Study On The Correction Method Of Pathological Voice Formants By Using LSP

Voice, an essential factor for human communication. The quality of a voice directly affects people’s communication. The vocal organs have organic lesions and a pathological change in nerves because of over-use. The formant is an important voice parameter from the vocal tract model, and it is also an important parameter in the correction of the voice.LSM-EBT is proposed through the analysis of pathological voice formants by this paper.In this paper, we mainly study the pathological voice formants based on Line Spectral Pairs. The correction work based on LSM-EBT mainly uses the ability of tracking. This method modifies the distance of LSF so as to achieve the purpose of correcting formants. The formant extraction method based on LSP is to quickly find the related LSF.In this method, the range that represents the corresponding relationship between the distance of LSF and formants(the first and the second) is the smallest of the four distances between the LSF. And the range in the pathological voice is not the same. The range is corrected according to the pathological voice.Kruskal-Wallis test is used to analyze the difference between the formants of different pathological types and the normal voice. According to the difference of the distribution of formants, the method of LSM(Line spectral pairs Segment fixed value Migration) is proposed. By analyzing the shift value, different migration parameters are used in the formants of different range from different pathological voices. The first formant and the second formant are effectively modified.However, LSM still does not have the ‘flexibility’. In the summary, LSM is still not very good for some formants from different pathological voices. The frequency bending function is analyzed. Then, EBT(Extended Bilinear Transformation) is applied to the further modification of the pathological formants. The correction results is improved.Comparison of pole placement method, line spectral distance measure in hyperthyroidism, polyps, nodules, edema of the four kinds of pathological voice are reduced by 59%, 62% and 63%, 47%. KL distance in hyperthyroidism, polyps, nodules, edema of the four kinds of pathological voice are increased by 167% and 125%, 158% and 88%. Comparison of contrast setting offset method, line spectral distance are reduced by 42%, 39%, 38%, 32%, also the KL distance are increased by 84%, 47%, 63%, 66%. The result is given to illustrate the validity of the formant correction method.