This part is a kind of semiconductor called BD3872FS.

Function of this product has Sound Processors.

Manufacturers : Rohm

Image and pinout :

Some of the text within the PDF file :

Sound Processors for BOOM BOX / Mini-component Stereo Sound Processors with Built-in 2-band Equalizers BD3870FS,BD3871FS,BD3872FS,BD3873FS No.10086EAT02 ●Description The Sound Pr ocessor with built-in 2 Band Equalizer, incorporates functions required for BOOM BOX and mi ni-component systems, such as input se lector, input gai n amp, vol ume, surroun d, tone (b ass, treble), an d lo ud speaker e qualizer (BD3872FS only). These functions can be controlled through the two-wire serial control. ●Features 1) Using external components, center frequencies and Q factors of the bass characteristics are flexible. 2) Providing a mute switch onto one of the input pins allows cross-talk suppression. 3) A surround function can be constructed without external components. 4) Energy-saving design resu [ ... ]

BD3872FS PDF Datasheet Download