Tom(s),
If you have an HD receiver, what you hear on the primary channel is 
what you have heard all along, allbeit in better quality.  My 
favorite station, WDRV 97.1 is sixties and seventies, a higher amount 
of music than some formats and clumps of commercials, less than 
some.  Their HD2 is "deep tracks" and I'm not quite sure what that 
means.  I have an HD radio at the office but not quite enough signal 
strength to hear the secondary channels on most downtown Chicago FM 
stations.  My office building is very FM resistant.  I would guess 
that probably ninety percent of Chicago FM is HD.  WBBM, our CBGS At 
07:36 PM 7/30/2011, you wrote:
>Hi, all.
>
>I am not sure if this will be considered by some to be "off topic", but last
>evening, I heard something on an FM broadcast station that has confirmed my
>long-standing suspicions about where commercial FM radio is going today.
>
>I simply thought it might be of interest to others.
>
>By way of introduction, I have noticed that the quality of many normal
>non-HD FM stations seems to have deteriorated over the past few years,
>especially in larger metropolitan areas.  By declining quality, I mean more
>commercials, less music, and what seems to be a much less diverse play-list.
>
>My theory had always been that normal non-HD FM stations were simply being
>operated for those who hadn't yet made the switch to HD radio, as kind of a
>necessary evil.  It just seemed to me that more resources and efforts were
>being put into HD stations, so as to come up with a better-quality and more
>appealing product.
>
>As many of you may know, I am currently traveling throughout the east coast,
>and am now spending some time with my wife's mother in the Trenton, New
>Jersey area.
>
>Last night, I was listening to W O G L--98.1 FM in Philadelphia.  In the
>past, that station had been an excellent oldies station, with what I think
>had been very good ratings.
>
>Now, the station has more of a "classic hits" format, with lots of talk,
>commercials, and other stuff between the music.
>
>Anyway, shortly before the top of an hour, the station ID was played,
>followed by a message that said something like this:  "If you want more
>music, more oldies from the 60's and 70's, and more home-town DJ's, tune to
>W O G L HD1".
>
>To me, this indicated, at least in this case, that the HD option was clearly
>being promoted over the normal non-HD programming.
>
>Am I onto something here, or totally "off base"?
>
>And, please:  to those in the broadcast business (like Lou )WA3MIX), I mean
>no offense whatsoever by these observations.
>
>HD radio has not yet arrived in the part of semi-rural west-central lower
>Michigan where I currently live, but if I lived in a bigger metro area, I
>have the feeling that HD radios would quickly be added to my wish list.
>
>73 from Tom Behler:  KB8TYJ