Does Tibetan have nasalized consonants, or is the nasalness on the vowels?

Question

I am working with a native Tibetan speaker to translate some words from Tibetan into English, and I noticed they were marking the pronunciation of certain consonants with a nasal marker.

They marked it on the consonant though, for example:

Form	Transcription	Word Class	Meaning
གཏམ	tam̃	noun	conversation
གཏལ	ʈal̃		(meaningless syllable by itself)
གནག	nag̃	noun	cattle
གནང	naŋ̃	verb	give
གནན	neñ	verb	press
གནམ	nam̃	noun	sky
གནུབས	nub̃
གཡབས	yab̃	verb	to have sex (past participle)
གཡར	yar̃	verb	to lend (r = trilled or flapped r)

These are just a few.

They created a recording here of nasalised and non-nasalised /n/, for the meaningless syllable བསྙོན་ nyoñ vs ཉོན་ nyon ‘listen (command)’.

Is this actually on the /o/ sound (for nyon), that is, are these "nasalities" actually on the preceding vowel? Or are they actually on the consonant? How should they be represented? Wikipedia says nasalized consonants are rare, and then this is /n m ŋ/, which are already nasalized! Can you have a nasalized nasal? Or should we be saying the nasalness is on the preceding vowel?

It seems maybe because of Tibetan orthography this translator might be imagining the nasalness is on the consonant (when it is really on the vowel)? They marked the consonant as having nasalness without any prompting from me, so I'm not sure if that's what they meant or if it's a tradition/orthography sort of thing.

I will note that in some cases, they did mark the vowel with nasalness, when it didn't have a trailing consonant (we have only covered single syllables so far):

Form	Transcription	Word Class	Meaning
བསླད	lẽ	verb	deceive
མངའ	ŋã	verb	possess

Answer 1

I'm going to go out on a bit of a limb, and say that the reference to 'nasal and non-nasal consonant' is actually high and low tone respectively, as found in Standard Tibetan, both in Lhasa and in the greater Tibetan diaspora (most of whom are speakers of Ü-Tsang དབུས་གཙང Wylie: dbus gtsang).

Tibetan spelling reflects the phonology of Classical Tibetan of the 11th-12th centuries CE, and is full of consonant clusters. Through the later mediaeval period, Ü-Tsang and Kham Tibetan went through a similar process of initial consonant devoicing as Chinese, Thai, Lao and Vietnamese, undergoing tonogenesis whilst drastically simplifying the clusters. Amdo Tibetan avoided tonogenesis, and underwent more limited consonant cluster simplification.

The way that this panned out for Lhasa Tibetan was that 'true' initial nasal consonants (ང ng, ཉ ny, ན n, མ m) and voiced obstruent consonants (ག g, ཇ j, ད d, བ b, ཛ dz, ཞ zh, ཟ z, འ ', ཡ y, ར r, ལ l), ended up with low tones. However, in many consonant clusters, the syllables ended up with high tones in general (there is some nuance here with the specifics though!).

Looking at the list of data above, all of the first chart start with a historical obstruent ག g- in a cluster (gt-, gn-, g.y-), which would lead to high tone on all their syllables. The 'minimal pair' example between nonsensical བསྙོན bsnyon and ཉོན nyon has a very clear tonal difference, and with the Wylie transliteration you can see the difference in consonant clusters.

The use of the tilde over the vowel seems to be the same: བསླད bslad and མངའ mnga' (yes, two nasal consonants m and ng that would be low tone if alone) both start with historical consonant clusters, and have high tones in Standard Tibetan.

Answer 2

The main point that needs to be made is that Tibetan is a language family, although there is also a single written languages called (in English) Tibetan. As for the specific language that you are working on, only you are in a position to answer that question. It is, however, probable, that there are contrastively nasal vowels. It is also very probable that sorting out the relationship between written Tibetan and actual speech is going to be a complex adventure.

Based just on the recordings, it looks like there is a contrast between oral and nasal vowels between nasal consonants. [n, ŋ, ɲ] are, of course, nasal consonants so Tibetan does has nasal consonants. "Nasalized" is often applied to nasal consonants that are not normally nasal, for example [l̃]. Based on Nornang's Lhasa dialect, my main hypothesis would be that there is no phonemic "secondary" nasalization on sonorants, instead vowels are contrastively nasalized. Since the language originally had a lot of consonants which were deleted but are still preserved in writing, I would also expect speakers to think in terms of nasalization as being related to consonants given that is not they are spelled. However, there is some indication in the Lhasa dialect that nasal vowels are still treated as VN sequences, which is that intervocalic lenition of the lingual consonants between vowels does not happen after nasal vowels.