Cognition: Auditory

Sound

A vibration that travels as a pressure wave

These pressure waves can bunch together or spread out, which causes areas of high pressure and low pressure

Vibration

A periodic motion around a stable point

Rarefaction

Molecules are more spread out

Decreases air pressure

Compression

Molecules are closer together

Increases air pressure

Pinna

External Part of the ear

Ear Canal

Amplifies sound

Some sound is amplified more than others because some sounds are deemed as more relevant to human life

Eardrum/Tympanic Membrane

Vibrates in response to sound waves

Moves the hammer bone, which strikes the anvil, which transfers motion to the stapes

This motion pushes the fluid within the long chambers of the cochlea

Cochlea

Sound vibrations become fluid vibrations which travel as a wave through the cochlea

Basilar Membrane

Vibrates along with the cochlear fluids

Thickness varies so that some parts are easier or harder to make vibrate

Different frequencies make different parts vibrate

Hair cells/Follicles

Transduce mechanical signals into electrical signals

Efferent

Something from the brain cells comes to the hair cells to modulate early auditory perception

Auditory Nerve

Projects to primary auditory cortex

Right ear is processed in the left cortex and vice versa

Dorsal Pathway (auditory)

Sound localization

Where are things

Ventral Pathway (auditory)

Sound properties

What is the sound?

Frequency

A physical property of sound

The number of waves per unit of time

Pitch

A perceptual property of sound

Higher pitches are perceived as louder noises, even if the are played at the same volume

Amplitude

Physical property of sound

Height of the wave

Depends on area of vibration, distance from sound, and the medium/speed of pressure waves

Loudness

Perceptual property of sound

Pitch and Frequency interact to shape perception of loudness

Auditory Scene Analysis

Mental Representation of a sound

Transforms sound waves into meaningful auditory units

Similarity (Gestalt Principle) (Auditory)

Grouping similar pitch ranges together

Proximity (Gestalt Groupings) (Auditory)

Temporal proximity

Sequential integration

Connectedness (Gestalt Grouping) (Auditory)

Sounds that are connected to each other are grouped together