gms | German Medical Science

28. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie e. V.
2. Dreiländertagung D-A-CH

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie e. V.
Schweizerische Gesellschaft für Phoniatrie; Sektion Phoniatrie der Österreichischen Gesellschaft für HNO-Heilkunde, Kopf- und Halschirurgie

09.09. - 11.09.2011, Zürich, Schweiz

Do jitter and shimmer measure perceptual hoarseness?

Vortrag

  • corresponding author presenting/speaker Meike Brockmann-Bauser - Abteilung Phoniatrie und Klinische Logopädie, Klinik für Ohren-, Nasen-, Hals- und Gesichtschirurgie, Universitätsspital Zürich, Zürich, Switzerland
  • author Paul N. Carding - Department of Speech and Voice, Freeman University Hospital, Newcastle upon Tyne, Great Britain
  • author Michael J. Drinnan - Regional Medical Physics Department, Freeman University Hospital, Newcastle upon Tyne, Great Britain

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie. 28. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie (DGPP), 2. Dreiländertagung D-A-CH. Zürich, 09.-11.09.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. Doc11dgppV17

DOI: 10.3205/11dgpp26, URN: urn:nbn:de:0183-11dgpp264

Published: August 18, 2011

© 2011 Brockmann-Bauser et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Abstract

Background: Instrumental acoustic analysis is widely used to assess voice disorders and has been described as an objective measurement of voice quality [4]. However research provides contradictory evidence regarding the correlation between perceptual voice assessments with jitter and shimmer [3], [2]. Therefore this study investigates if jitter and shimmer relate to the severity of perceptual hoarseness.

Methods: For this cross-sectional study thirty-three patients with head and neck cancer were recorded before and after radiotherapy while saying a prolonged /i/ for 6 seconds. Perceptual assessment was done by GRBAS scale. The mean overall impression of hoarseness (=“G”) of 2 voice experts was correlated with jitter (%) and shimmer (dB) as determined by PRAAT.

Results: Mean jitter (j) and shimmer (s) were lowest for voices rated GRBAS G0 [j0=0.47(0.36), s0=0.27(0.09)] and higher in voices rated G1 [j1=0.65(0.54), s1=0.39(0.17)] and G2 [j2=0.92(0.78), s2=0.42(0.25)]. For all voices together a moderate correlation between shimmer and G was observed (r=0.25). However in dysphonic voices only (G=1) there was no correlation with shimmer (r=0.03). The majority of pathological voices had jitter and shimmer within the range of normal sounding voices. Also G1 and G2 voices could not be distinguished on the basis of jitter and shimmer.

Discussion: Among the pathologic voices there was no clear association of jitter or shimmer with dysphonia severity. Further by using jitter or shimmer dysphonic voices could not be distinguished from normal voices. Therefore we conlcude that neither jitter nor shimmer are an objective index of perceptual hoarseness. Future research should establish the role of jitter and shimmer in the assessment of disordered voices.


Text

Background

Instrumental acoustic analysis is widely used to assess voice disorders and to describe intervention success [3], [4]. In indicating pitch (jitter) and amplitude (shimmer) perturbation, it has been suggested that jitter and shimmer objectively measure different aspects of perceptual dysphonia [5], [7], [8]. However previous reports disagree on the exact nature of the relation and have associated perceptual “hoarseness” with increased jitter [7] and/or shimmer [5]. Further other authors contradict this and suggest that there is no relation between instrumental acoustic and perceptual assessments [1], [2]. Therefore this study investigates if jitter and shimmer relate to the severity of perceptual hoarseness in voice patients.

Methods

In a cross-sectional single cohort study thirty-three patients with head and neck cancer were recorded before and after radiotherapy while saying a prolonged /i/ for 6 seconds. 61 recordings were assessed by instrumental and perceptual analysis. The instrumental acoustic parameters jitter (%) and shimmer (dB) were determined with PRAAT [9]. Perceptual voice analysis was done by 2 voice experts using the Grading-Roughness-Breathiness-Asthenia-Strain scale (GRBAS) [6]. Thereafter the mean overall impression of hoarseness (as indicated by “G“) of the 2 voice experts was correlated with jitter and shimmer.

Results

Mean jitter (j) and shimmer (s) were lowest for voices rated GRBAS G0 [j0=0.47(0.36); s0=0.27(0.09)]. These patients define the jitter and shimmer range we would expect in normal sounding voices. Both mean jitter and shimmer were higher in the voices rated G1 [j1=0.65(0.54); s1=0.39(0.17)] and G2 [j2=0.92(0.78); s2=0.42(0.25)]. However, as indicated by Figure 1 [Fig. 1], this was due to several patients with extremely high voice perturbation. In the present study the majority of pathological sounding voices had jitter and shimmer within the range of the normal voices (G0). Also dysphonic voices rated G1 and G2 could not be distinguished on the basis of jitter and shimmer. Consequently, for all voices together a moderate correlation between shimmer and G was observed (r=0.25; p=0.05). This was similar for jitter and G in all voices (r=0.27; p=0.04). However in dysphonic voices only (G≥1) there was no clear correlation with increasing shimmer (r=0.03; p=0.9) or jitter (r=0.17; p=0.3).

Discussion

Among pathologic voices, as measured by G of the GRBAS scale, there was no clear association of jitter or shimmer with dysphonia severity. Further it was not possible to reliably distinguish normal from pathologic sounding voices by jitter or shimmer. Therefore we conclude that neither jitter nor shimmer are an objective index of perceptual hoarseness. This might be explained by the low reliability of instrumental acoustic measurements in more irregular voice signals [2]. Nevertheless jitter and shimmer might provide clinically valuable information in patients with normal sounding voices. Future research should establish what jitter and shimmer might indicate in these patients and describe how this could be applied in voice clinics.


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