Unit 3 (Psychoacoustics) Flashcards
Psychoacoustics
the study of the relationship between the acoustic world and our auditory (perceptual) image of this world.
It is a branch of Psychophysics, which is the study of the relationship between the physical world and the perceptual world across all of the senses.
The Audiogram
Higher sound levels are at the bottom. The higher the threshold, the more loss the patient has, the lower you are on the graph.
dropping down represents loss
Why is there not a one-to-one ratio of changes in physical and perceptual scales?
perhaps because of combination of a place mechanism at the highest frequencies, a phase-locking mechanism at the lowest frequencies, and both mechanisms in between.
Masking
How sensitivity for one sound is affected by presence of another sound.
complete masking - change in threshold (sound not audible)
Partial Masking - reduction in loudness (we would still hear it)
Masking is primarily the result of interference within the cochlea of traveling waves due to different sounds.
Masking (not always an advantage)
background noise can mask spoken word.
Masking (deliberate)
Audiology clinic
sound comes across. sound in non-test ear will be 40 db lower than the sound in the test ear.
improving acoustical privacy
tinnitis relief (masking can specifically block tinnitis)
Webers Law
Weber’s Law states that the just noticeable difference (JND) in a stimulus is a constant proportion of the original stimulus intensity, meaning that the amount you need to change a stimulus to perceive a difference is always a set percentage of the original stimulus, regardless of its absolute intensity; mathematically represented as: ΔI / I = k where ΔI is the just noticeable difference, I is the original stimulus intensity, and k is a constant value specific to the sense being measured
how well Weber’s law holds for frequency and level (intensity)
Weber’s law always fails at low intensities, near and below the absolute detection threshold, and often also at high intensities, but may be approximately true across a wide middle range of intensities.
Psychophysics
“The study of the relationship between the physical worlds and the perceptual world across all of the senses.”
*the study of the relationship between various physical aspects of the stimulus and the psychological reaction (sensation).
The relationship btwn. stimulus and perception is not a simple one-to-one mapping.
EX: doubling the intensity of a sound does not double the perceived loudness
-to actually double the perceived loudness, one much actually increase the intensity by approx. 10 times
Sensation
awareness of an external stimulus, or of a change in the internal state of the body caused by an external stimulus.
*the response of the biological system to a stimulus which is received by a sense organ.
Perception
The act of recognition and interpretation of as stimulus based on previous experiences
*is the interpretation of the response.
Psychophysical Measurement
Experimental procedures
Test Stimuli
the stimulu used in psychophysical measurements
Judgements
human responses to test stimulu
Listener
a participant who is expecting to hear a stimulus
trained listenere
someone who is able to detect subtle changes in a a sound better than other listeners with the same physiologic capabilities. A result of innate ability, training in a related area, or specific training in the field.
Thresholds
the limits of the system. measurment of the smallest detectable stimulu, or changes.
Scale
measures how sensation changes from just detectable to higher values.
–> Decibel scale is a physical scale
–> Loudness scale is a psychophysical scale
