:Sonority hierarchy:

Pronunciation GB: səˈnɒrəti, GA: səˈnɑrət̬i

A ranking of sound types depending on their their sonority, which is usually defined as the degree of resistance of an articulation to free airflow through the vocal tract, where higher resistance equals lower sonority. There are a number of versions of the hierarchy to be found in the the literature. One common one is:

obstruents<nasal stops<liquids<glides<vowels

where < means "less sonorous than". The hierarchy is used define universal tendencies in syllable structure. Syllables tend to increase in sonority towards the centre and then decrease towards the end.