sound - perception Flashcards
(21 cards)
what are Aristotles 5 senses
taste, smell, touch, see, hear
what are the four additional senses?
balance, pain, body motion, body position
what are the four main sensory receptors and what do each of them do?
Mechano: mechanical forces, pressure
Chemo: chemicals (e.g. in the air, taste)
Noci: pain or tissue damage
Photo: electromagnetic radiation (light)
How does the brain decide what sensory information to focus on?
It takes what’s relevant (selective attention)
What determines how much somatosensory cortex is allocated to a body part?
The amount of use — more use = more cortex (e.g. hands vs knees)
What does cortical representation reflect?
Function and evolutionary importance of the body part
What is the difference between a stimulus, neural response, and perceptual response?
Stimulus: external event
Neural Response: brain’s physiological activity
Perceptual Response: your experience of the stimulus
What does Weber’s Law state?
The Just Noticeable Difference (JND) is a constant fraction of the original stimulus (e.g. 1/20 for weight)
What does Fechner’s Law state?
Perception increases in equal steps based on sensory increments, not stimulus increments
Why should we avoid yes/no questions in perception experiments?
They may introduce bias; better to use forced-choice questions (e.g. “Is it orange or white?”)
What is adaptation in sensory perception? (Fechner)
Sensory sensitivity can change based on context (e.g. being in a dark room)
What is visual prosopagnosia?
A condition where damage to the visual cortex impairs facial recognition
How can neural responses be measured? (invasive and non-invasive techniques)
Invasively: by recording single-cell activity (often in monkeys)
Non-invasively: using EEG or fMRI
What are sine waves made up of?
Amplitude and frequency (time). Higher amplitude = louder, higher frequency = higher pitch. used as complex sounds are made up of multiple sine waves.
What is the cochlea?
A fluid-filled structure in the inner ear where vibrations are converted to neural signals
What is the function of the Organ of Corti?
Converts vibration into neural signals via movement of inner hair cells to stimulate cochlea nerve fibre
What are “hair cells” in the inner ear?
Sensory receptors that respond to different sound frequencies, certain hairs respond to different frequencies
What is phase locking?
Hair cells firing in sync with the phase of the sine wave of a sound
What is Interaural Time Difference (ITD)?
The brain’s ability to locate sound direction based on the time difference it reaches each ear (up to 700 microseconds)
How does the brain use ITDs to locate sound?
Through convergence of signals and phase locking, triggering neural action potentials
how sound is detected by the brain, long answer
Outer Ear: The pinna collects sound waves and funnels them into the auditory canal.
Middle Ear: Sound waves vibrate the tympanic membrane; these vibrations are amplified by the ossicles (malleus, incus, stapes).
Inner Ear: Vibrations enter the cochlea, where fluid movement displaces hair cells in the Organ of Corti.
Transduction & Neural Encoding: Hair cells convert mechanical energy into neural signals; phase locking aids in encoding frequency and timing information.
Localization: Interaural time differences (ITDs) allow the brain to determine the direction of the sound source.
