"Very loudly" is grammatically correct, but it's often considered redundant.
* "Loudly" already implies a high volume. So, using "very" in front of it can be unnecessary and even sound awkward.
* "Loud" is an adjective, while "loudly" is an adverb. Using "very" before an adverb can sound a bit clunky.
Here are some examples:
* Instead of "He spoke very loudly," you could say "He spoke loudly."
* Instead of "The music was playing very loudly," you could say "The music was playing loudly."
However, there are some cases where "very loudly" might be appropriate:
* For emphasis or to highlight an extreme level of volume. For example, "The crowd cheered very loudly for the winning team."
* When comparing different levels of loudness. For example, "She spoke very loudly, much louder than she usually does."
Ultimately, the best way to decide whether to use "very loudly" is to consider the context and the desired effect.