Namkung, Ju. Phonological Inventories of Tibeto-Burman Languages. 1996. hh:hld:Namkung:Tibeto-Burman
"Only nasal and glide initials occur in both tones. Voiceless affricates and fricatives have voiced allophones in low tone (except /ɕ/, whose low tone allophone has devoiced)."