Articles clarification

[ama3738]

1. Concorde can travel at twice the speed of - sound.
2.family needs to have an understanding of what the puppy needs.
3.It serves an excellent "California-Mediterranean" menu.

I want to know why the before speed and no article before sound in sentence 1

and why an before understanding in sentence 2

and why an before excellent menu in sentence 3

I want to know if menu, speed sound and understanding are countable or non countable nouns and what is the rules.
Thanks

[Gillnetter]

1. Concorde can travel at twice the speed of - sound.
The speed is a specific speed - article is required.
Sound is not specific - no article is required.
2.family needs to have an understanding of what the puppy needs.
There should be either a "The" or an "A" in front of family.
An understanding is a specific understanding. If written as, "I go without understanding", the meaning is that I fail to understand something (non-specific). The understanding here is about what th puppy needs (specific).
3.It serves an excellent "California-Mediterranean" menu.
The food served is specific. If written as, "The food is excellent", it is non-specific - it is just excellent.
I want to know why the before speed and no article before sound in sentence 1

and why an before understanding in sentence 2

and why an before excellent menu in sentence 3

I want to know if menu, speed sound and understanding are countable or non countable nouns and what is are the rules.
Thanks

Much depends on the context. You have to decide if the matter is specific or non-specific. For example, "I want water" - I don't care if it is blue or white, I want water. If you want a certain type of water, "I want the water in the blue bottle" - you want a specific type of water.