CH 5 Auditory Perception (QUESTION) Flashcards
What is the range of frequency that humans can hear? What does frequency produce?
- 30-20,000 Hz
- Pitch
What is the range of amplitude that humans can hear? What does amplitude produce?
- 0-160 dB
- Loudness
What does the complexity of a wave produce?
Timbre
Describe the structure of the ear (3,18)
- Outer Ear (Pinna): Pinnea, Auditory canal, Eardrum
- Protection
- Middle Ear: Ossicles
- Amplification
- Inner Ear (Cochlea): Oval window, Cochlea, Basilar membraneβ which contains the Tympanic canal, Cochlear duct, Organ corti and several other structures within it (tectorial membrane, outer hair cells, inner hair cells, spiral ganglion cells and auditory nerve)
- Transduction
What is the Pinna? (3)
- Part of the outer structure of ear
- Channels sound
- Localization
What is the Auditory Canal? (2)
- Part of the outer structure of ear
- Slightly amplifies sounds between 2,000 and 7,000 Hz (resonance frequency)
What is the Eardrum? (2)
- Part of the outer structure of ear
- Vibrates according to frequency of the sound
What are the Ossicles? (3)
- Part of middle ear
- Three smallest bones in body: Hammer, Anvil, Stirrup
- Acts both as a lever and funnels vibrations from the large eardrum to the small oval window (increased pressure by factor of 30)
What is the Oval Window? (2)
- Part of inner ear
- Vibrates to frequency of sound
What is the Cochlea?
- Part of inner ear
- Receptors for hearing
What is the Basilar Membrane? (2)
- Structure of inner ear
- Separates tympanic canal from cochlear duct (two fluid-filled chambers in the inner ear)
Cochlear Duct (2)
- Structure of inner ear
- Contains Organ of Corti
Organ Corti
- Structure of inner ear; Found in Cochlear Duct
- Rests on basilar membrane
The main sensory organ for hearing, containing structures that conduct transduction:
- Tectorial membrane
- Outer hair cells
- Inner hair cells
- Spiral ganglion cells
- Auditory nerve
Describe the process of transduction (4)
- Each hair cell in the ear has many fine filaments or cilia
- Hair cells attached to basilar membrane and cilia are attached to tectorial membrane
- Vibration of basilar membrane produces shearing action and cilia bend
- Bending action allows potassium to flow into cell β¨ release of neurotransmitters to dendrites of spiral ganglion cells
What is the Tectorial membrane?
A structure that interacts with hair cells to detect sound vibrations
What are the Outer and inner hair cells?
Sensory cells that bend in response to vibrations, generating neural signals
What are the Spiral ganglion cells?
Nerve cells that relay sound information to the brain.
What is the Auditory nerve?
Carries signals from nerve cells to the brain, allowing us to perceive sound
Explain how traveling waves move through the cochlea to produce different sounds (11)
Traveling waves move through the cochlea based on sound frequency, supporting place theory of pitch perception
-
High-frequency sounds (top image)
- Produce waves that collapse early, near the base of the cochlea (close to the oval window).
- This region is narrow and stiff, making it more responsive to high-pitched sounds.
-
Medium-frequency sounds (middle image)
- Travel further along the basilar membrane before collapsing.
- Activate a mid-region of the cochlea.
-
Low-frequency sounds (bottom image)
- Travel deeper into the cochlea, collapsing near the apex.
- The apex is wide and flexible, making it more sensitive to lower pitches.
This process allows the brain to determine pitch based on where the vibrations peak along the basilar membrane
Depending on pitch, what mechanism does the ear use to produce sound? (3)
- Below 500 Hz β Only Frequency Coding (entire membrane vibrates, neurons fire at sound frequency).
- 500 β 5,000 Hz β Both Frequency & Place Coding (neuron firing + specific locations on the basilar membrane).
- Above 5,000 Hz β Only Place Coding (frequency detected by location of peak vibration).
