Is a syllable defined phonetically or etymologically?

Question

Reading recent postings about syllables I've been struck and baffled by talk of the possibility that words may have a different number of syllables when they are written than when they are spoken.

Is "church" one syllable or two?

How many syllables are in the word 'hour'?

As a musician I am very clear that a book of music is just that, a book containing a (more or less helpful) representation of music. The book itself is not a piece of music (any more than Magritte's painting of a pipe 'is' actually a pipe). Only the sound of music is music. It is also my view (and among musicians I'm not out on any kind of limb!) that wonderful and awe-inspiring as music theory is to me, it is based on the work of a succession of rule-breaking composers. Music theory has always, and can only, play catch-up with music practice.

Do you think this is the case with language ? When I say church I make two clear sounds. I think you have to. On what grounds could church be said to have only one syllable ?

The OED offers that syllable is

a vocal sound or set of sounds uttered with a single effort of articulation and forming a word or an element of a word; each of the elements of spoken language comprising a sound of greater sonority (vowel or vowel-equivalent) with or without one or more sounds of less sonority (consonants or consonant-equivalents).

If I say, "I'll meet you at the church" - church involves, for me, two 'efforts of articulation' ... two syllables?

Answer 1

Not all English speakers pronounce all words with the same number of syllables.
However there are general agreements as to how many syllables any word has. This is certainly true in singing.

In traditional music, one syllable will be sung on one note. Of course, if there are more syllables than notes, one "cheats" and adds notes. More notes than syllables, then one can "cheat: by distorting the word to created new syllables. Many songs have an even syllable to note equation. The "cheating" usually happens when there is an attempt to fit too many or too few words to an established tune,
In the well known song "Mary Had a Little Lamb", there are exactly the same number of syllables as notes in the tune. I have never noted any problems with this song as to syllabification.
Often persons who are not native speakers of English and speak English with an "accent" exhibit no such "accent" when singing English songs. Native and non-native speakers follow the same syllables with the same stress dictated by the tune. If one wished to assure the convention as to number of syllables is followed, one could do worse than to practice singing single syllable words on a single note

Almost always, the number of syllables in an English word is determined by the number of sounds (vowels) in the word; not the number of written vowels, but the number of distinct vowel sounds.

lit-tle

The second vowel in "little" is not written. Tl could not be pronounced without the understood vowel.
Etymology would have little to do with syllabification, unless one were trying to pronounce a current English word in the manner of some previous era. That does not occur very often.
I'm not sure this is a very serious issue for the most part. Probably few care if a syllable is added or subtracted in speaking as long as the meaning of the word is clear. Unless one is singing.

Answer 2

Syllables are only related to speaking. A syllable is determined by a vowel pronunciation. In the U.S., secretary is a four syllable word. In the U.K., it is usually only three syllables. Writing does not determine syllables. One's pronunciation or the pronunciation indicators in a dictionay determine syllables. As to "hour", it is a diphthong in southern U.S. (two vowel sounds gliding together in one syllable), but is two distinct syllables in the U.S. North, like ow-wer". Same goes for fire and oil. Church is very clearly one syllable, since it has only one vowel pronounced, unless you know of a locale where it is pronounced "chur-chah".

Sounds made without any vowel, such as "Whewww!" for relief of danger, are not words and have no vowel sounds. Shouting "Arghh" like a pirate could be considered a word with one syllable.

Words in a song are not nearly as exact as one might think. "A-may-zee-ing-grace" is sung as five distinct tones, but if one spoke this phrase in conversation, it would be only four syllables. In "Angels We Have Heard on High", the word "Gloria" is sung with many syllables or tones. Spoken, it is only three... unless a dialect pronounces it as "glor-yah". Then the second syllable is a diphthong. Many languages have diphthongs. In Mandarin Chinese, there are dozens, such as "tian" for sky / heaven / day or "guo" for a melon-like fruit. If you pronounced tian as two syllables like "tee-ann", most Chinese would not understand you. Same for guo pronounced like "Goo-wah".