What is meant by inverting is the top of a waveform becomes the bottom of the waveform as it leaves the crack or whatever and conversely the bottom becomes the top. It does not matter inverse or not as your ear/ brain can not tell the difference between compression or rarefaction. What will be a problem is if one channel is out of phase with the other. this will cause a dramatic loss of low frequency and muddy mids.
You can try this, Remove one speaker wire from an amp and reconnect with pos and neg swapped. Turn on and if you have a balance control slowly turn it from center to either side and note what happens to the sound. next slowly turn to the other side. All the way to the left and the right will have good bass but when centered bass will be lost. Plus because the right and left sound fine listening to them singularly that exemplifies the fact that you can not determine inverted or normal signals.
End of story
