Acoustic Characteristic Of Vocal Nodules

With the continuous improvement of the level of industrialization in China, there is anincreasing incidence of laryngeal disease. At the same time, those whose occupationsrequired long-term use of voice, show the tendency of a normal occupational disease. Thelaryngoscope examination which is invasive is the most commonly used method to detectthe throat disease.However, the method is complex to opperate, and the patient feelsdiscomfort or pain. Some are even unwilling to accept the examination and it often resultsin delaying treatment time. Moreover, this method, in which endoscopic fiber pipe isdirectly inserted into the human throat, is at a risk of cross infection if equipmentdisinfection is not done completely. So, considering the need to improve the method ofdetecting throat disease and the reduction of costs of the examination, a new secure,non-invasive, time-saving, low-cost method is especially necessary.In the previous pathological voice detection work and laryngeal disease diagnosisbased on acoustic signal, researchers primarily focused on the classification andidentification of the healthy voice and pathological voice, most of which are statisticalmethod without any physical-mathematical model. This result in the past researchesmainly paying attention to the signals, while ignoring the fact that signal is the reflection ofphysical properties of the object. Indicators that have been raised are poor in uniformity,reproducibility and accuracy, thus new indicators containing pathological significance areneeded.This article uses a steady vowel as the research object.On the basis of the humansound production principles in which vocal cord is simplified as a general model of idealfree string, the solution of the wave equation and the physical changes of the vocalsymmetry and coupling, the intrinsic characteristic of vocal nodules was established. Thefrequency difference was proposed as a characteristic of vocal nodules in the frequencydomain analysis.In the course of the study, a system including acoustic signal acquisition, storage andanalysis has been established. In order to have a better management of voice signal data, adata storage system specific for voice collection and a series of practical digital signal analysis graphical tools, which contains commonly used functions in signal analysis, hasbeen developed. So, it makes the system more specialized and targeted. The results showthat the spectrum of the acoustic signal of patients in most cases will indeed produce afrequency difference phenomenon. This feature, to some extent, can distinguish betweenthe normal group and pathological group. It will have positive implications for furtherstudy of the acoustic signal characteristics of vocal nodules.