Negation in concurrent verbs

Question

I saw this sentence in my workbook:

スープは音を立てて飲まないのがいいマナーとされる。

and I found many cases of 音を立てて飲まない on Google.

This expression seems to mean "to not drink, while making sounds", instead of "to drink without making sounds", for which I would use 音を立てずに飲む.

What is the grammar point of such expression? Is this an exceptional or general case?

Answer 1

This expression seems to mean "to not drink, while making sounds"

I think this is where you went wrong. Think of 音を立てて飲む as one block, and you have a negation of that whole block. So more like

( NOT ( 音を立てて飲む ) = いいマナー ) とされる。

Of course, your 音を立てずに飲む is also correct, I prefer this version myself. However, they are both correct.