Question: I'm looking for a fully accurate statement of an algorithm to count syllables in words. What I'm finding when I research is inconsistent or what I know to generate incorrect results. Does anyone have any suggestions of how to accomplish this? Thanks.

The algorithm I'm using now:

1. Count the number of vowels in the word.
2. Do not count double-vowels ("rain" has 2 vowels but is only 1 syllable)
3. If last letter in word is vowel do not count ("side" is 1 syllable)

Are there any more rules I'm missing? I'm trying to determine in testing for my incorrect results if the algorithm I'm using is wrong or my implementation of it.

Answer: 
> 
> I'm looking for a fully accurate statement of an algorithm to count
>  syllables in words
> 
> 
> 

There isn't one. Period. Whatever algorithm you invent, I promise to find a counterexample. In certain languages(Armenian and Russian come to mind) the algorithm is pretty straightforward - count the number of vowels. In other languages, such as German, it's not as straightforward but still doable. In English, I am afraid, the transduction between letters and sounds is absolutely irregular. 

For example, 

***coincidence***. ***oi*** is to be counted as two syllables. But in ***boil*** it's only one syllable.
Also, not counting the final vowel is not always accurate. Consider the name ***Penelope*** or ***Hermione***. Or ***banana***

Another curious case is when the syllable exists without a printed vowel. For example, ***table*** is a bisyllabic word but the second syllable is generated by the invisible sound between ***b*** and ***l***. Also, don't forget about words originated from greek, which can have a lot of consecutive vowels. E.g. ***onomatopoeia***. 

So, there is no accurate algorithm. The only way you can go is to try to find an algorithm which works in many (I am avoiding the word most) cases. But in this case you should redefine your requirements.
Old question, but still, people probably read it once in a while and it is an open question. 

Words aren't built up out of discrete, well defined, agreed syllables - you try your best to separate language into syllables, and the way you do it depends on the purpose - some are more phonetic, others rely more on spelling. 

Phonetic methods produce different results depending on the accent or dialect of the speaker, and/or how clearly each individual is speaking at a particular time. In some phonetic methods, syllables share sounds - i.e. the last sound in one syllable can be the first in the next, and this can cross word boundaries. 

What is taught in schools (if the school bothers at all) often is a mixture of spelling and phonetic rules designed to help children spell. They try to have a few memorable rules that work a lot of the time, they aren't meant to be 100% correct or exhaustive. 

With any particular method, you'll likely find things that don't sound right to you. 

Now the answer: For a readability metric, it won't matter much which method is used. Even just counting letters in the words (or vowels) can work also. If you are trying to match someone else's results, then you need to know their method.