This paper reviews recent evidence regarding the validity and reliability of acoustic voice analysis in routine clinical assessments. The current role of jitter and shimmer, the most-used indices, and how their clinical application might be improved are evaluated.
Even though the evidence is limited, acoustic analysis is widely used to assist differential diagnosis, documentation and evaluation of treatment for clinical voice disorders. Recent clinical data have not shown that jitter and shimmer are absolute or independent indices of voice pathology or perceptual hoarseness. However, in pretreatment and posttreatment comparisons within patients, acoustic analysis might have value as an outcome measure.
Yet, the true value of clinical acoustic analysis might be masked by the confounding effects due to assessment system, gender, vowel and especially speaking voice intensity.
The validity of acoustic assessments in clinical applications remains unproven. Measurement reliability is still limited and might be greatly improved with relatively simple changes and consensus in measurement protocols and techniques. For instance, clinical assessment procedures and current normative values would have to be revised considering gender and vowel. Thus, future research might establish the validity and potential of clinical acoustic assessments.
aDepartment of Phoniatry and Speech Pathology, Clinic for Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland
bRegional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, Great Britain, UK
Correspondence to Meike Brockmann-Bauser, MSc, Department of Phoniatry and Speech Pathology, Professional Head of Speech Pathology, Clinic for Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Frauenklinikstrasse 24, 8091 Zurich, Switzerland Tel: +41 44 255 5830; fax: +41 44 255 4424; e-mail: firstname.lastname@example.org