Final Review Flashcards
Sound wave
Undulating displacement of molecules caused by changing pressure
Frequency
Number of cycles that a wave completes in a given amount of time
Measured in hertz (Hz), or cycles per second
Corresponds to our perception of pitch
Low pitch, low frequency (fewer cycles/second)
High pitch, high frequency (many cycles/second)
Differences in frequency are heard as differences in pitch
Amplitude
The intensity, or loudness, of a sound, usually measured in decibels (dB)
The magnitude of change in air molecule density
Corresponds to our perception of loudness
Soft sound, low amplitude
Loud sound, high amplitude
Complexity
Pure tones - Sounds with a single frequency
Complex tones - Sounds with a mixture of frequencies
Fundamental frequency - The rate at which the complex waveform pattern repeats
Overtones - Set of higher frequency sound waves that vibrate at whole number (integer) multiples of the fundamental frequency
Hearing for Humans
- 20 to 20,000 Hz (young adults)
- Prolonged exposure to sounds louder than 100 decibels is likely to damage human hearing
Auditory System
Ear collects sound waves from surrounding air
Converts mechanical energy to electrochemical neural energy
Routed through the brainstem to the auditory cortex
Outer Ear
Pinna
External ear canal
Tympanic membrane
Pinna
Funnel-like external structure designed to catch sound waves in the surrounding environment and deflect them into the ear canal
External ear canal
Amplifies sound waves somewhat and directs them to the eardrum
Tympanic membrane
Aka ear drum
Vibrates based on frequency of sound waves
Connects to middle ear
Middle Ear
Air-filled chamber that comprises the ossicles
Ossicles - Bones in the middle ear - Hammer (Malleus), Anvil (Incus), Stirrup (Stapes)
Connects the eardrum to the oval window of the cochlea, located in the inner ear
Inner Ear
Cochlea Organ of Corti Basilar membrane Hair cells Tectorial membrane
Cochlea
Fluid-filled inner ear structure that contains the auditory receptor cells
Organ of Corti
Receptor cells and the cells that support them
Basilar membrane
Receptor surface in the cochlea that transduces sound waves to neural activity
Hair cells
Sensory neurons in the cochlea tipped by cilia
When stimulated by waves in the cochlear fluid, outer hair cells generate graded potentials in inner hair cells, which act as the auditory receptor cells
Tectorial membrane
Membrane overlying hair cells
Auditory Receptors
Transduction of sound waves to neural activity takes place in the hair cells
(3500 inner hair cells (auditory receptors)
12,000 outer hair cells (alter stiffness of tectorial membrane))
Broca’s area
Anterior speech area in the left hemisphere that functions with the motor cortex to produce the movements needed for speaking
Wernicke’s area
Posterior speech area at the rear of the left temporal lobe that regulates language comprehension
Also called the posterior speech zone
Aphasia
Inability to speak or comprehend language despite having normal comprehension or intact vocal mechanisms
Mapping by brain stimulation
- Auditory cortex: patients often reported hearing various sounds (e.g., ringing that sounded like a doorbell, a buzzing noise, birds chirping)
- A1: produced simple tones (e.g., ringing sounds)
- Wernicke’s area: apt to cause some interpretation of a sound (e.g., buzzing sound to a familiar source such as a cricket)
Disrupting speech
Supplementary speech area on the dorsal surface of the frontal lobes stopped ongoing speech completely (speech arrest)
Eliciting speech
Stimulation of the facial areas in the motor cortex and the somatosensory cortex produces some vocalization related to movements of the mouth and tongue