With the Yamaha Intelligent Acoustic Control (IAC) feature, you can enjoy playing your digital piano at a lower volume in a quiet home environment. Before IAC was introduced, playing at a low volume resulted in a loss of treble and bass. With the development of IAC, the instrument automatically adjusts the balance of bass and treble, creating a more realistic sound with more depth. Additionally, the volume dial automatically makes fine adjustments to the overall sound of the speaker system (EQ) when played at a low volume. The ability to retain a rich and balanced sound on a digital piano, regardless of volume, ensures the highest sound quality.