Tolkien describe various rules in which nasals [m], [n], [ŋ] became their homorganic voiceless stops [p], [t], [k]. Combined together, his examples include all possible combinations of nasals and a following voiceless stop, aspirate or [s]. This is all the surviving primitive voiceless consonants except for [x].

The m-combinations given by Tolkien are MP, MPh (SD/420) and MT, MTh, MK, MKh, MS (SD/421) which is a complete list all possible combinations. The n-combinations given are NT, NTh (SD/420) and NS (SD/421), which are all the possible combinations after [n] assimilated in position to following consonants. The ŋ-combinations were not given directly by Tolkien, but he did describe the development of NK, NKh, both of which would have become [ŋk], [ŋkʰ]. These are the only way in which [ŋ] could appear before a voiceless stop or aspirate ([ŋ] could not appear before [s]).

This change happened around the same time as [ŋx] became [xx]. Since the change in [ŋx] was probably early, these other nasal changes were likely early as well. This change seems to have had a lasting influence, however, remaining functional in most cases with the later assimilation rules of Classical Adûnaic.

For the remaining primitive voiceless consonant ✶[x], the combination [ŋx] became [xx], as noted above. The combinations [mx] and [nx] developed into [mh] and [nh] when spirant [x] became breath [h] except before [s] and for double [xx]. The final result written as “mh” and “nh” but pronounced as a voiceless double [m̥m̥] and [n̥n̥] “with breath off-glide” (SD/421).