I can always tell which season I am watching by his voice which seemed to get darker/richer as the series progressed. Season 9 is my favorite because his voice has clearly aged but it has taken on such a richness and the cadence adds to the series. I also noticed in the later seasons he appeared less and less on camera. I am guessing they probably had a set up where he didn't have to go on the set anymore. I was not bothered by this at all. Bob really gave us his all on UM. I have always had a great respect for him.

I can tell if it's an early season (5 or earlier) or later season (after 5 or 6) based on the sound of his voice. The last couple seasons where his voice is noticeably weaker are a little sad to listen to.

The last couple seasons where his voice is noticeably wear are a little sad to listen to.

Yes - coupled with that, there's an obvious decline in the show's budget (shot on tape, anonymous sound stages instead of actual locations, no grand old sets or crowds of costumed extras like in the old "lost loves" segments) that make them a bit of a downer. :(

I might not be able to tell exactly which season, but whether it's the first few, the middle years (i.e. most of the 90s) or definitely the last several. Agree with marlins3 that hearing Stack's voice in the final few seasons can be sad.
The background music can be as good an indicator as Stack's voice as to a given point in the series.

I can't tell you what season it is by his voice, but I can by the segment. :)

That being said, though, I can absolutely tell Stack's voice has gotten weaker in the final seasons of the Stack UM episodes. :(

I can't tell you what season it is by his voice, but I can by the segment. :)

That being said, though, I can absolutely tell Stack's voice has gotten weaker in the final seasons of the Stack UM episodes. :(

And that's pretty amazing given he was 70 when season one aired.

It's really the last two seasons where it was impossible not to notice. It's sad to hear his voice, especially during that last season.

It was sad to hear Stack's voice changing before his death. Even in baseketball when he was about to be 80 years old he sounded and looked great

Did he have prostate cancer while the show was still on the air?

There is something about his voice in seasons 1,2 and 3 that are very meditative and soothing to me...to the point where I will play them continuously and repetitively just to have that kind of background "comfort." I know for sure I'm not alone, ha!

Did he have prostate cancer while the show was still on the air?

Probably so, even if it wasn't yet diagnosed. The show ended in 2002 and he was diagnosed that same year. I have read the show ended because of his illness, but I'm not 100 percent certain about that.

Probably so, even if it wasn't yet diagnosed. The show ended in 2002 and he was diagnosed that same year. I have read the show ended because of his illness, but I'm not 100 percent certain about that.

I think (what turned out to be) the final season was already complete at the time of his illness, and his passing shortly thereafter effectively ended the show.

I agree that the Lifetime seasons can be tough to listen to sometimes, though his voice is stronger in some episodes than others (and he always looked great when he appeared on camera).

As far as I can tell, the last material he recorded was the update to the Pond/Gaddis murders, which were resolved in mid-August 2002. (He died in May 2003.)