Ca Tru appeared in the early 16th century. Overcoming the ups and downs of history, it was believed to be impossible to survive. However, until now, with its unique characteristics, Ca Tru has played an important role in Vietnam as well as worldwide. It is inscribed on the list of Intangible Cultural Heritage of Humanity by UNESCO.
Ca Tru has many different names. In each region, depending on time, it was called "hat a dao", "hat co dau", "hat nha to", etc. However, with its many names, Ca Tru has been always attached with Dao Nuong (Ca Tru female singers). It is not easy to become Dao Nuong because they must meet rigorous conditions such as voice, musical ability, knowledge of music and poetry, passion and patience. The existence of Ca Tru depends on Dao Nuong because they are singers conveying and showing its beauty and uniqueness as well as helping it exist until now.
Ca Tru is organized into guilds managed by leaders and vice leaders. There are rules of professional teaching and ways of playing music and singing. There are also customs to determine whether Dao Nuong is qualified like Mo Xiem Ao ceremony (ceremony of opening clothes) referring that the learner is allowed to wear clothes of Dao Nuong to debut at village temple). There are also rules of choosing Dao Nuong for singing contest (including talent, countenance, and virtues). Singing contests and giving prizes are organized explicitly and festivals are celebrated very seriously. Ca Tru was originated from folk music and some of folk shows and dances. At the beginning of time, it was a synthetic art including music, poetry, dance, and shows. Therefore, its uniqueness is the diverse and sophisticated combination of poetry, music and even dance.
Most forms of Vietnamese traditional music are a combination of poetry and music, such as Ve, Dong Dao, Lullaby, Ho, Ly, and Cheo. Ca Tru is also a genre of chamber music like ca Hue (Hue singing in Central Vietnam) and Ca Tai Tu (amateur music) in South Vietnam. The rhythm of Ca Tru is not fixed but depends on the cadence of verse, so songs like Gui Thu (Sending letters), Hat Ru (Lullaby), Bac Phan, Muou (beginning or ending part of hat noi), etc have different rhythms.
Especially in Ca Tru, vocal and instrumental music are parallel to each other and each genre has specific characteristics. For vocal music, apart from Tuong, nothing has diverse and unique techniques like Ca Tru. It expresses the clearest when Dao Nuong sings. Singing techniques are very highly polished. It is not necessary to open widely the mouth, push the air from the lungs but hush up the air in the throat. Only with those, the voices, as well as the lyrics, are still clear.
Besides vocal music, instrumental music is very important in Ca Tru. It includes Co Phach, Dan Day, and Trong Chau.
* Co Phach
Co Phach is a piece of bamboo or wood called Ban Phach and two wooden sticks: one is a large Phach and another is a tiny Phach. Two wooden sticks knock Co Phach, which makes a high and low or strong and weak sound. The performers use large phach and tiny phach very smoothly. Their hands move up or down flexibly like dancing.
* Dan day
One of the most important musical instruments in Ca Tru is dan day (a Vietnamese plucked lute). It has a trapezoidal or rectangular wooden body. It has surfaced but not the bottom and is made from sycamore. Its neck is very long with ten or eleven raised bamboo frets. It also has 3 silk strings which have different ways of pressing, which makes its rhythms win the hearts of the audiences
. * Trong Chau
Besides, Trong Chau (a type of Vietnamese traditional drum) also contributes to the uniqueness of Ca Tru. Its size and way of playing in ca tru is different from in Tuong. The drumstick is not called Dui But Roi Chau. Roi Chau is made from wood and longer than drumstick of Trong Khach. The drummer who is good at Ca Tru and understands laws of music profoundly just can handle Roi Chau. The sound of Trong Chau makes the voice and verse become outstanding. All of three musical instruments make the songs of Ca Tru become diverse with many timbres, functions and have positive changes continuously. Ca Tru of Vietnam reveals the seduction, elegance, and uniqueness. Its distinct characteristics have created the differences which any kind of art does not have.