Auditory System
AUDITORY SYSTEM NOTES
Questions 1. What is sound? 1. What are the physical dimensions of sound 2. What are the perceptual dimensions of sound 3. What sounds can humans hear? 2. What is the anatomy of the ear? 3. What are the brain structures and pathways involved in the perception of hearing? 4. How do we localize sounds?
Why do we hear?
* Communication iHelen Keller felt that being deaf was worse than being blind, because blindness isolated her from things, but deafness isolated her from people * Enables you to perceive dangers outside of the visual receptive field
What is sound? (difference between physical and percept definitions can be illustrated by tree falling in forest explanation) * Physical definition; Repetitive change in air pressure over time.
* Perceptual definition;
The experience we have when we hear
Sound as Pressure Changes
Sound occurs when movement/vibration of an object causes pressure changes in the elastic medium i.e. air
Waves enter ear and are transduced into sound the waves travel but not the molecules
Sound WAVE: pattern of compression and rarefaction of air molecules due to the movement of the ‘sound emitting’ object
(travels through air at 340m/s and through water at 1,500 m/s)
Different kinds of sounds depending on the waves * Pure Tones; simple waves i.e high pitch notes produced by flute * Harmonics; complex waves…combinations of PureTones
PURE TONES
Occurs when pressure changes in the air occur in a pattern described by a mathematical function called a sine wave * Tones with this pattern of pressure changes are only occasionally found in the environment (i.e. person whistling/high pitched notes from flute are close to pure tones)
Also tuning forks, designed to vibrate with a sine-wave motion produce pure tone * For lab studies of hearing, computers generate pure tones that cause a speaker diaphragm to vibrate in and out
Questions 1. What is sound? 1. What are the physical dimensions of sound 2. What are the perceptual dimensions of sound 3. What sounds can humans hear? 2. What is the anatomy of the ear? 3. What are the brain structures and pathways involved in the perception of hearing? 4. How do we localize sounds?
Why do we hear?
* Communication iHelen Keller felt that being deaf was worse than being blind, because blindness isolated her from things, but deafness isolated her from people * Enables you to perceive dangers outside of the visual receptive field
What is sound? (difference between physical and percept definitions can be illustrated by tree falling in forest explanation) * Physical definition; Repetitive change in air pressure over time.
* Perceptual definition;
The experience we have when we hear
Sound as Pressure Changes
Sound occurs when movement/vibration of an object causes pressure changes in the elastic medium i.e. air
Waves enter ear and are transduced into sound the waves travel but not the molecules
Sound WAVE: pattern of compression and rarefaction of air molecules due to the movement of the ‘sound emitting’ object
(travels through air at 340m/s and through water at 1,500 m/s)
Different kinds of sounds depending on the waves * Pure Tones; simple waves i.e high pitch notes produced by flute * Harmonics; complex waves…combinations of PureTones
PURE TONES
Occurs when pressure changes in the air occur in a pattern described by a mathematical function called a sine wave * Tones with this pattern of pressure changes are only occasionally found in the environment (i.e. person whistling/high pitched notes from flute are close to pure tones)
Also tuning forks, designed to vibrate with a sine-wave motion produce pure tone * For lab studies of hearing, computers generate pure tones that cause a speaker diaphragm to vibrate in and out