ᐅ Should partition walls be built all the way up to the ceiling?

Dear all,

Our drywall installer has set up the stud walls as shown in the photo.

The ceiling will be dropped later. I am wondering if this is correct or if the walls should have been built all the way up to the original ceiling? Especially concerning sound insulation.

As it is now, the stud wall meets the dropped ceiling.

What do you think?

Thanks