>>With all of WUMB's signals, why isn't WUMB showing up?
is WHRB considered a commercial station? It's in the commercial band...If this counts non-comm/public
where's WGBH and WBUR (supposedly powerhouse ratings for latter?)
Stations that broadcast between 92.1 and 107.9 (or the AM band) are inherently commercial
unless they file with the FCC to operate as a non-commercial station. A few stations do so, I think WBUR 1240AM on the Cape is, for example. But many do not...the benefits of reduced filing fees and whatnot are outweighed by the programming restrictions.
Anyways, WHRB is indeed a commercial radio station, even though they are run out of a college and owned by (AFAIK) a non-profit organization (the Harvard Radio Broadcasting Corp). That's why they enjoy that "hands off" relationship from Harvard. WMBR has a similar deal in that they're owned by the Technology Broadcasting Service, not by MIT...although WMBR is, of course, a non-comm broadcasting in the non-comm band.
There are also a handful of grandfathered Class D FM stations that got bumped to the commercial band back in the 1980's. Even though they're in the commercial band, they are required to be non-commercial licensees. Locally, WBRS, WRBB, WHHB and WYAJ are all examples.
Stations that broadcast between 87.9 and 91.9
cannot operate as a commercial station; they must be non-commercial. That's why WUMB (and WGBH and WBUR) do not show up in the normal Arbitrons, although Arbitron is planning on ending that distinction due in large part to consistent strong showings by stations like WBUR. If you look at WBUR's ratings (via RRConline.org) they absolutely cream most other stations in the market in the key 25-54 demo. Only WBZ, WMJX and WRKO/WEEI (Red Sox) are serious competition to WBUR these days.