Senior Honors Projects, 2010-2019

Surprisingly small pinna changes affect sound localization

Elizabeth N. Surface, James Madison University


The purpose of this study was to determine the significance of the pinnae in the aid of sound localization. This was a replica study to verify results of a similar study conducted at the University of Virginia prompted by interest from Jared Christophel, MD of the Otolaryngology department at UVA. It was hypothesized if a subject were to participate in a test of sound localization twice, once under normal listening conditions and once with pinnae pinned to their temporal bones by a tiara, their ability to localize sounds would be negatively affected by the slight disturbance to their natural pinnae position. This study was conducted using a computer program designed to emit white noise bursts from one randomly selected speaker among 8 speakers arranged 20 degrees apart in a semicircle around the subject. For each trial, pinned and normal pinnae position, the subject was instructed to select which speaker was activated. The percent correct (PC) and root mean squared of error in degrees (RMS) were measured and averaged to form two dependent variables from each test. Paired-sample t-tests show a significant effect of the tiara on RMS (t9= 2.5, p=. 03), but only an arguably significant effect of the tiara on PC (t9= 1.9, one-tailed p=. 048). The order of trial completion was randomized for each participant, but as subsequent graphs will show, listeners tended to do better on the 2nd test, so the effect of the tiara was more pronounced when that test came first. However, an independent samples t-test was used to show there was no significant effect of which test came first (t8= 1.58, p= .15). In conclusion, this slight disturbance of the pinnae position significantly impacts the ability to localize sounds accurately in the horizontal plane. Thus in relation to relevant professions such as otolaryngology, a patient undergoing an otoplastic operation that alters the state of their pinna may experience outcomes on their localization abilities similar to those found in this study.