Hearing Chapter 6, Lecture 3 “From vibrating air to moving piston to fluid waves to electrical impulses to the brain: Voila! We hear.” - David Myers
Hearing The Stimulus Input: Sound Waves Sound waves are compressing and expanding air molecules. Preview Question 8: What are the characteristics of air pressure waves that we hear as sound?
Sound Characteristics Frequency (pitch) Intensity (loudness)
The Ear Dr. Fred Hossler/ Visuals Unlimited Preview Question 9: How does the ear transform sound energy into neural messages?
The Ear Outer Ear: Collects and sends sounds to the eardrum (the pinna). Middle Ear: Chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window. Inner Ear: Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
Cochlea Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.
Intensity (Loudness) Intensity (Loudness): Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness.
Loudness of Sound Richard Kaylin/ Stone/ Getty Images 120dB 70dB
Frequency (Pitch) Frequency (pitch): The dimension of frequency determined by the wavelength of sound. Wavelength: The distance from the peak of one wave to the peak of the next. Preview Question 10: What theories help us understand pitch perception?
Perceiving Pitch Place Theory: the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated (good for determining high pitches). Frequency Theory: the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone (good for determining low pitches). Preview Question 10: What theories help us understand pitch perception?
Localization of Sounds Because we have two ears, sounds that reach one ear faster and with greater intensity than the other ear cause us to localize the sound. Preview Question 11: How do we locate sounds?
Can we practice this in class? Localization of Sound 1. Intensity differences 2. Time differences Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound barrier. Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants? Can we practice this in class?
Hearing Loss How might someone develop each of these? Conduction Hearing Loss: caused by damage to the mechanical system that conducts sound waves to the cochlea Sensorineural Hearing Loss: caused by damage to the cochlea’s receptor cells or to the auditory nerves; also called nerve deafness. Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants? How might someone develop each of these? Let’s read more about hearing loss…
From A Quiet World by David Myers Myers passes along these specific tips for friends, colleagues, and family members of the hearing impaired: Invite us to a quiet place, for example, a room without loud music, a carpeted restaurant, a chair away from the air conditioning. Capture our attention. If we are reading or watching television, make certain we’re looking at you. Face the light and face us. Since we all do some lipreading, it helps to see your mouth. And don’t conclude that we are rude if we look at your mouth rather than your eyes. Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants? Speak slowly. Don’t holler, but enunciate each word with pauses between phrases and sentences.
From A Quiet World by David Myers Myers passes along these specific tips for friends, colleagues, and family members of the hearing impaired: Rephrase. If we don’t seem to hear it, restate it. Try using different words to express the same thought. Change “Do you want something from the store?” to “Can I get you something at Safeway?” Create a context. Help us to know the subject. Have a printed agenda for meetings, use visual aids. Caller I.D. is a blessing for us. Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants? Ask us if we have heard. Remember, we don’t like to seem inept or to embarrass both of us by volunteering what we did not hear.
Homework Read p.252-263 “People who lose one channel of sensation do seem to compensate with a slight enhancement of their other sensory abilities.” - David Myers Preview Question 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants?