Instrument-assisted measuring procedures expand the options within phoniatric diagnostics by quantifying the condition of the voice. The aim of this study was to examine objective treatment-associated changes of the recently developed vocal extent measure (VEM) and the established dysphonia severity index (DSI) in relation to subjective tools, i.e., self-evaluation via voice handicap index (VHI-12) and external evaluation via auditory-perceptual assessment of hoarseness (H). The findings for H (3 raters’ group assessment), VHI-12, DSI, and VEM in 152 patients of both sexes (age range 16–75 years), taken before and 3 months after phonosurgery or vocal exercises, were compared and correlated. Posttherapeutically, all of the recorded parameters improved (p<0.001). The degree of H reduced on average by 0.5, the VHI-12 score sank by 5 points, while DSI and VEM rose by 1.5 and 19, respectively. The correlations of these changes were significant but showed gradual differences between H and VHI-12 (r = 0.3), H and DSI (r = −0.3), and H and VEM (r = −0.4). We conclude that all investigated parameters are adequate to verify therapeutic outcomes but represent different dimensions of the voice. However, changes in the degree of H as gold standard were best recognized with the new VEM.

The international nine-item Voice Handicap Index (VHI-9i) is a clinically established short-scale version of the original VHI, quantifying the patients’ self-assessed vocal handicap. However, the current vocal impairment classification is based on percentiles. The main goals of this study were to establish test–retest reliability and a sound statistical basis for VHI-9i severity levels. Between 2009 and 2021, 17,660 consecutive cases were documented. A total of 416 test–retest pairs and 3661 unique cases with complete multidimensional voice diagnostics were statistically analyzed. Classification candidates were the overall self-assessed vocal impairment (VHIs) on a four-point Likert scale, the dysphonia severity index (DSI), the vocal extent measure (VEM), and the auditory–perceptual evaluation (GRB scale). The test–retest correlation of VHI-9i total scores was very high (r = 0.919, p < 0.01). Reliability was excellent regardless of gender or professional voice use, with negligible dependency on age. The VHIs correlated best with the VHI-9i, whereas statistical calculations proved that DSI, VEM, and GRB are unsuitable classification criteria. Based on ROC analysis, we suggest modifying the former VHI-9i severity categories as follows: 0 (healthy): 0 ≤ 7; 1 (mild): 8 ≤ 16; 2 (moderate): 17 ≤ 26; and 3 (severe): 27 ≤ 36.

Voice timbre is defined as sound color independent of pitch and volume, based on a broad frequency band between 2 and 4 kHz. Since there are no specific timbre parameters, previous studies have come to the very general conclusion that the center frequencies of the singer’s formants are somewhat higher in the higher voice types than in the lower ones. For specification, a database was created containing 1723 sound examples of various voice types. The energy distribution in the frequency bands of the singer’s formants was extracted for quantitative analysis. When the energy distribution function reached 50%, the corresponding absolute frequency in Hz was defined as Frequency of Half Energy (FHE). This new parameter quantifies the timbre of a singing voice as a concrete measure, independent of fundamental frequency, vowel color and volume. The database allows assigning FHE means ± SD as characteristic or comparative values for sopranos (3092 ± 284 Hz), tenors (2705 ± 221 Hz), baritones (2454 ± 206 Hz) and basses (2384 ± 164 Hz). In addition to vibrato, specific timbre parameters provide another valuable feature in vocal pedagogy for classification of voice type and fach according to the lyric or dramatic character of the voice.

Patients with unilateral vocal fold cancer (T1a) have a favorable prognosis. In addition to the oncological results of CO2 transoral laser microsurgery (TOLMS), voice function is among the outcome measures. Previous early glottic cancer studies have reported voice function in patients grouped into combined T stages (Tis, T1, T2) and merged cordectomy types (lesser- vs. larger-extent cordectomies). Some authors have questioned the value of objective vocal parameters. Therefore, the purpose of this exploratory prospective study was to investigate TOLMS-associated oncological and vocal outcomes in 60 T1a patients, applying the ELS protocols for cordectomy classification and voice assessment. Pre- and postoperative voice function analysis included: Vocal Extent Measure (VEM), Dysphonia Severity Index (DSI), auditory-perceptual assessment (GRB), and 9-item Voice Handicap Index (VHI-9i). Altogether, 51 subjects (43 male, eight female, mean age 65 years) completed the study. The 5-year recurrence-free, overall, and disease-specific survival rates (Kaplan–Meier method) were 71.4%, 94.4%, and 100.0%. Voice function was preserved; the objective parameter VEM (64 ± 33 vs. 83 ± 31; mean ± SD) and subjective vocal measures (G: 1.9 ± 0.7 vs. 1.3 ± 0.7; VHI-9i: 18 ± 8 vs. 9 ± 9) even improved significantly (p < 0.001). The VEM best reflected self-perceived voice impairment. It represents a sensitive measure of voice function for quantification of vocal performance.