C++ OpenAL errors: missing OpenAL headers

I'm running on Lubuntu using Code::Blocks with GCC, and despite installing the OpenAL dev packages with the commands:

sudo apt-get install libopenal-dev
sudo apt-get install libalut-dev

It reports the error "no such file or directory" when trying to include the headers. The #includes I've attempted (in-case it's a naming issue) are:

#include <OpenAl/al.h>
#include <OpenAl/alc.h>

-

#include <AL/al.h>
#include <AL/alc.h>

-

#include <al.h>
#include <alc.h>

Which all produce the same file/directory not found error.

What do I need to do in order to get GCC to 'see' the OpenAL headers?

It's not a duplicate of:

How to compile OpenAL program with g++ (Ubuntu)?

Because if you read the answer for that question is to "Make sure you have alut installed". If anyone took 3 seconds to read the top of this question they will see that it is already installed. Furthermore that question doesn't deal with CodeBlocks.