Man pages matching name voice_set_pan in section 3alleg4:

voice_set_pan.3alleg4.en	debian 10 / allegro4-doc
voice_set_pan.3alleg4.en	debian 11 / allegro4-doc
voice_set_pan.3alleg4.en	debian 12 / allegro4-doc
voice_set_pan.3alleg4.en	debian 13 / allegro4-doc