Detection system of pharyngeal tonsil hypertrophy: Optimal cepstral coefficient for detecting anti-formant

Pharyngeal tonsil lymphoid tissue hypertrophies as acquired immunity improve during childhood. Identifying pharyngeal tonsil hypertrophy at an early stage is important for treatment, as hypertrophied tissues may lead to sleeping and breathing disorders. Therefore, we propose a non-invasive method for detecting pharyngeal tonsil hypertrophy using only speech sounds. This paper focuses on an anti-formant caused by the obstruction of the pharyngeal cavity. Anti-resonance frequency was recognized in the spectral envelope and was calculated using the cepstral coefficient. Therefore, antiformant differences are expected to contribute to the identification of pharyngeal tonsil hypertrophy. However, the optimal cepstral coefficient has not yet been clarified. In this study, the optimal cepstral coefficient was determined using statistical analysis and experiments. The efficacy of the proposed method was demonstrated using acoustic parameters for speech sounds formed with and without pharyngeal tonsil hypertrophy.