title: Reliability of objective voice measures of normal speaking voices.
abstract: OBJECTIVE
  To determine the reliability of objective voice measures used commonly in clinical practice.
  
  
  METHODS
  Eighteen healthy volunteers (nine males and nine females).
  
  
  METHODS
  Objective voice measures were performed on 18 healthy volunteers on 10 occasions under similar conditions over a 30-day period. Consistency of measures was analyzed to determine reliability.
  
  
  RESULTS
  Using currently accepted normative values, intraclass correlation coefficients were moderate (>0.6) for consistency over the 10 testing sessions for most acoustic measures that do not depend on intensity, measures of laryngeal efficiency, and perturbation measures of fundamental frequency (F0) for both genders. For females, cepstral peak prominence (CPP) had moderate reliability, whereas for males, the smoothed CPP was reliable. Other than F0, none of the perturbation measures are reliable for females. However, jitter, relative average perturbation, and standard deviation of F0 are reliable for males. Noise-to-harmonic ratios (NHRs) had the lowest consistency of all measures over the course of the 10 sessions.
  
  
  CONCLUSIONS
  Clinicians should be cautious in their use of acoustic voice measures that depend on the intensity and in their use of most perturbation measures. NHR was found to be the least reliable measure. Additionally, the reliability of CPP measure varies by gender. Understanding the degree of within-person variability on some objective voice measures and whether that variation is due to biological differences or measurement error will lead clinicians to consider the need for a more standardized testing protocol. Additional research is needed to investigate what factors within the testing protocol and/or changes to the measurement instruments may lead to more consistent test results.
authors.affiliation: Department of Surgery, Brown University, Providence, Rhode Island, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Leong
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Hawkshaw
authors.forename: Dimiter
authors.initials: D
authors.lastname: Dentchev
authors.forename: Reena
authors.initials: R
authors.lastname: Gupta
authors.forename: Deborah
authors.initials: D
authors.lastname: Lurie
authors.forename: Robert T
authors.initials: RT
authors.lastname: Sataloff
mesh_terms: D000162:Acoustics; D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007830:Larynx / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010699:Phonation; D015203:Reproducibility of Results; D012737:Sex Factors; D013061:Speech Acoustics; D013068:Speech Production Measurement; D013997:Time Factors; D014833:Voice Quality; D055815:Young Adult