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 Processor with built-in 2 Band Equalizer, incorporates functions required for BOOM BOX and mini-component systems, such as input selector, input gain amp, volume, surround, tone (bass, treble), and loud speaker equalizer (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 resulting in [ ... ]

BD3872FS PDF Datasheet Download