Exam 3 Flashcards
psychoacoustics
the study of the perception of sound:
- how we listen
- our physiological responses
- physiological impact of music and sound on the human nervous system
relationship between frequency and pitch
frequency = acoustic concept
pitch = physiological concept
-highly correlated with each other
-higher frequency = higher pitch
relationship between intensity and loudness
intensity (physical features of sound; dBSPL)
loudness (physiological response toward sound intensity)
-higher sound intensity = louder sound
3 auditory tasks
- auditory sensitivity (detection)
- auditory discrimination
- auditory identification (recognition)
auditory sensitivity
detection
don’t need to identify the sound, just the stimulus
need to hear sound to perceive it
auditory discrimination
when you have 2+ sounds, you have to decide if they are the same or different
auditory identification
recognition
identify meaning of speech and understand the meaning it carries
ex: speech recognition
most important task
psychoacoustic methods
- method of limit
- method of constant stimuli
- scaling method
method of limit
how we measure the response to sound
- ascending and descending; adaptive
- fixed step size
- threshold: average of reversals
ascending and descending factors in method of limit
- ascending: start at a low level and bump up until a person can hear something (adaptive)
- descending: start on a higher level and go down until the person can’t hear anything
- some bias for descending bc the person has anticipation for the sound bc they have heard it before
- ascending is more conservative bc they can be sure of a heard sound if they start with none-
- do both–>combination of both gives a better threshold
fixed step size factors in method of limit
increasing or decreasing the sound by a fixed number every time
(5 dBSPL) 10–>15–>10–>15–>20
threshold/average of reversals factors in method of limit
- reversal = point at which the direction of sound changes
- point before and after the levels change
- to get threshold, you need to average reversals
- 7 reversals–>throw out first 3 and average remaining 4 to get reliable threshold
- threshold % is based on up, down rules
method of constant stimuli
- a # of stimuli ranging from rarely to almost always perceivable are presented one at a time and the subject responds to each stimuli (yes/no)
- equal number of stimuli at each level
- psychometric function–>plots % correct of auditory perception as a function of sound level
- threshold: a certain % point; lowest sound level we can hear
- measure at each level the % the listener gets correct–>usually creates an “S” shaped curve (curve is called psychometric function)
scaling method
- direct scaling: directly establishes the correspondence between physical sounds and their perception (loudness and pitch)
- ratio scale: compare target sound (given) to reference sound; used to tell how much louder the target is than the reference
- magnitude scale: no reference sound provided; just how you perceive the sound–>1-10 loudness scale; based on personal experiences
audibility
sound that is loud enough to be heard; basic sound detection
