All the Japanese arts were somewhat mistreated after Japan's 19th-century collision with the West. Temples, shrines, pagodas were threatened with destruction, and the classical noh drama all but vanished. Worst hit was hogaku, Japanese traditional music. In the pathologies that followed Japan's chase after Western ways, native music was neglected and then, to an extent, suppressed.
Hogaku was denied any place in the Japanese educational syllabus. It has been only quite recently (in 2002) that it was finally included into the basic curricula of Japanese public-school music education. The century and a half of relative silence, however, meant that much was lost.
One of the people concerned about this loss was the acoustician Ichiro Nakayama who realized that traditional vocal techniques were being forgotten and that the links between the Japanese language and song were now very few. He consequently began what became a lifelong study — finding out how the Japanese language is actually sung by the traditional singers still here.