Harmonic to noise ratio improvement in oesophageal speech.

BACKGROUND: This manuscript presents oesophageal speech enhancement. Patients who have undergone a laryngectomy as a result of larynx cancer, that is, laryngectomees, have communication problems. Due to removal of the larynx, oesophageal speech has extremely low intelligibility. OBJECTIVE: Thus, it is necessary to process acoustical parameters, such as Harmonic to Noise Ratio (HNR) in order to increase intelligibility. METHODS: The research focused on oesophageal Spanish /a/ phoneme improvement. In order to enhance oesophageal speech two techniques were applied: Kalman filtering and an algorithm which stabilizes the vocal tract poles. Speech enhancement was measured using the MDVP tool. The oesophageal voice database was compiled with the help of the local association of laryngectomees. RESULTS: The results show an average improvement of 4.2 dB in the HNR. Statistically, differences on average between the original and processed voices, (p < 0.001) for HNR parameter were proven to be significant and we therefore conclude that voice quality was improved due to evidence of a higher HNR on average. CONCLUSIONS: As a conclusion, the study confirms oesophageal voice enhancement since speech parameters are closer to the normal average range. Subjectively, the oesophageal breathing noise is reduced substantially, as is reflected in the MOS test.