Acoustic Analysis of Aperiodic Voice: Perturbation and Nonlinear Dynamic Properties in Esophageal Phonation

Abstract

Objectives/Hypothesis-Esophageal voice is a method of communication after total laryngectomy. Previous research suggests that perturbation analysis may inaccurately measure aperiodic voices and that nonlinear dynamic methods may be more appropriate for analyzing signals of this type. Therefore, we hypothesized that nonlinear dynamic analysis would be more capable than perturbation parameters for reliable measurement of the aperiodic esophageal voice.Study Design-Acoustic comparison of esophageal and normal voice cohorts using nonlinear dynamic and perturbation measures.Methods-Twenty subjects in two age-matched groups participated in the study. Jitter, shimmer, signal-to-noise ratio, correlation dimension, and second-order entropy were measured from audio recordings of subjects' voices.Results-Jitter and shimmer values were significantly higher for esophageal voices and signalto-noise ratio values were significantly lower for esophageal voices than for normal voices. Error count values, which indicate perturbation analysis reliability, were 0 in normal voices and significantly higher in esophageal voices. Error was attributable to signal aperiodicity and demonstrated that perturbation analysis yielded questionable results for esophageal voice. However, nonlinear dynamics measures analyzed both cohorts reliably and indicated that esophageal voice was significantly more chaotic than normal voice. Conclusions-The results demonstrated the capability of nonlinear dynamic methods to reliably quantify both aperiodic and periodic signals and to differentiate normal from esophageal voices. It is suggested that nonlinear dynamic analysis be used preferentially for acoustic characterization of aperiodic voices such as esophageal voice. Future research should focus on clarification of perturbation analysis reliability and further application of nonlinear dynamic measures to aperiodic voices.

Cepstral, Spectral and Time-Based Analysis of Voices of Esophageal Speakers

“…This finding is consistent with that of previous studies [4,23,24] and reflects the inferior vibratory characteristics of the PE segment as compared to the vocal folds [5]. The higher values of noise variables are attributed to the fact that the aperiodic and variable voice characteristics of esophageal speakers make it difficult to adjust pitch and accent and pose difficulty in securing an adequate amount of air necessary to produce a stable voice [8,9]. …”

“…Esophageal speech involves sound production through vibration of the pharyngoesophageal (PE) segment by expelling air through the esophagus; in principle, this action is the same as that of a burp. Esophageal speech can imply a serious problem with voice quality, in particular owing to the absence of a vocal organ and the lack of air energy source necessary for speaking [5,6,7,8]. …”

“…In worldwide studies that used cepstral analysis, perturbation analysis was found to have some limitations in reflecting the acoustic characteristics of esophageal speakers [5,6,7,8,10,11]. To our knowledge, the voice and the degree of voice quality of patients with laryngectomies has never been analyzed with CPP measures using ADSV (Analysis of Dysphonia in Speech and Voice).…”

Análise acústica não linear da voz pós laringectomia parcial

“…( LITTLE et al, 2007LITTLE et al, , 2011MACCALLUM et al, 2009 A partir desta padronização dos tipos de sinais de voz, fica evidente que a análise acústica da voz convencional é confiável para uma pequena parcela dos distúrbios vocais onde, as alterações são discretas. Por esse motivo a análise de sinais de vozes dos Tipos 2 e 3 apenas serão confiáveis por meio das análises acústicas não lineares (ANL).…”

“…Há evidências substanciais de que a vibração das pregas vocais é um processo altamente não linear e que produz efeitos combinados de eventos biomecânicos e aerodinâmicos com ricos comportamentos vibratórios irregulares, tais como bifurcação e caos. Estas evidências têm sido mais frequentemente utilizadas na compreensão dos distúrbios vocais por meio de métodos dinâmicos não lineares (MACCALLUM et al, 2009).…”