sonorous

The highlight of the hike was the sonorous cave, which produced a ringing echo from the hiker’s shouts.

For this reason the Italian opera seldom sinks into a poorness of language, but, amidst all the meanness and familiarity of the thoughts, has something beautiful and sonorous in the expression.

Vowels are more sonorous (acoustically powerful) than consonants, and so we perceive them as louder and lasting longer.