the hearing brain

sound

vibration of an object that leads to molecules in the air being squeezed together and stretching apart

sound is sensitive to

spatial information and temporal information

pure tones

a simple sinusoid wave

pitch

the frequency of the tone

loudness

intensity or amplitude

fundamental frequency

in a complex sounds, the lowest frequency

timbre (tone)

perceived sound quality of a musical note, allows distinction between instruments

outer ear

pinnae, ear lobes, and auditory canals

middle ear

malleus (hammer), incus (anvil), and stapes (stirrup)

middle ear

oval window, cochlea, and basilar membrane

middle ear bones

converts air based sounds into a fluid based code at the oval window

cochlea

concerts the liquid movement into auditory codes via movement into auditory codes viw movement of hair cells house within the basilar membrane of the cochlea

audition pathway

auditory nerve, cochlear nuclei in the MGN, primary auditory cortex A1

A1

located in Heschl’s gyrus within each temporal lobe

belt and parabelt regions

input from both A1 and the medial geniculate nucleus

secondary auditory cortices

process more complex aspects of sounds such as identification and location abilities

dorsal pathway

codes for where in space the sound is coming from and how sound is produced/recreated

ventral pathway

codes for what is it that is making a sound

inter-aural differences

time differences for when the sound arrives at the two ears

planum temporale

part of the auditory cortex integrates auditory and non auditory information

head related transfer function

codes for the density of your head being in the way

ERP

used in EEG by giving participants many trials of a stimuli and measuring the response

mismatched negativity (MMN)

indication from our brain that we are hearing two different sounds

right intraparietal sulcus

shows selective activation when multiple streams need segregation

stream segregation

occurs within the A1 and parietal regions involved in the WHERE pathway

pure word deafness

auditory agnosia seen with LH damage (can identify sounds not speech)

spectrogram

the plot of sound, frequency on Y and time on X, intensity of sound displayed with darker ink

phonemes

basic segments of speech

international phonetic alphabet (IPA)

written symbols for the 100 possible phonemes

formants

free flow of air produced during vowel production

influences of formants

placement of tongue and area of constriction

voicing

vibration of the vocal cords for consonants

coarticulation

the adjacent phonemes influence the production of phonemes

mcgurk illusion

example of a mismatch in heard speech and seen mouth movements