In both Sindarin and Noldorin, voiceless initial nasals were voiced, as noted by David Salo (GS/§4.84). Salo put this change fairly early, to coincide with the voicing of medial voiceless nasals that developed from mph, nth, nch; for simplicity I treat the medial and initial development separately. The initial voiceless nasals were mostly developed when initial [s] unvoiced following consonants: [sn-], [sm-] > [n̥-], [m̥-]. Tolkien wrote these as hn-, hm-. Examples include:

• ✶snagdē [> *hnaið] > S. naeð “wounding, wound” (PE19/91).
• ᴹ√SNUR [> ON. *hnorð] > N. nordh “cord” (Ety/SNUR).
• ᴹ✶smalinā > ON. malina > N. malen “yellow” (Ety/SMAL).
• ᴹ✶smaldā > ON. malda > N. (h)malt “yellow” (EtyAC/SMAL).

As indicated by the last example, in the 1930s Tolkien seems to have vacillated on this sound change, and voiceless initial nasals were frequently retained, as noted by David Salo (GS/§4.221). For example: N. hniof “noose, snare” (Ety/SNEW), N. hmael “stain; stained” (Ety/SMAG), N. hmâl “pollen, yellow powder” (Ety/SMAL). There is no evidence voiceless nasals ever survived in Sindarin.

Conceptual Developments: In Gnomish of the 1910s an initial sm- > f-, so this sound was probably never unvoiced. In the Early Noldorin of the 1920s, however, initial sm-, sn- > m-, n-, perhaps passing through a voiceless phase first. See the entry on how initial [s] unvoiced following consonants for further discussion.

See S. voiceless nasals were voiced for discussion.