Introduction to hearing Flashcards
How do we hear?
Sound stimulus causes pressure changes in the air which are detected by the ear. This sends signals to the brain
What is sound?
Movements or vibrations of an object cause pressure changes in any elastic medium (e.g., air, water). Alternation if condensation (high air pressure) and rarefaction (low air pressure) of air particles when the membrane moves back in
What is a sound wave?
A variation in air pressure propagating through a medium
What is amplitude?
Difference in pressure between peaks and troughs which determines loudness
What is frequency?
How many times per second the pressure change cycle repeats (Hz) which determines pitch
What is signal transduction?
The sound stimulus arrives at the receptors, where it is transduced to an electrical signal in the inner ear. These signals are processed to indicate pitch and loudness
What is in the middle ear?
Malleus, incus, stapes - ossicles, eardrum
What is the most important structure in the inner ear?
The cochlea
What does the cochlea partition separate?
Scala vestibuli and scala tympani
What does the corti contain?
Hair cells which are the receptors for hearing. Damage to these cells can be a cause of deafness
What is transduction?
Cilia (protrusions from hair cells) bend in response to pressure changes. Vibrations of the liquid travel through the cochlea, causing the basilar membrane to move up and down. When these vibrations become electric signals, it’s called transduction
What is a tonotopic map?
Hair cells sensitivity to pitch depends on their location along a tonotopic map along the cochlea
What is the function of the primary auditory cortex?
Auditory nerves in the cochlea relay in the brain stem, mid-brain and the thalamus. It also has a tonotopic map (neurons responding to low frequencies towards the front of the brain)
Where can sounds be localised to based on binaural cues?
Temporal differences between sounds coming to the left and right ear
Where can sounds be localised to based on monaural cues?
The way sound is reflected by head and pinnae (outer ear) depends on sound location
