I have a few tips for a ya:
1. Try reducing the number of 3D objects (including desks). Increases the old school vibe.
2. Ever thought of distorting Baldi's voice? This would really give the effect of an old, crappy audio codec.
3. Distort other sound effects too... or maybe use a synth instead.
4. Try using an old school voice synth like Chipspeech or Alter Ego.
5. Please set the smoothness of the materials to 0 or, even better, use an emmisive material