Enhancement of Shimmer in oesophageal speech using different wavelets

This paper presents an oesophageal speech enhancement algorithm using different wavelet approach. Such an exceptionally special type of voice is due to the laryngectomy undergone by those persons with larynx cancer. An oesophageal voice has extremely low intelligibility. This work proposes a method to improve its quality, which consists of enhancing the Shimmer parameter using Discrete Wavelet Transform (DWT) and it has been tested with different mother wavelets. By taking advantage of the Wavelet Transform´s special time-frequency properties, a corrective algorithm in the form of a wave is applied for the signal intervals in which the shimmer measurement goes beyond normal levels. Therefore, an atomized control of the signal peaks is carried out, having an effect on the normalization of the shimmer. The final speech improvement has been measured with the help of Multidimensional Voice Program (MDVP) [7] tools.