Auditory Perceptual Assessment of Non-Dysphonic Adult Egyptian Voices Using GSLBI Scale: Are they Normophonic?

Auditory-perceptual evaluation remains a cornerstone of clinical voice assessment. However, normative perceptual data for healthy adult voices are limited, particularly in Arabic-speaking populations. Most existing research has focused primarily on dysphonic voices, with comparatively fewer investigations dedicated to non-dysphonic speakers. The GSLBI scale-developed to perceptually assess Grade, Strained, Leaky, Breathy, and Irregular voice qualities-has been validated using dysphonic samples in comparison with non-dysphonic controls. Nevertheless, clinical observations suggest that subtle perceptual deviations may also be present in individuals without persistent vocal complaints. This underscores the importance of establishing normative perceptual benchmarks, as normophonic voices serve as the reference standard for identifying dysphonia. Previous studies have suggested that non-dysphonic voices may exhibit mild perceptual deviations rather than a strict zero-deviation profile. To date, available evidence remains limited but suggests that non-dysphonic voices are not necessarily characterized by a strict "zero-deviation" profile and may exhibit mild perceptual deviations. The present study aimed to characterize the perceptual features of adult Egyptian non-dysphonic voices using the GSLBI scale and to investigate potential age-related differences in perceptual ratings.

This cross-sectional study included 112 Egyptian adults without self-reported vocal complaints. Voice samples were recorded under standardized conditions and included sustained vowels, reading standardized sentences, and spontaneous speech. Four experienced phoniatricians independently evaluated all samples using the GSLBI auditory-perceptual rating scale (Grade, Strained, Leaky, Breathy, and Irregular), in addition to perceptual judgments of pitch and loudness. Participants were stratified into two age groups (<50 and ≥50 years). Statistical analysis was performed using the Chi-square and Fisher's exact tests, with a significance level set at P ≤ 0.05.

Most participants were judged as having no detectable deviation across GSLBI parameters. However, mild deviations were identified by some raters in Grade (0-21.4%), Strained (5.4-28.6%), Irregular (10.7-25.9%), and Pitch (0.9-16.2%). Age-related differences were most prominent in the Irregular parameter, where three of the four raters reported significantly higher deviation rates among participants aged 50 years or older (P = 0.01, 0.004, 0.004).

Using the GSLBI scale, most Egyptian non-dysphonic speakers demonstrated no detectable perceptual deviation; nevertheless, subtle variations-particularly in Strained, Irregular, and Pitch-were observed despite the absence of vocal complaints. These findings suggest that individuals without self-reported vocal complaints may display subtle perceptual variations, and that a strict "zero-deviation" framework does not adequately reflect the natural variability of healthy phonation. The consistent age-related increase in Irregular ratings suggests that this dimension may be sensitive to early presbyphonic changes in the Egyptian population.