01:830:101 Lecture Notes - Lecture 16: Social Influence, Social Exclusion, Sensory Neuron
6 Jun 2018
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Module 20: The Nonvisual Senses
The Nonvisual Senses: Hearing
• Sound waves: From the environment into the brain
• Sound waves compress and expand air molecules
• Ears detect these brief pressure changes
Hearing: Sound Characteristics
• Amplitude (height) determines intensity (loudness) in sound waves
• Length (frequency) determines the pitch
• Sound is measured in decibels (dB)
• 0 dB is the absolute threshold (not the absence of sound, just less than we can hear)
• 60 dB is normal conversation
• 85+ dB: prolonged exposure can cause hearing loss
• Sound waves are bands of compressed and expanded air.
• Human ears detect these changes in air pressure and transform them into neural impulses,
which the brain decodes as sound.
• Sound waves vary in amplitude, which is perceived as differing loudness, and in frequency,
which is experienced as differing pitch.
Sound Waves
• Hearing is about sound waves and changes in air pressure that unfolds over time.
▪ Sound waves—Changes in air pressure unfolding over time
▪ Oscilloscope—An electronic laboratory instrument that traces a visible wave form
▪ Amplitude—The intensity or amount of energy of a wave, reflected in the height of the
wave; it determines volume
▪ Frequency—The rate of vibration, or the number of sound waves per second; it
determines pitch (highness or lowness of sound)
▪ Decibels (dB)—Measurement unit for sound
▪ Hertz (Hz)—Measurement unit
Perceiving Loudness, Pitch, and Location
• Place theory in hearing--Hemholtz
• Theory that liks the pith heard ith the plae here the ohlea’s erae is
stimulated; best explains high pitches
• Frequency theory (temporal theory) in hearing
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2
• Theory that the rate of nerve impulses traveling up the auditory nerve matches the
frequency of a tone, thus enabling its pitch to be sensed; explains low pitches
• Some combination of place and frequency theories
• Handle the pitches in the intermediate range
Localizing Sound Sources
• Ears on either side of the head gives us stereophonic hearing.
• Timing method—noting direction of sound by which ear is stimulated first (best with low
frequency sounds)
• Volume method—noting direction of sound by which ear is stimulated most vigorously (best
with high frequency sounds)
How Do We Locate Sounds?
WHY TWO EARS ARE BETTER THAN ONE
• Sound waves strike one ear sooner and more intensely than the other
• From this information, our brain can compute the sound's location
Hearing Loss
• Sensorineural hearing loss (nerve deafness)
• Damage to cell receptors or associated nerves
• Conduction hearing loss
• Damage to mechanical system that conducts sound waves to cochlea
• Cochlear implant: a device for converting sounds into electrical signals and stimulating the
auditory nerve through electrodes threaded into the cochlea
The Nonvisual Senses: Touch
• Sense of touch is actually a mix of four distinct skin senses
• Pressure
• Warmth
• Cold
• Pain
• Other skin sensations are variations of the basic four
The Pain Circuit
Sensory receptors (nociceptors) respond to potentially damaging stimuli by sending an impulse to the
spinal cord, which passes the message to the brain, which interprets the signal as pain.
Gate control theory
• The spinal cord contains small nerve fibers that conduct most pain signals, and larger fibers that
conduct most other sensory signals.
• Melzak ad Wall theorized that the spial ord otais a eurologial gate
• When tissue is injured, the small fibers activate and open the gate, and you feel pain.
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01:830:101 Full Course Notes
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Document Summary
The nonvisual senses: hearing: sound waves: from the environment into the brain, sound waves compress and expand air molecules, ears detect these brief pressure changes. Perceiving loudness, pitch, and location: place theory in hearing--hemholtz, theory that li(cid:374)ks the pit(cid:272)h heard (cid:449)ith the pla(cid:272)e (cid:449)here the (cid:272)o(cid:272)hlea"s (cid:373)e(cid:373)(cid:271)ra(cid:374)e is stimulated; best explains high pitches, frequency theory (temporal theory) in hearing. Why two ears are better than one: sound waves strike one ear sooner and more intensely than the other, from this information, our brain can compute the sound"s location. The nonvisual senses: touch: sense of touch is actually a mix of four distinct skin senses, pressure, warmth, cold, pain, other skin sensations are variations of the basic four. Sensory receptors (nociceptors) respond to potentially damaging stimuli by sending an impulse to the spinal cord, which passes the message to the brain, which interprets the signal as pain. Controlling pain: placebo, distraction, social influence theory. The nonvisual senses: taste: like touch, taste.
