Smoothed Cepstral Peak Prominence: A Comparison Between Dysphonic and Non-dysphonic Mexican Adults Employing the Praat Software

Background Acoustic vocal analysis provides objective and measurable values for various voice parameters, such as fundamental frequency (F0), shimmer, jitter, and the noise-to-harmony ratio (NHR). In severely dysphonic patients, who present increased variability in glottic cycles and abnormalities in vocal intensity, conventional acoustic analysis is an unreliable predictor of dysphonia. The logarithmic transformation of the vocal spectrum (cepstrum) allows capturing the signal without relying on recording technique, frequency, or vocal intensity. Smoothed cepstral peak prominence (CPPS) is a variable in cepstral analysis that serves as a reliable predictor of dysphonia, being directly proportional to its severity. Objective To determine the mean value of CPPS in continuous speech and sustained vowels in dysphonic and non-dysphonic Mexican adults, with or without laryngeal pathology. Materials and methods Sustained vowel and continuous speech analysis was performed using the Praat software (Version 6.1.15, developed by Paul Boersma and David Weenink, Phonetic Sciences, University of Ámsterdam, https://www.praat.org/) to obtain the smoothed cepstral peak prominence (CPPS) in 51 dysphonic patients with laryngeal pathology and 24 non-dysphonic patients without underlying laryngeal pathology. Frequency perturbation variables such as shimmer, jitter, and NHR were collected. Quality of life was assessed using the 30-item Voice Handicap Index (VHI-30). Results We found significantly lower median CPPS values in patients with laryngeal pathology, both in sustained vowel (6.59, IQR 4.09-9.38, p < 0.001) and in connected speech (4.82, IQR 3.57-6.03, p < 0.001), compared with the non-dysphonic population (sustained phonation: 11.69, IQR 9.26-12.81, p < 0.001; connected speech: 6.38, IQR 0.90-7.09, p < 0.001). Conclusions A low CPPS value is a reliable predictor of underlying laryngeal pathology in dysphonic voices and could be considered for routine screening and diagnosis in patients with vocal pathology.