# Analysis of Phonetic Segments of Oesophageal Speech in People Following Total Laryngectomy
## 1 Introduction  
According to the Head Office of the National Health Fund, Department of Analyses and Innovation [1], laryngeal cancer is the most common malignant tumour among head and neck cancers. In the case of a very advanced neoplastic disease, a laryngectomy is necessary [2, 3, 4, 5]. The consequence of this surgical procedure is the loss of the complete ability to communicate with the physiological voice. However, a patient deprived of a larynx has a chance to learn substitute speech during phoniatric rehabilitation. Therefore, the analysis of oesophageal speech is a very important research issue. Control of the course of the rehabilitation process should be supported by an observation of the physical features of speech. For this purpose, the values of speech descriptors of sick and healthy people are extracted in order to analyze their numerical differences. Professional methods of Signac processing and analysis, in particular acoustic methods, provide several options for assessing the quality of the speech signal, enabling multilateral analysis. Appropriately applied methods of speech analysis allow for the definition of a set of features that will determine the physical pattern of oesophageal speech [6, 7]. In this paper, an attempt was made to analyze the voices of patients after total removal of the larynx (laryngectomy). The results of the tests will support the process of speech rehabilitation in order to increase the quality and reduce the time for complete rehabilitation. Speech rehabilitation of people following total laryngectomy can be carried out using three options [6, 7]:1. Oesophageal speech: This is a kind of substitute speech following laryngectomy. After a laryngectomy, the folds of the esophageal mucosa may act as a sound source of sound. This is the so-called pseudoglottis in the oesophagus. During oesophagael speech, it is necessary to swallow small amounts of air, which then comes back up via \"burping\". The column of swallowed air causes the oesophagus to vibrate and generate sound, which is modified by the tongue and lips to form words. The advantages of oesophageal speech is are: * Non-surgical method; * Hands-free talking; * Closest to physiological speech; * No need to implement a foreign body. Disadvantages of oesophageal speech are: * Learning takes a lot of time and must be intensive; * Not all people are able to master this method well; * Speech may be incomprehensible; * Speaking in short sentences and at a slower pace--having to swallow air while speaking. 2. Speaking with a voice prosthesis provides the most natural-sounding and easiest-to-understand voice. The prosthesis is placed between the oesophagus and the trachea during a total laryngectomy procedure. The prosthesis has a one-way valve that opens during speak and closes during breathing and eating. When speaking, it is necessary to close the valve with a finger. There are many models of voice prostheses, such as Provox. The advantages of voice prostheses are: * Ability to speak immediately after a laryngectomy; * Greater speech efficiency (no need to swallow air); * Cleaner speech. The disadvantages of voice prostheses are: * Need to implant a foreign body, which may result in tinea or infections; * Periodic replacement; * Occurrence of leaks around the prosthesis; * Spontaneous prolapse of the prosthesis; * Appearance of inflammation. 3. Electrolarynx speech--this is an electrolarynx device. This method requires the use of a hand-held device which, when applied to the neck, generates vibrations that are then shaped by the tongue and mouth into speech. The voice produced by this method sounds very artificial and the modulation depends on the device used. Advantages: * Easy- to- master speech; * Non-surgical method. Disadvantages: * The artificial sound of speech; * The need to wear the device; * The need to use the hand when speaking; * Periodic service of the device required.