Sonority may not sound like much, other than a group of girls similar to a fraternity, but it is incredibly important for the way we speak. In fact, if you re-read this paragraph, you will find a striking pattern based on sonority. This is because the amount of 'noise', or sonority, that each sound has determines where it is placed in a syllable. This is known as the sonority hierarchy, which ranks each possible phoneme of a language by the amount of 'noise' it makes. We therefore end up with one sonority peak in the middle of a syllable, which is usually a vowel. Surrounding the sonority peak is a slow increase in sonority. In other words, each syllable starts and ends with the quietest phonemes and we get a pattern of "quiet >> loud >> quiet". If we take the word 'dog' for example, we can clearly see that the 'd' and 'g' are quieter than the sonority peak, in this case, the 'o' vowel. In words longer than one syllable, such as 'paragraph' we have a pattern of "quiet >> loud" across the first two syllables, with the final syllable having "quiet >> loud >> quiet": pa . ra . graph.
The first syllable of paragraph uses the exact same type of phonemes as we saw in dog, a 'p', which is one of the least sonorant sounds in English, followed by one of the loudest: a vowel. The second syllable uses 'r', which falls in between a 'p' and a vowel on the sonority hierarchy. The final syllable shows a slower incline in sonority as we have an intermediate consonant, 'r', before we get to the vowel. This syllable then ends with 'ph', or an 'f'' sound, which is again lower in sonority than a vowel! If you're wondering why, then the reason is just because English syllables are constrained to using sounds in this order. We cannot have a word that doesn't follow this pattern.