We can talk about sweet and sound being “out there” in the world but in reality it is a useful fiction of sorts that we are “projecting” out into the world.

I hate to put on my Bishop Berkeley hat. Sweet and sound are things we can directly perceive. The very notion of something being "out there" independent of us is itself a mental model we use to explain our perceptions. We say that our sensation of sweetness is caused by a thing we call glucose. We can talk of glucose in terms of molecules, but as we can't actually see a molecule, we have to speak of it in terms of the effect it produces on a measurement apparatus.

The same holds for any scientific experiment. We come up with a theory that predicts that some phenomenon is to occur. To test it, we devise an apparatus and say that the phenomenon occurred if we observe the apparatus behave one way, and that it did not occur if we observe the apparatus to behave another way.

There's a bit of circular reasoning. We can come up with a scientific explanation of our perception of taste or color, but the very science we use depends upon the perceptions it tries to explain. The very notion of a world outside of ourselves is a theory used to explain certain regularities in our perceptions.

This is part of what makes consciousness a hard problem. Since consciousness is responsible for our perception of the world, it's very hard to take an outside view and define it in terms of other concepts.