Spectral moment analysis of unilateral vocal fold paralysis.

Many acoustic measures have been used to assess and track the voices of patients with voice problems. Some of these measures rely on the accurate measurement of fundamental frequency to produce reliable results. Patients with voice disorders often produce voices with considerable quasiperiodicity or aperiodicity. There are other measurements that do not depend on the accurate tracking of fundamental frequency by computing the spectrum of the sound and comparing different parts of the spectrum. The moments of the spectral distribution may also be important measurements to use in patients with voice problems. Several studies have reported good results using these measures to track treatment progress. In this study, spectral moments were used to assess the effectiveness of two treatment approaches in patients with unilateral vocal fold paralysis (UVFP). Twenty-six patients with UVFP and dysphonia (16 female and 10 male patients) were studied. Thirteen underwent surgery to improve their voice, whereas the other 13 received voice therapy. The patients were recorded at three time intervals: before the start of treatment, about 1 month after treatment has been completed, and at 3 months after treatment. They produced three types of speech material, vowels /ah/ and /oo/ and a simple sentence. The first four spectral moments (mean, standard deviation, skewness, and kurtosis) were computed from the long-term average spectrum. Severity of voice dysphonia was rated on a 11-point scale ranging from 0 (normal) to 10 (aphonic). There were no statistical differences between males and females for any of the four moments. There was also no difference between the two treatment types. There were differences among the three types of speech material for moments 1 and 3. There were also differences for moments 1, 2, and 3 for the three treatment conditions with most of the differences occurring between the pretreatment and first posttreatment condition. Severity of dysphonia decreased significantly from the pretreatment to either of the two posttreatment conditions. Spectral moments appear to be viable acoustic measurements to use to assess the effects of treatment on the voice of patients with UVFP.

Evaluation of stroboscopic signs.

OBJECTIVE: Clinicians interpret the stroboscopic examination by systematically rating several parameters or "signs." This can be time consuming and experience dependent. The significance of each of these signs is unknown. Some signs may be redundant, whereas others may be more independent, thus reflecting a unique aspect of the exam assessment. We wanted to determine which stroboscopic signs are more independent and clinically relevant. This may lead to a more efficient and reliable method of stroboscopic exam evaluation. STUDY DESIGN: Retrospective. METHOD: One hundred and eighty one consecutive adult patients with dysphonia of various pathologies were studied. Severity of dysphonia was judged, and a set of seven stroboscopic signs for each stroboscopic exam was rated by our voice team. A principal component factor analysis was performed, and the two factors that accounted for the most variance in the original rating data were determined. These two independent factors were then investigated for clinical usefulness. RESULTS: Several individual stroboscopic signs of vocal fold vibration correlated with the "Vibration Factor" (VF) (mucosal wave, amplitude, vibratory behavior, and periodicity) and the vocal fold edge correlated with the "Edge Factor" (EF). Scores for VF and EF were used to differentiate between general categories of vocal fold pathology and related to the severity of dysphonia. Severity of dysphonia correlated with the VF to a greater degree than the EF. Furthermore, these two factor scores could be accurately estimated using only three stroboscopic signs (amplitude, vibratory behavior, and edge). CONCLUSION: The results of the study support the concept that a small set of stroboscopic ratings is an adequate representation of the information derived from the original, more comprehensive sign rating protocol. A focused rating system may provide an efficient method for stroboscopic evaluation, contributing to the differentiation of various vocal fold pathologies and correlating to clinician ratings of severity of dysphonia.

The effect of head position on glottic closure in patients with unilateral vocal fold paralysis.

The present study was designed to assess the effect of head position on glottic closure as reflected in airflow rates (open quotient and maximum flow declination rate), in patients with unilateral vocal fold paralysis. Ten patients, 2 males and 8 females ranging in age from 40 to 75, with a mean age of 57.3, served as subjects. Airflow measures were taken during sustained phonation of two vowels (/i/ and /a/) in 3 head positions (center, right, left). Vowels /i/ and /a/ were produced at subject's comfortable pitch and loudness, with random ordering of both vowel order and head orientation. Subjects were trained to focus eye gaze on right and left markers (70-degree angle) and a central marker at eye level directly in front of the subject. Theoretically, if turning the head during phonation alters the laryngeal anatomic relationship by bringing the vocal folds in closer proximity to one another, then airflow rate should lessen. Our results indicate that head position does not improve glottic closure in these patients, which is in contrast to previously published research.(1) Our results question the utility and underlying theoretical construct for the use of head turning as a therapeutic technique for improvement of voice in patients with unilateral vocal fold paralysis.