Chapter 6 - Quiz 3 Flashcards
6.1 Sound and the Ear: Physics and Psychology of sound
What are sound waves?
-periodic compressions of air, water or other media
-vary in amplitude and frequency
6.1 Sound and the Ear: Physics and Psychology of sound
Define amplitude
-the intensity of a sound wave or height of the wave
–in general, sounds of greater amplitude seem louder, but exceptions occur
6.1 Sound and the Ear: Physics and Psychology of sound
Define frequency and what its measured in? (2)
-number of compressions per second
-measured in hertz
-sounds higher in frequency are higher in pitch
-a graph of lower frequency would be less waves per distance, so think of less choppy water
6.1 Sound and the Ear: Physics and Psychology of sound
Define pitch
-related aspect of perception
6.1 Sound and the Ear: Physics and Psychology of sound
Define timbre
-tone quality or complexity
-how someone can tell the difference between a piano and violin playing the same note at the same volume
6.1 Sound and the Ear: Physics and Psychology of sound
Define prosody
-when someone conveys emotional information by tone of voice
6.1 Sound and the Ear: Structures of the Ear
What are the three main parts of the ear anatomically distinguished by anatomists?
-Outer ear, middle ear, and inner ear.
6.1 Sound and the Ear: Structures of the Ear
What is a part of the outer ear?
-pinna and auditory canal
6.1 Sound and the Ear: Structures of the Ear
What is part of the middle ear?
-tympanic membrane and ossicles (hammer, anvil, stirrup)
6.1 Sound and the Ear: Structures of the Ear
What structures are part of the inner ear?
-cochlea, oval window, hair cells, auditory nerve
6.1 Sound and the Ear: Structures of the Ear
What is the function of the pinna in the outer ear?
-helps locate the source of a sound by altering the reflections of sound waves.
-Each person’s pinna is uniquely shaped, requiring individual learning to use this information effectively
-Rabbits have large, movable pinnas for more precise sound localization.
6.1 Sound and the Ear: Structures of the Ear
What role does the tympanic membrane play in the middle ear?
-aka eardrum
-vibrates in response to sound waves and transmits these vibrations to the three tiny bones in the middle ear.
6.1 Sound and the Ear: Structures of the Ear
What are the three tiny bones in the middle ear called? In English and Latin? (2)
-hammer, anvil, and stirrup
-malleus, incus, and stapes
6.1 Sound and the Ear: Structures of the Ear
How do the three tiny bones in the middle ear amplify sound?
-They transmit vibrations from the tympanic membrane to the oval window with increased force, converting sound waves into waves of greater pressure.
-The tympanic membrane is about 20 times larger than the footplate of the stirrup, amplifying the vibrations like a hydraulic pump.
6.1 Sound and the Ear: Structures of the Ear
What happens when the stirrup vibrates the oval window in the inner ear?
-It sets the fluid in the cochlea into motion, which displaces the hair cells and opens ion channels in their membranes.
6.1 Sound and the Ear: Structures of the Ear
What do the hair cells stimulate and where are they located between? (2)
-stimulate the auditory nerve (part of the eighth cranial nerve)
-located between the basilar and tectorial membranes of the cochlea
6.1 Pitch Perception
What is place theory in hearing and how does it explain our perception of different pitches? What is an example? (3)
-Theory: Different parts of the cochlea are activated by different sound frequencies.
-How: Pitch is determined by where hair cells are stimulated along the cochlea.
-Example: In the scenario of a party with a DJ booth where high-energy music with thumping bass is played, the sensation of feeling the bass more intensely near the DJ booth corresponds to the place theory, where the location of stronger vibrations along the basilar membrane indicates higher pitch perception in our brain.
-High-frequency sounds activate the base; low-frequency sounds activate the apex.
-This mapping helps us distinguish different pitches.
-each frequency activates the hair cells at only one place along the basilar membrane, and the nervous system distinguishes among frequencies based on which neurons respond.
6.1 Pitch Perception
What is the downfall of place theory?
-various parts of the basilar membrane are bound too tightly for any part to resonate like a piano string
-Essentially, the downfall indicates a discrepancy between the proposed mechanism of the theory and the physical structure of the basilar membrane.
6.1 Pitch Perception
What is frequency theory in hearing? What is an example? (2)
-Theory: entire basilar membrane vibrates in synchrony with a sound, causing auditory nerve axons to produce action potentials at the same frequency
-Example: In the context of people clapping at a party to music, where each clap represents a sound wave, the frequency theory suggests that the pitch we perceive is determined by the speed of the claps; thus, in slower music, like a gentle song, where claps occur at a slow, steady pace, our brain interprets the low pitch due to this steady rhythm.
-for example, a sound at 50 Hz would cause 50 action potentials per second in the auditory nerve
6.1 Pitch Perception
What is the downfall of frequency theory?
-the refractory period of a neuron is typically much lower than the highest Hz of frequencies we hear
-its usually around 1000 Hz, but we can hear much higher frequencies
6.1 Pitch Perception
What is the current theory for how we hear things? Explain it for low, higher, and extremely high frequencies? (3)
-The current theory combines elements of the frequency theory and the volley principle.
For low-frequency sounds (up to about 100 Hz):
-frequency theory
At higher frequencies:
-Volley principle explains pitch discrimination up to 4000 Hz.
Beyond 4000 Hz:
-Mechanism similar to place theory used.
-Point of peak vibration on basilar membrane identifies sound frequency.
-soft sounds activate fewer neurons and stronger sounds activate more
-Low frequencies are like synchronized claps representing slower music.
-High frequencies are like claps following the rhythm, even if not perfectly in sync.
-Beyond 4000 Hz, it’s like figuring out the music genre by where the loudest claps are coming from.
6.1 Pitch Perception
What is the volley principle? Use an example to explain. (2)
-theory: auditory nerve produces volleys of impulse for sounds up to about 4000 per second
-Example: Imagine a relay race where runners pass a baton to keep up speed. Similarly, groups of neurons take turns firing to keep pace with high-frequency sounds. While no single neuron fires at the sound’s frequency, together they create a volley of impulses to match it.
-The volley principle explains how groups of neurons work together to perceive pitch.
-volleys of impulses for sounds up to about 4000 per second, even though no individual axon approaches that frequency
6.1 Pitch Perception Stop and Check 191
Through which mechanism do we perceive low-frequency sounds (up to about 100 Hz)?
-At low frequencies, the basilar membrane vibrates in synchrony with the sound waves, and each responding axon in the auditory nerve sends one action potential per sound wave.
-frequency theory
6.1 Pitch Perception Stop and Check Pg 191
How do we perceive middle-frequency sounds? (100-4000 Hz)?
-At intermediate frequencies, no single axon fires an action potential for each sound wave, but different axons fire for different waves, and so a volley (group) of axons fires for each wave.
-volley principle