How are you generating the keyboard audio? General MIDI? VST? other? How are you recording? Are you exporting to stereo or mono?

I know nothing about these things, so I am using the default settings. The files are VST. All elements are Finale instruments (Garritan): Choir Aahs and Steinway Piano. As for exporting, I am just clicking on Export/Audio File. Is that the info you are asking for?

By the way, I am not trying to achieve high level audio. I'm just sharing song files with people whose input could be helpful.

Ok but how are you importing the vocal? Are you processing it at all on export?

Normally, export audio is straightforward—what you hear on playback should be how the track sounds on the bounce.

Lots of variable in Windows. You need to take us through the process so that we can try to identify what’s happening.

Vocal sounds (from almost any affordable package) are notoriously problematic. I tend to use a wind instrument not otherwise used in the arrangement to simulate the voice. SoftSynth oboe is a stalwart, since the SoftSynth instrument has no range limitations and definitely stands out.

Yes, I’d doing a demo, I’ll use a melody instrument like a synth flute even on choral mockups. Never choir ooohs or aaahs. 

These replies may be on track. I'm using Choir Oohs. I'll play around with synth flute as oboe, and see if that takes care of it.

Finale 25, Win 7