목적: The low-to-high spectral ratio(SR) reflects spectral energy distribution of the voice. In clinical and research settings, SR typically uses fixed 4 kHz cutoff. However, evidence is limited on whether this cutoff optimally distinguishes pathological voices. This study examined whether 1-6 kHz SR cutoff adjustment enhances diagnostic sensitivity across speech tasks. 방법:Sustained vowel phonation(SV) and sentence reading(CS) samples collected from individuals with normal voices and those with voice disorders. SR values computed for cutoff frequencies ranging from 1 to 6 kHz. Two-way ANOVA with group and gender factors compared group differences across cutoff points. Correlations between SR and perceptual severity ratings analyzed. Receiver operating characteristic(ROC) analyses evaluated diagnostic utility at each cutoff frequency. 결과:Group differences and classification performance of SR varied significantly depending on cutoff frequency. Certain cutoff points showed higher diagnostic sensitivity than conventional 4 kHz reference. Vowel tasks showed greatest discrimination at 1 kHz cutoff, while sentence tasks showed optimal performance at 5-6 kHz. Correlational analyses revealed SR-perceptual severity relationship depended on cutoff frequency, showing positive correlations at lower points and negative at higher ones. 결론:The diagnostic sensitivity of SR is not fixed to a single frequency cutoff, but varies considerably depending on the chosen cutoff frequency. These findings challenge the traditional use of a single SR cutoff and suggest that task-specific and purpose-driven adjustments of the frequency cutoff can enhance the clinical utility of SR in voice assessment.