4.4 Audition: More Than Meets the Ear Flashcards
How does the sense of hearing work?
Sound waves; detecting changes in air pressure unfolding over time
What are the three physical dimensions of a sound wave?
Amplitude
Frequency
Complexity
How does Frequency change sound?
Frequency affects the PITCH heard.
Difference in frequency is characterized as a change in Wavelength
How does Amplitude change sound?
Amplitude affects the LOUDNESS of the sound.
Difference in wave height is defined as a change in Amplitude
How does Complexity change sound?
Complexity changes the TIMBRE of the sound. This can be described as the quality or clarity of the sound heard.
Complexity is the mix of sound frequencies
How does our anatomy contribute to localizing sound sources?
We have two ears on opposite sides of our heads. Our heads block the sound from entering each ear equally.
Our ears also receive sounds at slightly different times, since they’re in different locations.
What are the three distinct parts of the human ear?
Outer ear
Middle ear
Inner ear
What is the primary/basic function of each of the three parts of the ear?
Outer - Collect and funnel sounds into the Middle ear
Middle - Transmits vibrations to the Inner Ear
Inner - Transduces vibrations into neural impulses
What’s the outermost part of the ear called?
Pinna
What parts of the ear are included in the Outer ear?
Pinna—> Auditory Canal
What parts of the ear are included in the Middle ear?
Eardrum—> Ossicles—->
What parts of the ear are included in the Inner ear?
Cochlea—-> Semicircular canals
Describe the composition of the Cochlea;
A fluid-filled tube that is the organ of auditory transduction
Houses the BASILAR MEMBRANE + HAIR CELLS
What does the Cochlear Membrane do?
A structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid
What are Hair Cells?
Specialized auditory receptor neurons embedded in the basilar membrane
Theyrelease neurotransmitter molecules, initiating a neural signal in the auditory nerve that travels to the brain
Where do action potentials in the auditory nerve travel to?
The Thalamus and ultimately to an area of the Cerebral Cortex called the primary auditory cortex (also called area A1) in the Temporal Lobe
What do the auditory regions of the left and right hemispheres do?
the auditory region of the LEFT hemisphere analyzes sounds related to LANGUAGE
the RIGHT hemisphere specializes in RHYTHMIC sounds and music
What are the two distinct streams of the auditory regions?
Spatial (where); allow you to locate the source of a sound in space, are handled by areas towards the back
Non-Spatial (what); allow you to identify the sound, are handled by areas in the lower (ventral) part of the auditory region
What is Place Code?
The process by which different frequencies stimulate neural signals at specific places along the basilar membrane, from which the brain determines pitch
What range of frequencies is the human ear most sensitive to?
1000 to 3500Hz
What part of the basilar membrane moves the most from low-frequency sounds?
Apex (floppy tip)
When the frequency is low, the wide, floppy tip (apex) of the basilar membrane moves the most
What part of the basilar membrane moves the most from high-frequency sounds?
Base (stiff end)
Define “Temporal Code”
The process whereby the cochlea registers low frequencies via the firing rate of action potentials entering the auditory nerve (up to ~5000Hz)
Conductive Hearing Loss
Arises because the eardrum or ossicles are damaged to the point that they cannot conduct sound waves effectively to the cochlea (Middle ear)
In many cases, medication or surgery can correct the problem.
Sensorineural Hearing Loss
Caused by damage to the cochlea, the hair cells, or the auditory nerve, and it happens to almost all of us as we age. (Inner ear)
Sensorineural hearing loss can be heightened in people regularly exposed to high noise levels.
Hearing sensitivity can also be lost in this type, creating “blurry hearing”
Cochlear Implant
An electronic device that replaces the function of the hair cells
The implanted parts include a receiver just inside the skull and a thin wire containing electrodes inserted into the cochlea to stimulate the auditory nerve. Sound picked up by the microphone is transformed into electric signals by the speech processor, which is essentially a small computer. The signal is transmitted to the implanted receiver, which activates the electrodes in the cochlea.
In which type of hearing loss does sound amplification help?
Sensorineural
Musicians have greater plasticity in the ________, compared with non-musicians
Motor Cortex
