Hóuyīn (-)
original: 喉音
embellishment of a tone or melody, mentioned by name, but of an unidentified nature
Literal translation: 喉: "larynx / throat"; 音: "sound / tone"; A playing technique, mentioned, among other techniques, by Wong, who unfortunately fails to add a more specific description.
Wong, Samuel Shengmiao: Qi’ - An instrumental guide to the Chinese orchestra. Singapore, 2005, p.139.
汉英词典 (Hàn Yīng cídiǎn) / A Chinese-English dictionary. 北京 [Běijīng], 1985, p.280 & 826.