Portland State University. Department of Speech Communication
James F. Maurer
Date of Award
Master of Science (M.S.) in Speech: Emphasis in Speech Pathology/Audiology
1 online resource (69 p.)
Stethoscopes, Noise, Heart -- Sounds
A basic relationship between stethoscopic auscultation and background noise interference was reviewed and examined in this study. The principle experimental design of the study questioned whether hospital background noise levels are capable of masking the threshold of detection for auscultated heart sounds. Several cited studies monitoring background noise levels in various hospital locations have reported averages exceeding the U.S. Environmental Protection Agency (EPA) (1974) and World Health Organization (WHO) (1980) recommendations of "quiet", namely 35 to 40 dBA (Falk & Woods, 1973; Hilton, 1985, 1987; Shapiro & Berland, 1972; Turner, et al., 1975; Woods & Falk, 1974) by as much as 46 to 51 dB, i.e., up to 86 dBA (Shapiro & Berland 1972). In addition to the previous query, a review of the literature reflected a lack of implementatory standards regarding the acoustic stethoscopic output and the masking effects of noise during the auscultation process. Specifically, this study ascertained the effective masking level (EML) intensities of two noise environments, white noise and cafeteria noise, for cardiac auscultation through an acoustic stethoscope and an amplified stethoscope. Two principle measurements were employed in the experimental protocol: an objective measurement employing a method of adjustment detection identification task of the EML, and subjective responses solicited by a forced-choice questionnaire. Sixteen normal hearing listener's were selected to participate in the experiment. Objective measures were analyzed using a MANOVA and a Pearson Product Moment Coefficient of correlation. The subjective questionnaire data were analyzed with a two-tailed T-test. All analyses were based on a .05 level of confidence.
Gigstad, Lynda Lynell, "A comparison of an acoustic stethoscope and an amplified stethoscope in white noise and cafeteria noise during cardiac auscultation" (1990). Dissertations and Theses. Paper 3974.