The topic of nasality has come up on the Facebook page of Pronunciation Best Practice. A question asked there by Daniel Schulte made me check on what Wikipedia has to say on the topic, and this has raised some other issues concerning the WP material.
Here's the original question:
I've got a question about nasality (not only the m n ing sounds)
as far as I know: The air from the lung can flow through your mouth and nose ok. when the air flows a lot through your nose the voice sounds nasal. but why does a blocked nose (a cold or pressing the nose together with your fingers) lead to a nasal voice when its actually causing that the air is only flowing through your mouth?
also: is the fact that some accents (standard general american compared to standard southern british, or portuguese compared to spanish) sound more nasal, a direct consequence of the exact tongue/lips/jaw configuration within the vowel chart or is that a separate, independent aspect? thanks.
The first response posted to this question was from Anthony Lauder:
Before you can release air through your nose you have to first build up air pressure in the nose. The more "blocked" the nose, the more pressure you can build, and the more "nasal" the sound will be. When you have a cold, then, it blocks the nose and helps create that air pressure leading to nasal sounds.
This was followed by a contribution from Petr Roesel.
When you block your nose, the velum usually hangs down, i.e. the nose as a resonator is added to the oral cavity. This enhances certain frequency bands, which cause the impression of nasality
The comment I added to this Facebook discussion was this:
In answer to Daniel Schulte, it's a fallacy that a blocked nose leads to a "nasal voice". Read the Wikipedia article on Nasalization, and note "Denasalization". See also the WP article on Hypernasal speech. If American or Portuguese speech sounds more nasalised, that must be because the speech contains more nasalised vowels (phonemes or allophones) than the accents you are comparing them with. Nothing to do with tongue/lips/jaw configurations. In answer to Anthony Lauder, I'm afraid you've got it completely wrong. It's nothing to do with pressure, and if anything the more blocked the nose is, the LESS nasalised the sound will be. And Petr Roesel, please can you tell me where you got the evidence that the velum is lowered when the nose is blocked?
So far, nobody else has joined in the discussion. Since I recommended reading relevant bits of Wikipedia on the subject, I thought I ought to check on what there is. There's a good article on Nasal vowel and another on Nasal consonant (though editors have flagged problems with references in this latter article). In addition there is an article on Nasalization, which contains quite a lot of information relevant to the question, and contains a brief section on Denasalization, with a link to a separate article on this topic. The article on Denasalization contains a few questionable points. It states "When one speaks with a cold, the nasal passages still function as a resonant cavity so a denasalized nasal [m͊] does not sound like a voiced oral stop [b], and a denasalized vowel [a͊] does not sound like an oral vowel [a]." It seems to me that the nasal passages are only likely to function as a resonant cavity if the soft palate (velum) is lowered, as would be the case in the two examples given. When the soft palate is raised, it seems to me that the nasal cavity must be effectively sealed off from the vocal tract, hence my query to Petr Roesel.
The other worrying thing in the Denasalization article is the statement that "[Denasalization] ... occurs when the sinuses are blocked from a common cold, when it is called a nasal voice". The article adds the caution that this "is not a linguistic term". It turns out there is a Wikipedia article on Nasal voice, and I must say I don't feel very happy about it from the phonetic point of view. The lead section says "A nasal voice is a type of speaking voice characterized by speech with a 'nasal' quality", and a comment has been added on the Talk page of this article, correctly pointing out that this "definition" is "self-referential and therefore not helpful". A WP editor has added a [clarification needed] note. The lead continues "It can also occur naturally because of genetic variation.", which seems to me meaningless as it stands. The article then states that the term Nasal voice may be used to refer both to hyponasal and to hypernasal speech (i.e. speech with too little nasality or too much), thus referring to two opposite entities. This view would, if correct, support the implication in the original question by Daniel Schulte that a blocked nose (causing hyponasality) would lead to "nasal voice", but there seems little or no justification for using the term "nasal voice" in this way. The article's citations to justify the use of the term are two: one is a brief note in the website of an American speech therapy clinic, which talks about Nasal sounding voice and warns that "Nasal voice is an incorrect term as the voice itself is normal". The other citation is of a short section of a textbook called Basic Clinical Radiobiology , and the article seems to be largely based on this work. I need to do some more reading about this topic in the speech pathology literature, to see how widely used the term nasal voice is there, but my current feeling is that from the phonetic point of view the article is of doubtful value.