Nonlinear Analyses of Elicited Modal, Raised, and Pressed Rabbit Phonation

摘要

Summary: Objectives/Hypothesis. The purpose of this study was to use nonlinear dynamic analysis methods such as phase space portraits and correlation dimension (D_2) as well as descriptive spectrographic analyses to characterize acoustic signals produced during evoked rabbit phonation.Methods. Seventeen New Zealand white breeder rabbits were used to perform the study. A Grass S-88 stimulator (SA Instrumentation, Encinitas, CA) and constant current isolation unit (Grass Telefactor, model PSIU6; West Warwick, RI) were used to provide electrical stimulation to laryngeal musculature, and transglottal airflow rate and stimulation current (mA) were manipulated to elicit modal, raised intensity, and pressed phonations. Central 1 second portions of the most stable portion of the acoustic waveform for modal, raised intensity, and pressed phonations were edited and then analyzed via phase space portraits, Poincare sections, and the estimation of the D_2. In an attempt to limit the effects of the highly variable and nonstationary characteristics of some of the signals being analyzed, D_2 analysis was also performed on the most stable central 200-millisecond portion of the acoustic waveform. Descriptive analysis of each phonation was also conducted using sound spectrograms.