Chapter 9: Hearing, Vestibular, Taste and Smell Flashcards
Sound
Oscillation of increases and decreases in air pressure.
How is sound typically discussed?
As waves
Amplitude
Distance between the resting position and maximum height of the wave.
What is amplitude measured in?
Decibles (dB)
Frequency
The number of waves passing by a specific point per second.
What is frequency measured in?
Hertz (Hz)
Pure Tone
A single frequency
Most sounds are not…
pure tones
Fourier Analysis
Decomposes sound into its separate sine waves.
What type of force is sound?
Mechanical
What is used to detect sound?
Mechanoreceptors
Middle Ear
Controlled by stapedius and tensor tympani muscles.
How does the middle ear reduce effectiveness of sound?
Stiffening links of bone.
What is the middle ear important for?
Decreasing self-made sounds
Inner Hair Cell
Transduces the physical force into the neural signal.
Basilar Membrane
Has different sensitivities to different frequencies.
What does the stiff base of the basilar membrane respond better to?
High frequencies
What does the floppy apex of the basilar membrane respond better to?
Low frequencies
Inner Hair Cells (IHCs)
Responsible for perception of sound.
What % of the auditory fibers are from IHCs?
90-95%
Outer Hair Cells (OHC)
Help to fine-tune organ of Corti in response to messages from the brain.
Cochlear Amplifier
Amplify movements of basilar membrane in some areas while dampening in others.
Neurons Tuning Curve
Auditory neurons have a precise frequency they are most sensitive to, but also respond to nearby frequencies.
Where do binaural interactions occur?
The brainstem and superiors olivary nucleus
Tonotopic Organization
Organization of the auditory system.
What do the auditory systems try to analyze?
- Pitch
- Source of the sound
Place Theory
Encoded by area of basilar membrane with maximal excitation.
Volley Theory
Frequency encoded by firing frequency.
What type of frequency is the volley theory mainly used for?
Lower frequencies
Binaural Neurons
Serve as “coincidence detectors”
Lateral Superior Olive
Processes latency differences in mammals.
Medial Superior Olive
Processes latency differences but compares ENTIRE activity of MSO on left vs right.
External Ear
Provides spectral filtering and amplifies certain frequencies.
What are the 3 ossicles in the ear?
- Malleus
- Incus
- Stapes
Auditory Cortex
Processes Complex Sounds
The auditory cortex is not involved in…
basic auditory discrimination (can be accomplished at lower levels)
Dorsal Stream
Focuses on localization
Ventral Stream
Analyzes components of sound.
What causes cells to shift their tuning curve?
Experience