CPPS and Voice-Source Parameters: Objective Analysis of the Singing Voice

Introduction. In recent years cepstral analysis and speci fic cepstrum-based measures such as smoothed cepstral peak prominence (CPPS) has become increasingly researched and utilized in attempts to determine the extent of overall dysphonia in voice signals. Yet, few studies have extensively examined how speci fic voice-source parameters affect CPPS values. Objective. Using a range of synthesized tones, this exploratory study sought to systematically analyze the effect of fundamental frequency ( f o ), vibrato extent, source-spectrum tilt, and the amplitude of the voice-source fundamental on CPPS values. Materials and Methods. A series of scales were synthesised using the freeware Madde . Fundamental frequency, vibrato extent, source-spectrum tilt, and the amplitude of the voice-source fundamental were systematically and independently varied. The tones were analysed in PRAAT , and statistical analyses were conducted in SPSS . Results. CPPS was signi ficantly affected by both f o and source-spectrum tilt, independently. A nonlinear association was seen between vibrato extent and CPPS, where CPPS values increased from 0 to 0.6 semitones (ST), then rapidly decreased approaching 1.0 ST. No relationship was seen between the amplitude of the voice-source fundamental and CPPS. Conclusion. The large effect of f o should be taken into account when analyzing the voice, particularly in singing-voice research, when comparing pre and posttreatment data, and when comparing inter -subject CPPS data.