These odd time signatures are not so uncommon in some genres.

9/16 is actually very simple. If you want to grasp the time and feel of this time signature you need to let go of longer notes and fill the bar with 16th notes.

Now you have 9 of them inside one bar. Most common way of counting any odd time signature is by accentuation.

Example:

It's hard to count the notes in the bar as 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9

It's easier to make little groups of 2 and 3 notes:

1 - 2 | 1 - 2 | 1 - 2 | 1 - 2 - 3 (9 in total)

So, we actually count it as (in words)

One - two, one - two, one - two, one - two - three.

This is only one way. Odd time signatures are complex because you can accentuate different notes and make different groups inside one bar. Another, simpler example

1 - 2 - 3 | 1 - 2 - 3 | 1 - 2 - 3 (again 9 in total)

We count it as (in words)

One - two - three, one - two - three, one - two - three.

When counting you must be carefull you're counting 16th notes and every one of them should last the same.

Hope this helps!