User:Kmcglynn/Binaural fusion

Wikipedia Proposal: Binaural fusion

Kayleigh McGlynn, Natalie Mella, and Armen Abagyan

Our group’s proposal for the Binaural fusion article is as follows. This proposal outlines the topics that we plan to cover as well as how we plan to organize the article. As our research on binaural fusion continues, we will divide up work by topic, based on which group members feel most comfortable writing about which topics. Each group member will be assigned to writing different sections or topics for the article, but all group members will be expected to review each other’s work. Reviewing each other’s contributions will ensure consistency in wording and phrasing throughout the article. Additionally, this will allow group members to share with each other if they find new information pertaining to someone else’s assigned topic.

Introduction

Binaural fusion, also referred to as binaural integration, is the process responsible for the ability of a listener to perceive a speaker’s distance. Without it, one can not tell where the source of a speaker’s voice is coming from. Binaural sound localization is based on interactions of synaptic inputs from both ears. This process permits an individual to focus on a single speaker when many speakers are present. Binaural fusion also enhances an individual’s ability to understand the speech of one person in noisy environments or in environments with multiple speakers (sound segregation).

As our research continues, we plan to add more information to provide a more complete overview of the entire article.

Background: Sound Localization

Interaural time difference (ITD) results because the farther away the source is, the longer it takes for a sound to reach the ear, and the time to reach each of the two individual ears can be different. Interaural intensity difference (IID) results because of the head shadow effect, which prevents some of the intensity of the incoming sound from reaching the ear turned away from the direction of the sound source. ITD and IID work in complementary frequencies for simple sounds.

Anatomy

Cochlea

The cochlea is a spiral-shaped cavity in the ear responsible for the auditory portion of the inner ear. It serves as the auditory receptor surface.

We will use an image to clearly depict this anatomical function.

Superior Olivary Complex

The superior olivary complex (SOC) refers to a collection of brainstem nuclei that are important for hearing. Specifically, this complex is an important component of the ascending and descending auditory pathways. Initial binaural processing occurs in the SOC. The SOC is composed of: the lateral superior olive (LSO) and the medial superior olive (MSO). Afferent fibers of the right and left auditory pathways converge at the SOC.

We will use an image or diagram to depict this anatomy.

Mechanism

Integration of sound stimulus occurs as a result of analyzing frequency (pitch), intensity, and spatial localization of sound sources. Binaural sound localization mechanisms are based on interactions of synaptic inputs from both ears.

We plan to greatly expand on the mechanism of binaural fusion as our research continues.

Superior Olivary Complex

The Superior Olivary Complex is responsible for the processing of binaural information entering into the brain stem from cochleae. The timing and the motif of action potentials propagating into the brain stem provide neurological instruction regarding the angular orientation of sound in space. The Superior Olivary Complex participates in rapid processing and high levels of conduction of action potentials. This contributes to the preservation of timing information which is central in Binaural processing. Binaural processing depends on the interactions of excitatory and inhibitory inputs in the LSO and MSO of the SOC. Binaural processing in the SOC is regulated by GABA_B receptors.

Lateral Superior Olive

Analysis in the LSO is projected to the midbrain.

Medial Superior Olive

The MSO contains cells that function in comparing inputs from the right and left cochlear nuclei.

Diseases and Disorders

We have found some information in regards to cochlear implants and their role in restoring hearing as well as binaural fusion functions. We have not found many details about diseases and disorders of binaural fusion, but we believe that this type of information is important, and we are working on researching it further with hopes of adding information about diseases, disorders, and treatments to the article. Organization of this section will evolve as we continue research. We are also interested in researching whether there are tests to evaluate whether or not a person has binaural fusion or integration functioning properly.

References

1. Eldredge, D.H., and Miller, J.D. (1971). Physiology of hearing. Annu. Rev. Physiol. 33, 281-310.

2. Grothe, B., and Koch, U. (2011). Dynamics of binaural processing in the mammalian sound localization pathway--the role of GABA(B) receptors. Hear. Res. 279, 43-50.

3. Litovsky, R., Colburn, H.,Yost, w., et al. (1999). The Precedence Effect. Journal of the Acoustical Society of America, 106(4), 1633-1654.

4. Masterton, R., Imig, T. (1984). Neural Mechanisms for Sound Localization. Annual Review of Physiology, 46: 275-287.

5. Sayers, B., Cherry E. (1957). Mechanism of Binaural Fusion in the Hearing of Speech. Journal of the Acoustical Society of America, 29(9), 973-987.

6. Simon, E., Perrot, X., and Mertens, P. (2009). Functional anatomy of the cochlear nerve and the central auditory system. Neurochirurgie 55, 120-126.