PSYC 101 Lecture Notes - Strabismus, Jigsaw Puzzle, Stereoblindness
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Hearing: Sound waves
Audition is the sense of hearing. Auditory perception depends upon sound waves interacting
with structures of the ear. Sound waves are changes over time in the pressure of an elastic
medium (for example, air or water). Without air (or another elastic medium) there can be no
sound waves, thus no sound.
If a tree falls in the forest and no one is around to hear it…it creates sound waves. Waves
received by ears, transduced into neural signals. Without ears to hear it, the waves are just
waves, not sound.
Changes in air pressure are the sound signals. Distance between 2 peaks is the wavelength.
Number of peaks reaching the ear per second is the frequency. Difference between peak
pressure and minimum pressure is the amplitude.
Frequency relates to the pitch we perceive. Amplitude relates to the loudness we perceive -
Expressed in deciBels (dB).
20,000 Hz = highest frequency humans can hear
100-4000 Hz = average useful range of the human voice
27 Hz = Lowest note on a piano
Dimensions of Sound:
Pitch: how high a note appears, associated with frequency. Like hue
Loudness: Associated with amplitude. Like Brightness.
Timbre: Associated with purity or complexity, gives sounds identity. Like saturation.
Pinna – collect and direct sound into auditory canal
Auditory canal – amplify and funnel sound to tympanic membrane
Tympanic membrane (ear drum) - ________________
Malleus (hammer) – vibrates and move the Incus
Incus (anvil) – vibrates and move the stapes
Stapes (stirrup) – vibrate against oval window or cochlea.
Cochlea – filled with fluid and contains receptors for hearing (Hair cells)