2006 Acura RSX whining noise at 2500rpm

I have a 2006 RSX base model. got 134,000miles on it. recently it starts to making whining noise when the rpm gets to 2500-3000rpm. The car also started to have the cricket chirping like sound. Had the oil changed, tune up already. The sound seems to get louder, and the car seems to have less power. Especially when going up a slope you can hear the engine reving, and car don’t want to move. Before this car would go up these slope like it was nothing. My brother say the sound is coming from the engine. Any ideas?

The first thing to do is check the level and color of the transmission fluid.

If the engine revs but the vehicle doesn’t go any faster it points to a problem with the transmission.