The function expansion of iconology has become an important event in humanities research in the middle and late 20th century, and its influence cannot be ignored. MitchellW, J and T, an American image theorist, said: "This is another major turn in the humanities after the linguistic turn, which has brought a huge paradigm shift to the study of humanities and social sciences." [1] In the past few decades, iconology has continuously expanded its research scope and closely combined with other disciplines, which has made important contributions to promoting the research of humanities and brought new opportunities for the development of music disciplines. Music iconology is an effective combination of iconology and musicology. Various branches of music discipline gradually began to pay attention to the important role played by images in their research, and constantly excavated images related to this discipline, thus exploring new musical cultural events. Therefore, musical images have high theoretical research value for many musicology subjects. As Professor Qin Luo said: "Because of the' non-musical' characteristics of video materials, it is indispensable and irreplaceable to study the cultural dimension and its significance in visual arts." [2] However, images are not only of theoretical significance to vocal performance at the research level, but also of practical value to the diversified exploration and expansion of vocal art teaching forms in colleges and universities.

First, the value of image analysis

The singing image in music image can be divided into two aspects: material image and implicit image. The characteristics of material image are concreteness and traceability. Implicit image mainly refers to the inner spiritual essence attached to material image. In the music video media, the two are interdependent, mutually existing, and relatively independent, performing their respective duties. In other words, the dual-level characteristics of music image provide a "static" medium for vocal music teaching objects to analyze internal and external images. On the one hand, we can locate and analyze its external characteristics such as singing posture, costumes, expressions and movements, on the other hand, we can deeply explore the hidden images of the singer's inner feelings, spirit, culture and aesthetics.

1, the resolution value of the material image. Compared with audio-visual products, music images are not audible, but they have a more powerful function of capturing actual music performance pictures. Especially from the perspective of modern image recording and storage technology, the fineness and fidelity brought by the high "pixel point" of the image can truly and accurately locate every detail of vocal performance. Make up for the shortcomings caused by the fluidity, inappropriateness and fleeting image of audio-visual and live performances. Therefore, in vocal music teaching, the use of musical images can make the teaching content more intuitive, detailed and localized. The extension of image helps students to capture the externalized form of singing, so as to seek the improvement of inner emotion. Especially at this moment, using computer technology and camera capture function, through computers, projectors and other equipment for specific positioning analysis. Every movement, vocal state, expression, etc. It has become a useful reference medium for teachers' teaching, students' self-study and imitation.

2. The analytical value of spiritual images. Image is not only a mirror copy of things, but also an abstract summary of spirit and soul. Aristotle first put forward the concept of spiritual image, which he thought was "the external expression of the soul and the image of the spirit." [1] Therefore, the positioning and analysis of the image of vocal music performance should not only stay on the external imitation, but also analyze its internal "soul" (such as spiritual soul and artistic soul). In the teaching process, while fully affirming the spiritual image positioning and analytical value of vocal music performance image, we should also understand the difficulty of its analysis and arrange teaching methods in advance. Especially through the external image to try to figure out the singer's inner mood, emotion, singing state and so on. For example, analyze the singing mouth shape to find the sound position, imitate the singing action and feel the inner feelings. All these require teachers to give students directional guidance in teaching and help them learn the spiritual soul in the image of vocal music performance step by step, so as to achieve the singing effect with both form and spirit.

Second, the value of historical reproduction.

Music images not only have the function of capturing pictures with modern cameras and electronic technology, but also can reproduce the history of vocal music culture through images preserved in the historical process. Because, in that era when there was no sound, photo and image recording, graphic arts such as painting and statue made up for the regret of recording "being present", which made some vocal performance knowledge that was only learned from books and never recorded in words appear in front of modern people, providing a cultural feast of "being present". These images are the products of a specific historical period, which not only help college students to understand the performance forms and singing characteristics of vocal music in the past, but also can see the artistic value and cultural connotation of vocal music through the images. For example, The Riverside Scene at Qingming Festival shows the performance scene of the rap art of Washe Goulan in the Northern Song Dynasty, which provides us with specific reference materials to understand the prosperity of the rap art performance in the Song Dynasty, thus deepening people's understanding of the emergence of the Song Zaju and its relationship with the rap art. The musical image reproduces a large number of historical pictures for us and creates a rare "sense of existence" for our research. This also includes learning and exploring the singing and life of vocal artists. For example, WalterSalmen discussed in his article "Musical Images of Towns and Villagers in the 14 to 16 century" that as early as the 13 century, western vocal music began to develop, and some minstrels and business singers who were outside the court and theocracy became the beautiful scenery of western singing art in this period. But only through simple narration can we understand the life and singing situation of the singer at that time. It was people who discovered the carvings on the ancient buildings left over at that time, which provided us with an opportunity to study the vocal music art of this period [2]. "These musical images convey a fable and the scene of a musical activity that the bard in northern France once showed off." It can be seen that the video materials not only provide a medium for us to deeply understand the development of vocal music art in the historical context, but also provide a valuable basis for students to deeply understand and learn the life, status, music practice and performance life of vocal music performers, so that learners can intuitively understand the living conditions of vocal music performers.

