I googled "does speaker polarity matter?"
It said:
Yes, speaker polarity matters for the best sound quality:
Sound quality
When speaker polarity is incorrect, the sound quality can be affected. For example, if one speaker is wired incorrectly, it will be "out of phase" with the other speaker. This means that one speaker will move forward while the other moves backward, which can result in poor stereo separation and sound quality.
Signal cuts out
If the positive and negative speaker wires are mixed up, the signal will cut out. This is because one wave is positive and the other is negative, which results in silence.
Timing and coherence
The direction of the cable can affect timing and coherence. When the cable is connected in the correct direction, the sound will be more articulate and involving.
However, incorrect speaker polarity will not damage your amplifier or speakers. This is because the voltages received from a speaker with reverse polarity are no different than the speaker in correct polarity.
You can test the polarity of a speaker by using a small amount of voltage, such as a used double A battery. Touch the wires on the battery terminals to the speaker, one on the negative and the other on the positive. If the speaker pushes out when the polarity is correct, and pulls in when the polarity is wrong, then the polarity is correct.