Chapter 9
- Function of Hearing
- What is Sound?
- Frequency (Pitch) and Amplitude (Loudness)
- Complex Tones and Fourier Analysis
- Fundamental Frequency
- Harmonics
- Timbre
- Basic Structure
- Outer Ear
- Tympanic Membrane (eardrum)
- Middle Ear
- Middle ear bones (ossicles)
- Oval window
- Muscles of the middle ear
- Inner Ear
- Cochlea
- Basilar Membrane
- Inner hair cells
- Outer hair cells
- Tectorial Membrane
- Round window
- Inner Hair Cells
- Stereocilia (the ‘hairs’ on hair cells, stereocilia are like the ‘dendrites’ on a regular neuron)
- Place code – an inner hair cell’s position in the basilar membrane determines it’s frequency tuning. High frequency tuning towards the base (narrow end) and low frequency tuning towards the apex (wide end).
- Outer Hair Cells
- Amplification and Tuning
- Auditory Brain Structures
- Hindbrain
- Cochlear nuclei
- Midbrain
- Inferior colliculus (‘where’ pathway
- Thalamus
- Medial geniculate nucleus (‘what’ pathway)
- Cortex
- Temporal lobe
- Primary auditory cortex
- Frequency-specific responses (just like cochlea)
- Belt, Parabelt (i.e., secondary and tertiary areas)
- Responses become more complex
- Basic Operating Characteristics
- Intensity and Loudness
- Threshold varies with frequency
- Frequency and Pitch
- Best resolution below 5000 Hz
- Place Coding
- Hearing Loss
- Conductive
- Problem with middle ear
- Helped by hearing aid
- Sensorineural
- Problem with inner ear
- Helped by cochlear implant
Chapter 10
- Sound Localization (Where)
- Interaural time difference
- Interaural level (intensity) difference
- Complex Sounds (What)
- Harmonics
- Timbre
- Auditory Scene Analysis
- Grouping by timbre (i.e., grouping by ‘what’)
- Grouping by onset (i.e., grouping by ‘where’)
- Continuity and Restoration Effects
- The whole is greater than the sum of the parts
Chapter 11
- Music
- Music allows sound to stimulate emotional regions in the brain
- Sound processing becomes like taste or smell processing
- Octaves: pitch ascends like a ‘coil’ even though frequency ascends in a linear fashion.
- Chords: lateral relationships within the ‘coil’ – much of the emotional content of music comes from chords
- Cultural differences: emotional relationships to sounds are learned
- Making Music
- Melody
- Rhythm
- Harmony
- Speech
- Speech Production
- Phonation (air, trachea, larynx)
- Fundamental frequency of speech
- Produces harmonic frequencies in lower half of face
- Articulation (lower half of the face)
- Modulating harmonic frequencies in the lower half of the face
- Formant frequencies
- Speech Perception
- The Problem of Coarticulation
- Importance of preceding and following sounds
- Categorical Perception
- Tuning for speech sounds
- How is speech ‘speech’
- Importance of visual cues (McGurk Effect)
- Speech learning (development)
- We’re born as ‘universal citizens of earth’
- Experiences tunes mechanisms of speech perception
- More sensitivity to ‘native’ speech sounds
- Lost sensitivity to sounds in other languages
- Same for mechanisms of speech production