Third, situations create value.

Vocal music art is a comprehensive performance form. In addition to mastering singing skills, learners should also integrate the inner feelings of songs with singing skills and action expression and express them through physical media. Among them, creating situations can be regarded as an effective measure to cultivate students' comprehensive performance ability. Images can play the role of "creating virtual situations" and solve the problem of making up for the lack of comprehensive practice opportunities for college students [3]. In the past, in the process of vocal music teaching in colleges and universities, the role of teachers was the leader, mainly guiding students to learn related singing skills through language narration and singing demonstration, and rarely spending too much time on comprehensive training such as emotional expression and physical performance. However, vocal music singing is a comprehensive art of expression, especially when singing large-scale works, the combination of emotional expression with singing skills, physical expression, facial expressions and other issues has become the key to good or bad singing. Under the above conditions, music image can give full play to its advantages of creating virtual singing situations and providing students with comprehensive practical opportunities. In the meantime, you can create a situation with the help of projectors and stereos, simple costume props and images. Teachers only need to stage package the traditional concert singing form in the multimedia classroom. Students enter the role of aria and create specific opera scenes through musical images. Teachers guide students to quickly integrate into the situation in the set stories, and integrate emotional expression, body movements and facial expressions into the process of student role interaction for singing training.

Fourth, the main incentive value

The core idea advocated by music education is "student-centered", so is vocal music education, that is, all teaching contents, teaching methods and teaching forms are carried out around students. In the traditional vocal music teaching in colleges and universities, it is difficult to change the one-way knowledge dissemination mode led by teachers. However, the application of musical images in vocal music teaching is not only of practical value for analyzing artistic images, learning vocal music history and culture, and creating virtual performance situations. In this process, students' subjectivity can also be fully stimulated and mobilized. 1, guiding the subject to explore. The presentation of images provides a medium for students to explore actively. When we face the image, culture and connotation in these pictures, paintings and sculptures and interpret the differences in themes, we will get different feelings. College students, in particular, are physically and psychologically mature, and have certain ability of evaluation and discrimination. Moreover, man is the subject with personal perception ability. They have their own knowledge reserve, appreciation experience and musical accomplishment, and will also present diversified exploration scenes in the process of analyzing images. There is no such thing as a "standard answer" or a "unified model". Therefore, students can give full play to their subjective initiative and cultivate their ability to explore actively in the process of analyzing the image of music and the emotional symbols in the image. 2. Stimulate the interest of the subject. Interest is the motivation for students to learn music knowledge. In the process of vocal music learning, we should pay attention to changing the current educational status of "technical" learning and use various means to stimulate students' interest in learning. In the process of teaching with musical images, teachers can not only guide students to analyze other people's vocal performance fragments, but also evaluate students' own performance pictures [4]. Especially when music pictures are set to students themselves or their familiar classmates, it can not only concentrate students' attention well, but also guide students to actively find and solve problems and stimulate students' interest in learning.

Verb (abbreviation of verb) conclusion

The application of music image in vocal music teaching in colleges and universities has important application value, but we should also pay attention to the problems that are easy to appear. Especially in the modern society with superb picture processing technology, on the one hand, teachers should learn to distinguish authenticity and try to use original and non-forged music historical pictures for teaching. On the other hand, "in the era of virtual reality and computer simulation, the generation of images is more the product of careful combination, design and arrangement." This selected product is not universal and representative. " [5] Therefore, teachers should avoid choosing images that are carefully processed by technology and lead to distortion of vocal performance for guidance.

References:

[1] Lu Tao, ideology of image text-three key words in iconology research [J], Inner Mongolia Social Sciences, 2013,34 (4)

[2] Qin Luo, the cultural dimension of visual sound in visual art and its significance-uniqueness and irreplaceability of music iconology [J], Music Art, 20 12(4)

[3] Liu Yuan, the new century-oriented vocal music teaching mode in normal universities [J], China Music, 2007(3)

[4] Chen Hongru, Reflections on Vocal Music Teaching Reform in Normal Universities [J], Journal of Nanjing Art Institute, 2006( 1)

[5] Duan Gang, the manipulation of image symbols by ideology [J], Hebei Academic Journal, 2007,27 (6)

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