Objective: To examine the usefulness of variation in narrow band spectrogram (NBS) parameters when assessing voice quality. Dynamic range (DR) and frequency range (FR) values are evaluated through a visual analog scale of the spectrum, VAS spectrum (VAS-S).

Methods: This is a retrospective study which involved 20 adults with voice disorders, and 5 healthy controls evaluated by videostroboscopy and acoustic assessment. Sustained /a/ vowel spectrography with different sets of parameters were assessed: FR (0 to 4000 Hz and 0 to 5000 Hz), and three DR values (35,45 and 55dB). A total of 200 spectrograms were evaluated to asses inter and intra rater reliability. Three SLPs experienced with sound spectrography served as blind raters evaluating the NBS through a VAS-S.

Results: A scaled score was obtained for the VAS ratings for each voice sample by averaging the responses from the blind raters in the six spectrogram settings. The inter and intra-rater reliability was evaluated with Intraclass Correlation (ICC). The intra-rater reliability was excellent and good (0.966, 0.963 and 0.837). Inter-rater scores exhibited good to excellent reliability (ICC=0.891). Within the three DR parameters, 45 dB was closer to the average among raters and it was statistically different from the other 2 DRs (both p<0.005). There was no significant difference among the two different FR (p=0.23) or between gender assigned at birth (p=0.99).

Conclusions: Good to excellent inter and intra rater reliability suggests that a VAS can be used to provide a score for a NBS spectrogram. A reliable value for DR, will reduce some of the user-dependency, leading to more consistent assessments between clinicians.