Introduction
The human auditory system is incredibly accurate in identifying signal content, location, and meaning through discrete neurological processes. The accuracy of these processes begins at the external, anatomical portions of the auditory pathway: the pinna and ear canal. The pinna serves to collect sound from the environment and generate direction-dependent cues through spectral transformations (Hofman, et al, 1998; Raykar, et al, 2005). Sounds that are funneled into the ear canal contain range of frequencies that are amplified and attenuated. This interaction of complex sound waves, based on the unique shape of an individual’s pinna, results in a transfer function used for localization in the vertical plane (Hofman, et al, 1998, p. 417). There is evidence that the spectral notches and peaks formed when sound interacts with the pinna are a key component to localization of sound in the vertical plane (Raykar, et al, 2005, p. 364). The spectral changes caused by reflections of sound waves on the unique curves of the pinna are referred to as “spectral patterning”. This occurs primarily in frequencies above 6 kHz, as the wavelength of the sound is short enough for it to interact with the pinna. This indicates that sound localization is influenced most by high-frequencies (Moore, 2007, p. 186).
Each individual ear is unique and provides frequency information not offered by any other facet of the auditory pathway. The distinctive curvature and overall shape of the pinna aids in shaping complex signals to determine spatial information by integrating the frequency transforms for both ears. Therefore, it is important to be capable of receiving sound binaurally to accurately locate the signal in space and to reduce ambiguity withi...
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Works Cited
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Cochlear Implants only restore very limited audibility. When described by formerly hearing Deaf people they compare it to hearing underwater, “fuzzy and timbre” yet still able to discern some
“Music is perpetual, and only the hearing is intermittent,” wrote the iconic American essayist, poet and philosopher Henry David Thoreau, a lofty proclamation that inspired my focus to help those with hearing loss through restoration. After a winding journey in search for an academic focus, I discovered that audiology is far more than just aiding deaf or hard of hearing individuals, but restoring balance, managing loss through therapy, and discovering new research techniques that may involve auditory neuropathy spectrum disorder. After arriving at my destination, I also learned that it is my responsibility as a future audiologist to be a leader, to work hard toward achieving a better future for myself, and a better world for humanity at large. This vision drives my aspiration to join the University of South Florida’s graduate audiology program this coming fall, and continue my examination of clinical audiology as a member of your community.
Audition is a complex process that involves multiple areas of the brain. To be able to hear sound is just the beginning. Understanding speech and appreciating music requires an intensive and complex network of processes still yet to be understood. Many auditory processing deficits have been discovered with varying degrees of specificity and severities. A whole area of research has been dedicated to finding solutions to these auditory deficits that many ...
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The mechanical motions of the ossicles directly vibrate a small membrane that connects to the fluid filled inner ear. From this point, vibration of the connective membrane (oval window) transforms mechanical motion into a pressure wave in fluid. This pressure wave enters and hence passes vibrations into the fluid filled structure called the cochlea. The cochlea contains two membranes and between these two membranes, are specialized neurons or receptors called Hair cells. Once vibrations enter the cochlea, they cause the lower membrane (basilar membrane) to move in respect to the upper membrane (i.e. --the tectorial membrane in which the hair cells are embedded). This movement bends the hair cells to cause receptor potentials in these cells which in turn cause the release of transmitter onto the neurons of the auditory nerve. In this case, the hair cell receptors are very pressure sensitive. The greater the force of the vibrations on the membrane, the more the hair cells bend and hence the greater the receptor potential generated by these hair cells.
National Institute on Deafness and Other Communication Disorders. (November 2002). Retrieved October 17, 2004, from http://www.nidcd.nih.gov/health/hearing/coch.asp
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It is a well established fact, that during the fetal period, the brain undergoes extensive developmental changes, with new synapses being formed continuously in response to external cues being delivered to the fetus. This development of neuronal connectivity enables the fetus to recognize and analyze complex information. This is especially true in the development of the auditory nervous system. A strong model of the auditory development in response ...
M.M. Merzenich, J. K. (1983). Topographical reorganization of somatosensory cortial areas 3b and 1 in adult monkeys following restrictive deafferentation. Neuroscience, 33-55.
The ear is looked upon as a miniature receiver, amplifier and signal-processing system. The structure of the outer ear catching sound waves as they move into the external auditory canal. The sound waves then hit the eardrum and the pressure of the air causes the drum to vibrate back and forth. When the eardrum vibrates its neighbour the malleus then vibrates too. The vibrations are then transmitted from the malleus to the incus and then to the stapes. Together the three bones increase the pressure which in turn pushes the membrane of the oval window in and out. This movement sets up fluid pressure waves in the perilymph of the cochlea. The bulging of the oval window then pushes on the perilymph of the scala vestibuli. From here the pressure waves are transmitted from the scala vestibuli to the scala tympani and then eventually finds its way to the round window. This causes the round window to bulge outward into the middle ear. The scala vestibuli and scala tympani walls are now deformed with the pressure waves and the vestibular membrane is also pushed back and forth creating pressure waves in the endolymph inside the cochlear duct. These waves then causes the membrane to vibrate, which in turn cause the hairs cells of the spiral organ to move against the tectorial membrane. The bending of the stereo cilia produces receptor potentials that in the end lead to the generation of nerve impulses.