I don't know of a way around it, if both parts are using the same instrument, even on different layers. Maybe use a dynamic to raise the volume on the unison note?

This has been a complaint going back to the earliest use of instruments in Finale and other notation apps. Bad news and good news:

Bad news: Are you using the same instrument and player for both parts? If so, the player will sound only one note from the virtual instrument (VI) on a unison note. There's no workaround for this...

Good news: ...except to assign a different instrument library or a different player (Aria is a player but so is UVI, Kontakt and many others) to that second part. I've never tried different players using the same VI. As far as I know, Garritan supports the Aria player only. The Aria player does support libraries of other types including many that are free to download and use.

If using a male ooo or ahhh, there are libraries that can give you a different VI for each part.

I think we might be expecting too much from Finale's playback and today's technology. With real singers, it's perfect. Even using a DAW, you would have to use different samples and different CC data to emphasize the individual voices.

Set up a different bank with an ARIA player for each voice. Even if you use the same sound (in each of the banks/ARIA players), then you can, in my experience at least, hear all staves indiviually at whatever level you set without any voices dropping out

>Set up a different bank with an ARIA player for each voice. Even if you use the same sound (in each of the banks/ARIA players), then you can, in my experience at least, hear all staves indiviually at whatever level you set without any voices dropping out<

Cool! I wondered if it might but didn't want to suggest that since I have no first hand knowledge that works. Thanks for chiming in.

You could even fuss with one of the parts ever so lightly in the Aria player Controls section to make it sound slightly different, or use a separate Aria instance to change the equalization slightly--or even alter A440 to A442, which might be realistic considering some tenors I've heard ;-).

I am so frustrated by "singer" sounds in almost any program that I usually use Strings or other instruments I am not using for accompaniment to simulate the singer parts.

Good luck with your project; usually one can come up with something until the live singers arrive.

I like clarinets

I’ve used saxes in the past, but for learning tracks, it’s piano.

Bassoons, bassoons, bassoons (for medieval vocal music)

Someday, when I retire from my day job, I will treat myself to Dominus Choir Pro from these guys (already have Kontakt)

https://www.fluffyaudio.com/

It's not the money so much but I anticipate that each track takes a tremendous amount of time that I just don't have. I'm not performing my normal tasks but my day job has found plenty of work for me so that's good. My music gigs have dropped by 80% but the church work takes 10x longer to do pulling service music together from the volunteers. That is not an exaggeration—preparing charts is no different but getting tracks from the singers and players, assembling and editing.

Of course, it beats watching Netflix all day.

Someday, when Publisher's Clearing House shows up with the sizable check they have been practically been promising me for decades, I'm going to hire live singers and instruments.

(Not holding my breath.) :-D