Help me identify this IC
It's some application-specific integrated circuit (ASIC), designed to work in musical greeting cards, toys and the like. I doubt that you'll be able to find much information on that specific one, let alone a datasheet.

It most likely contains nothing but a RC oscillator for timing, a mask ROM programmed at the chip fab with the client-specific audio data, a rudimentary trigger circuit for the sound activation and some control logic to tie it all together.  

I don't think that it contains a microprocessor, a "proper" digital-to-analog converter or that it stores PCM audio, as that would be unnecessarily complicated (more complicated -> more chip area -> more expensive). My guess is that the audio data is stored as an already pulse density modulated bitstream, which is simply output one bit at a time to the speaker driver without any low pass filtering other than the speaker itself.