wǔ yīn
five notes of pentatonic scale, roughly do, re, mi, sol, la
five classes of initial consonants of Chinese phonetics, namely: 喉音[hou2 yin1], 牙音[ya2 yin1], 舌音[she2 yin1], 齒音|齿音[chi3 yin1], 唇音[chun2 yin1]
wǔ yīn bù quán
tone deaf
unable to sing in tune