Although the type of flute cannot be indentified, it could be a transverse flute or an end-blown flute such as Shakuhachi bamboo flute which can shift the scale by using several holes on it because the certificate refers to a music scale.
笛の種類は特定できないが、音階があることから、複数の穴を配して音階を変えることの出来る横笛か、尺八のような縦笛であったのだろう。