Acoustic voice quality index as a potential tool for voice screening

Introduction

To diminish the risk of voice disorders in people who are highly dependent on their voices, such as teachers, vocal screening is important already at the beginning of such individuals’ professional studies. A reliable, specified screening tool is needed. The Acoustic Voice Quality Index (AVQI) has been found to differentiate normal voices from abnormal voices and to serve as a treatment outcome measure. This study investigated whether AVQI could be a screening tool in combination with auditory- and self-perception of the voice to discriminate normal from slightly poor voices.

Type of Study

Experimental.

Methods

Some 128 female teaching students (mean age 26.39 years, SD 9.80 years) with no diagnosed voice disorders participated in this study. They read aloud a text in Finnish, sustained the vowel /a:/, and filled the Voice Handicap Index (VHI) questionnaire. Voice samples were recorded with an AKG C544L headset microphone, iFocusrite soundcard, and Praat software using a 44100 sample rate and 16-bit amplitude quantization. Five expert voice therapists evaluated the samples to determine the grade of dysphonia (G) using a scale of 0–0.5 (=normal), 0.5–1 (=mild), 1–2 (=moderate), and 2–3 (=severe). Three medial seconds of [a:] and the first 31 syllables of the text were analyzed using AVQI script version 03.01 in Praat (5.3.55). The analysis gives one AVQI score per participant (scale 0–10). The AVQI threshold of normal and disordered voices for Finnish speakers is 1.83; a G_mean = 0.0–0.5 and VHI score <19 were considered normal. Statistical analysis was done using the receiver operating characteristic (ROC) curve, Spearman's correlation coefficient, and the independent samples t test.

Results

According to the AVQI results, the area under the curve (A_ROC) was 0.554, which is fair. The Youden index gave a cutoff value of 0.30 with a sensitivity of 85% and a specificity of 81.1%. There were weak but significant correlations between G_mean and AVQI and two AVQI parameters, smoothed cepstral peak prominence and harmonic-to-noise ratio (r = 0.27; −-0.24; −0.20, respectively; |P < 0.05); and between total VHI and AVQI score and cepstral peak prominence (r = 0.21; 0.20, respectively; P < 0.05). Furthermore, the AVQI scores differed significantly between the groups with a VHI total score <19 and ≥19.

Conclusions

AVQI did not differentiate between voices that had been perceptually judged as normal or slightly abnormal, but a combination of perceptual assessment in the form of AVQI and VHI could better screen slightly deviant voices.