08 - Audition - Next sense…Hearing Next Sound Sound...

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Unformatted text preview: Next sense…Hearing Next Sound Sound Movement of air molecules from a source of vibration Frequency- (pitch) the rate at which waves vibrate measured Frequencyas cycles/sec (Hz) as Amplitude (loudness)- the intensity of sound, measured in dB Complexity (timbre)- mixture of frequencies, can be simple Complexity or complex, difference in sound btw a violin and trumpet or Outer Ear- The pinna Outer Sound arrives outer ear Catches sound waves Outer ear funnels in Outer sound to eardrum sound Eardrum Eardrum Vibrates when sound Vibrates waves hit Miniature drum Tympanic Membrane Middle Ear Middle Vibrating eardrum Vibrating causes the 3 ossicles to vibrate vibrate Hammer, anvil, & Hammer, stirrup stirrup Amplify and convey Amplify vibrations to oval window window Ossicles Ossicles In Latin “malleus, incus, and stapes” translated the hammer, the anvil, and the stirrup. The malleus articulates with the incus and is The attached to tympanic membrane attached The incus is connected to both the other bones. The The stapes articulates w/ incus and is attached The to the oval window or opening btw middle ear and the vestibule of the inner ear. Inner Ear Inner Transduces sound Transduces vibrations into electrical signal electrical Transmitted to Transmitted brain brain Cochlea Cochlea Cochlea The auditory hair cells The sit within the organ of Corti. Inner hair cells-the -the auditory receptors in tectorial membrane tectorial Outer hair cells- help help to "tune" the cochlea and provide support Basilar Membrane Basilar Basilar membrane bounces up and down stereocilia are sheared Basilar back and forth under the tectorial membrane. When stereocilia are pulled, the hair cell depolarizes. When This signal is transmitted to the auditory nerve to the brainstem. This Basilar membrane Basilar The basilar membrane is actually thinner and The narrower at the base of the cochlea than at the tip (apex) High frequencies vibrate at the base of the High cochlea and to low frequencies at the apex. It is the properties of the basilar membrane It that set up this gradient, not the properties of the hair cells. the Tonotopic organization Tonotopic Superior Olive Superior The ventral cochlear nucleus cells then project The to a collection of nuclei in the medulla called the superior olive. superior Where differences timing and loudness of the Where sound in each ear are compared Helps determine the direction the sound came Helps from. from. Interaural Time differences Binaural Cues Binaural Interaural Time Difference (ITD)- biological binaural cue is the split-second delay between the time when sound from a single source reaches the near ear and when it reaches the far ear. Interaural Amplitude (intensity) Difference (IAD)(IAD)Sound amplitude and pressure differences Sound between each ear between Auditory (Vestibular) Pathway Auditory Hair cells → spiral ganglion. → cochlear nerve Hair → vestibulocholear nerve → medulla oblongata (superior olive) → inferior colliculus (midbrain) → thalamus → auditory cortex Purpose is to keep tabs on position/motion of head in space. detect rotation, shake or nod your head (angular acceleration). detect motion along a line - elevator drops, lean body (linear linear acceleration) acceleration 3 semicircular canals detect angular acceleration in 3 mvnt semicircular dimensions, each canal detects motion in a single plane dimensions, ...
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