1、 Theoretical explanation of vibrato

Tremol is a key technique in vocal singing, with a frequency of approximately 6-7Hz, which creates a pleasant sensation for the audience. The lack of vibrato can make the sound appear stiff, while rich vibrato gives the sound lively, pleasant and other characteristics. Tremol is not only an important attribute of vocal art, but also extremely important in instrument performance. The acoustic essence of vibrato is the modulation of the fundamental parameters of sound. In the 1960s, Soviet research included vibrato in its research program, and subsequent studies further explored the frequency modulation amplitude coefficient of vibrato. It was found that the vibrato frequency of professional singers is about 5-7 hertz, which is consistent with international research results.

2、 Research Practice Objectives and Tasks

This chapter aims to obtain the perfection index of world vocal masters' vibrato through computer-aided research, in order to improve computer programs, judge the vocal talent of young singers, and deeply understand the origin and physiological mechanism of vibrato. The study used a program developed by the technical team of the Russian Academy of Sciences to analyze the vibrato features in singing and instrumental sounds, including pitch, fluctuation frequency, and frequency depth. The research subjects include 55 world-class vocal masters, including Xia Riabin. 1-3 notes were extracted from their 296 voice samples for analysis, of which Xia Riabin's voice samples accounted for 2/3 of the total research.

3、 Actual measured parameters and research results

The chapter on measured parameters and research results provides a detailed analysis of the vibrato data of Xia Riabin and other vocal art masters. Table 1 shows the main acoustic parameters of vibrato for masters of different voice types, including average pitch, vibrato frequency, fluctuation difference, frequency modulation depth, frequency modulation difference, half cycle number, and the phase relationship between amplitude modulation and frequency modulation. Xia Riabin's vibrato frequency is higher than the average level of the male voice, and its vibrato fluctuation difference is small. The frequency modulation depth is shallow, and the frequency modulation difference is slightly higher, showing the natural, perfect, and stable characteristics of her vibrato. The phase relationship of vibrato is mainly in the same phase in the male voice, in the opposite phase in the female voice, while Xia Riabin shows a slight opposite phase relationship. The example image of sound detection shows the measurement results of vibrato parameters of Xia Riabin and other singers, including waveform diagrams, amplitude envelopes, pitch variation diagrams, etc. The formation mechanism of vibrato involves the joint resonance of vocal organs such as the throat, pharynx, tongue, chin, and lips, as well as the involvement of respiratory organs such as the smooth muscles of the trachea and bronchi and the diaphragm. The phase relationship of vibrato may be related to the activity rhythm and coordination of the vocal parts. The study also discovered a rare phenomenon of "phase to phase" vibrato. Future research can further explore the mechanism of phase relationship formation in vibrato using methods such as X-ray fluoroscopy and plethysmography.

4、 Conclusion

The team from the Institute of Psychology of the Russian Academy of Sciences has developed a method and computer program for detecting vocal vibrato, analyzing the vibrato data of 294 vocal masters and revealing the acoustic characteristics of vibrato in different vocal parts. Research has found significant differences in the vibrato parameters of Charyabin compared to other male voices, and the phase relationship between vibrato AM and FM is the first study in the history of Russian vocal technology. Good vibrato techniques can enhance the leap, penetration, noise resistance, and clarity of sound, while inverse vibrato has higher aesthetic quality. The research results have been stored in a database for improving vocal talent detection programs and scientific research practices.