He whispered throatily, "I'll miss you," his voice deep with emotion.

throatily 是由名词 throat（喉咙）加上后缀 -ily 构成的副词形式。throat 指"喉咙"，-ily 是常见的形容词变副词的词尾。throatily 形容声音像是从喉咙深处发出的，带有沙哑、低沉的特质，通常用来描述充满感情或性感的声音。