural summation in MAF
- Physiological noises heard in MAP
Why should we need to care about MAF and MAP differences?
Real-ear calibration is not practical in many cases
What is a coupler?
A ‘man made’ cube that is meant to mimic the human ear based on impedance characteristics.
Why is RETSPL measured?
To ensure the reference is equal across different labs.
(Reference Equivalent Threshold Sound Pressure Level)
Which coupler size between 6cc and 2cc is sued for supra-aural earphones, and which is for insert earphones?
6cc for supra-aural (bigger coupler) and 2cc for insert (smaller coupler); Aside from memory aid: Supraaura covers the auricle and inserts as in you insert to the ears.
What are the 3 main applications RETSPL is used for?
1) Reference for speaker/earphone calibration in clinic
2) Establishing hearing level using RETSPL zero point- 0 dB HL;
3) Allowance of noise in the previous two
What is the difference between SPL, HL and SL (briefly, within the scope of this course)?
SPL: reference of the physical sound pressure
HL: reference of hearing thresholds of normal subjects based on RETSPL (reference equivalent threshold sound pressure level)
SL(sensation level): reference of individual hearing thresholds.
When is there more allowance for noise with RETSPL? Why?
When using earphones, they can block out more sound.
This is also why the earphones are better when you are doing a bedside evaluation, that is, an evaluation that is not in the controlled soundproof audio booth but is in a place that has a lot of background noise.
What is the way to say the difference threshold as it relates to intensity?
The JDD (just detectable difference)
What is Weber’s law?
The JDD a law for sensory discrimination.
What is Weber’s law as it relates to intensity?
The slightest intensity difference that can be detected as a function of the amount of intensity
What does a smaller delta l mean?
Smaller delta I mean less of a difference is needed for detection
As in the class example, what will be the delta I (JDD) if the intensity is 1000, and it is known that I= 10 units and the delta I is 0.5 units?
The answer is 50 units
Because 0.5/10 = 0.05, we have Delta I = 0.05*1000 = 50 units (just cross multiplication)
Based on Weber’s law, what was the graphical expectation?
Expect a horizontal line.
What is the intensity discrimination for pure tones?
Both Weber’s fraction and JDD in dB will NOT change with base quantity.
Intensity discrimination for pure tones is ~1 dB (or ~0.3 in deltaI/I) .
Based on the results, what is Weber’s law described as?
Near missed
What did the results show relating to higher sound levels and Weber’s Law? (2)
Better Threshold than what was predicted from Weber’s law.
It slopes downward as in there is a lower delta I or lower JDD
What type of sound follows Weber’s law better?
White noise
How does the intensity discrimination threshold for white noise compare to pure tone?
The intensity discrimination threshold is smaller for white noise than for pure tones.
What are three methods to play the sound for the intensity discrimination task?
Gated pulse tone, continuous tone, and modulating the tone
What are possible confounds for the gated pulse tone and continuous tone?
The gated pulse tone relies on short memory
The continuous tone is influenced by adaptation
Which method is recommended to overcome the gated pulse tone and continuous tone?
The modulation method
Which method is recommended to overcome the gated pulse tone and continuous tone?
The modulation method
Which method has a lower threshold between the continuous pedestal compared to the gated method?
The continuous pedestal (squares) method gives a lower threshold.
Auditory perception: (2)
- Acoustic image in the complex sound field
- Meaning: involving top-down process (experience and knowledge already stored)
What are 3 examples of integration in psychoacoustics?
Timbre
Sound localization
Auditory perception
Describe Timbre:
Quality of a complex sound, integration of frequency components, intensity, and temporal patterns
Describe Sound Localization:
The use of different cues in intensity, time, and spectrum for locating sound signals
Describe Auditory Perception (2):
Acoustic image in a complex sound field
Meaning: involving top-down process (experience and knowledge already stored)
How is the configuration of the audibility curve formed?
By the contribution from external and middle ears
