In my Bangkok days I used to teach Pali occasionally, and when it came to the niggahīta the first thing I would tell my students was to disregard the common description of it as a “pure nasal consonant”.
Instead, depending on what comes after it, one should think of the niggahīta character as either, (1) a nasal cypher (or placeholder) that may represent any of the five vagga nasals, or (2) a diacritic that converts the vowel preceding it (always a, i or u) into a nasalized vowel.
The cypher or placeholder usage has already been touched upon by Ayya Suvira. It applies in those cases where a niggahīta is followed by one of the twenty non-nasal vagga consonants. It’s an orthographic convention in certain Asian scripts that instead of writing ṅ, ñ, ṇ, n or m, one represents each of these sounds by a niggahīta and leaves it to the reader to give the consonant its appropriate value based on what comes after it, e.g., pronouncing saṃgha as saṅgha, saṃcarati as sañcarati, saṃphusati as samphusati, etc.
As for the nasalizing diacritic usage, this applies where the niggahīta either comes at the end of a word or where it is followed by an avagga consonant like v or s.
And what does a nasalized / niggahīta-ized vowel sound like? Just watch the French language video below; all of the sounds highlighted in it are niggahīta-ized vowels.
Unfortunately they’re not for our purpose the right vowels. The French nasalized vowels are /ɛ̃/, /œ̃/,/ɔ̃/ and /ɑ̃/, but what we need for Pali are /ã/, /ĩ/ and /ũ/.
So, this morning I paid a short visit to Phoible, the internet’s most comprehensive phonetics inventory site, in search of some living language that uses Pali’s three nasalised vowels.
The first language I could find with aṃ, iṃ and uṃ in it was Mina, a language of the Volta-Congo family spoken by about 330,000 people in the southeast of Togo.
Then on YouTube I found a young Togalese man called Delali Idrissou, who’s uploaded three videos showing (though I doubt this was his intention) Pali-using Buddhists how the three niggahīta-ized vowels should sound:
I’d like to end this post with a quick plug for the Phoible site mentioned above…
For anyone with even a slight interest in phonetics, a visit to Phoible is definitely something to place on their “Things to Do before I Die” list. To date Phoible’s contributing phoneticians have succeeded in documenting a total of 2,029 consonants, 1,094 vowels and 60 tones from languages all around the world. On this page you will find all these sounds listed in descending order of frequency. If you click on the IPA symbol for any sound you’ll be presented with both a full phonetic description of it and a list of all the languages in which it’s been found.
I’ll conclude with some fascinating phonetic factoids:
• Commonest consonant in the world: /m/, labial nasal sonorant, found in 96% of the world’s languages.
• Commonest monophthong: /i/, 92%.
• Commonest diphthong: /ai/, 3%.
• Rarest consonant: /ʃ̞ʼ/, lowered palato-alveolar ejective fricative, found in Jibbali, a Semitic language spoken by a small mountain tribe in Oman.
• Rarest monophthong: /ɵ̆/, found in Standard Tatar.
• Rarest diphthong: /uœ/, found in the Southern Yukaghir language of Arctic Siberia.