MMB-MusicPerception_1b_Psychoacoustics Flashcards
- What does psychoacoustics aim to do?
Psychoacoustics aims to quantify the relationship
between an auditory stimulus and its percept
- Describe two steps to psycho-acoustical experiments:
- Vary stimulus parameter (eg intensity or frequency) and
- Observe how human perception / responses change
- What 5 elements make up Components of psycho-acoustical experiments?
- Stimulus
- Task
- Mehtod
- Analysis
- Measure
- Give an example to detrmine hearing thresholds with Method of limits.
Stimuli: Pure sine tones
• Task: Forced-choice task‘Do you hear it?’ (Y/N)
• Method: In-/decrease intensity for subsequent trials
(Method of Limits)
• Analysis: Record for each intensity level whether
stimulus was detected or not and compute average
(detection rate) for each level
• Measure: Hearing Threshold, i.e. intensity level at given
detection rate (e.g. 50% or 75%)
- What is the reality of detecting a stimulus multiple times?
There is a variabliity:
Sometimes you hear it; sometimes you don’t due to various sources of error, e.g. ‘variability of brain activity’ (Solomon, 1900) or ‘of perceptual processes’ (Thurstone, 1927)
- Describe the Method of Limits.
In ascending method of limits, some property of the stimulus starts out at a level so low that the stimulus could not be detected, then this level is gradually increased until the participant reports that they are aware of it.
The decending method of limits reverses this.
- What is the detection threshold?
An detection thershold or **absolute threshold **is the level of intensity of a stimulus at which the subject is able to detect the presence of the stimulus some proportion of the time (a p level of 50% is often used)
- Discuss problems with the Method fo Limits.
• Trials are given in a systematic order and participants
might form expectations (errors of habituation and
expectation)
• Participants might have individual bias to respond ‘yes’
or ‘no’
- Describe
2-alternative forced choice task which is an alternative to **Method of limits. **
• Participant needs to detect feature in one of two stimuli
presented and responds ‘1’ or ‘2’
• Feature can be e.g. mistuning, specific frequency in
complex sound, higher pitch.
• Stimuli with and without feature are presented randomly
at position 1 or 2
- 3-Alternative forced choise task (3AFC) is known as what?
- 3AFC (‘odd-one-out’) paradigm: Present more than 2 stimuli and participants indicate which one was different to the others (i.e. carried the feature)
- Other variants: ‘same-different’ response, match to sample response
- A number of alternative choice tasks (nAFC)
Draw a graph of possible combinations.
- Describe the adaptive method: Staircase.
•Parameter of interest (eg intensity) is varied across X
levels
•Order of presentation of these levels is determined by the
participant’s response
– Starts easy, gets harder as long as performance correct
– Incorrect response trial leads to a ‘reversal’: the subsequent trial is one level easier
– Set maximum number of ‘reversals’
•Threshold determined by finding the average level of the
last X reversals
- Draw a diagram illustrating a siple up-down staircase
- Describe **Running Fits. **
•Select stimulus at most likely threshold level, based on
responses so far (procedures MLP, PEST, QUEST)
- Give an example of a complex tone frequency discrimination thershold experiment. List the following stages.
- Stimuli
- Task
- Method
- Analysis
- Measure
- Stimuli: Complex sine tones
- Task: 3AFC ‘which tone is highest?’ (1,2,3)
- Method: running fit stimulus selection at perceptual threshold
- Analysis: Fit psychometric function to response data using maximum likelihood estimation
- Measure: Hearing threshold at perceptual ‘sweet point’ (72.9% correct responses)
- Draw a graph laying out a psycho-acoustical experiment as (Kingdon and Prins, 2010).
- What is psychoacoustics good for?
Attributes of physical stimuli are mapped onto
perceptual dimensions: Equal-loudness curves
