The ktv sound is louder or the square sound is louder

This is actually not good to judge. Because there is no specific KTV speakers and square speaker models, is not good to compare. But I'll give you a rough analysis. If it is a general square dance with the speaker, probably in the 90 ~ 100 decibels of sound pressure level. If it is a large performance with a set of 24 linear array speakers, you are at one meter is about 150 dB sound pressure level. Good KTV speakers up to 110 ~ 120 dB sound pressure level. So, it's not a good comparison, depending on the speakers. Look at the above data, I believe you should have a number in mind.