What Is Yamaha's YPAO?

Yamaha's YPAO stands for "Yamaha Parametric room Acoustic Optimizer." It's a technology used in Yamaha's AV receivers, Hi-Fi receivers, and home theater systems. YPAO is designed to optimize the audio performance of your speakers in your listening environment by analyzing the acoustics of the room and adjusting various audio parameters accordingly. This helps to ensure that you get the best possible sound quality regardless of the layout or acoustics of your room.

For additional information please have a look here:
HOW YPAO™ WORKS IN YAMAHA HI-FI RECEIVERS

HOW TO CALIBRATE YOUR AV RECEIVER WITH YPAO™

EXPLORING THE LEVELS OF YAMAHA AUDIO ROOM CALIBRATION (YPAO™)