also: とういん
The tō-on reading of 行 in 行灯 is 'an'.
Tō-on are character readings based on Chinese pronunciations from the Song dynasty onward.
Standard kanji form for this linguistic term.
Alternate reading; とうおん is more common.
唐音 names a category of Sino-Japanese readings introduced chiefly from Song China onward. Here 唐 is used in the broad historical sense of China, not as a precise reference to the Tang dynasty.