I listened only to Sample 2, normal and then inverted. They sound the same to me. I listened on decent quality Sony headphones.
Usually a difference can be heard after inverting polarity only with low frequency content. And as I explained earlier, it's due to non-linearity in the speaker or headphone drivers, not the ear's ability to distinguish polarity.
ethan - please make the clarification of what can be heard in careful tests designed to point up the differences and what is perhaps a "practical" decision to ignore polarity in normal music mastering
polarity as I point out below (previously in this thread) can equivalent to substantial harmonic vs fundamental phase shift for asymmetric waveforms
and the audibility has been tested by recognized researchers, published in Audio Engineering Society Journal
and since no one seems to actually look back or even clik on links:
edit: rethought dither and concerned that I may not have LTspice waveform data compression turned off so I reposted as audio.zip in the same diyAudio thread
https://web.archive.org/web/20110101113016/http://www.ocf.berkeley.edu/~ashon/audio/primer1.htm does concentrate on phase coherence - some of the info supports absolute polarity discrimination - page down past the missing graphs
Although not in large numbers, previous research in investigation of the audibility of phase distortion has proven that it is an audible phenomenon. Lip****z et al.  has shown that on suitably chosen signals, even small midrange phase distortion can be clearly audible. Mathes and Miller  and Craig and Jeffress  showed that a simple two-component tone, consisting of a fundamental and second harmonic, changed in timbre as the phase of the second harmonic was varied relative to the fundamental. The above experiment was replicated by Lip****z et al., with summed 200 and 400 Hz frequencies, presented double blind via loudspeakers resulting in a 100% accuracy score.
the 2nd harmonic relative phase shift test does amount to a test of polarity inversion audibility when the phase between the fundamental and the 2nd shift relatively by 180 degrees
don't confuse the 180 degree phase shift of symmetric waveform, 1/2 period delay with polarity inversion - polarity can only be seen with a asymmetric waveform - requires a specific harmonic structure
200 Hz + 400 Hz/90 degrees sines 1:1 amplitude:
no amount of phase shifting, time delay of the above waveform will let you put the positive and inverted version on top of each other - both have 0 DC component, and a absolute polarity
reading diyAudio and hydrogenaudio threads on the subject shows much confusion about the basic terms, assumptions
Edited by jcx - 3/20/14 at 12:57pm