Quoted from Tomass:
Looking for some help with an odd speech issue. Speech works when I use the test button, but not in game. In game when there is speech, it sounds like static and someone whistling over it. Almost like someone whistling at a ballgame.
The whistling is one of the sounds the game can make, it sounds like yours game is playing it at the wrong time. This can happen if one or more of the signals from the CPU board are not making it to the Sound board properly. They leave the CPU board on J8 (right side of the CPU board) and enter the sound board on J3 (left most on the top of the sound board).
Try reseating these to see if that makes a difference. If you haven't already, you should reflow the solder on these header pins (all the pins on these boards for that matter).
If that doesn't help, run the sound test in diagnostics (instructions in the instruction booklet). This test verifies the connection between the CPU and sound board. Pressing the diagnostic button on the sound board itself only verifies the soundboard and ROMS themselves are functioning. The diagnostic test triggers each signal line one at a time. From this, you should be able to tell which one is not making it to the sound board. From there you can trace it to a wiring problem or a dead output on IC36 (PIA).