Question on Russian phonetics

[Loren A. BILLINGS]

Dear colleagues,

I'm wondering if any of you know a phonetic distinction between the
following two _so^cetanija_:

1.  pol komnaty "floor of room"

2.  polkomnaty  "half of room"

I already know the following:  Whereas /o/ after a non-palatalized
consonant reduces to [a] or [@] (=schwa), depending on whether it's in
first-pretonic unstressed syllable or not (e.g., /moloko/ --> [m at laKO]
"milk"), the /o/ in _pol_ "1/2" always retains lip-rounding (i.e., example
1. above is never *[p at l...] or *[pal...], but always [pol...]).

Still, it seems to my ear that 1. and 2. are phonetically distinct; 1.
behaves like a so-called stump compound (like _zavkafedry_ "department
head"), while 2. is a combination of two morphological words with separate
word stresses (but phrasal emphasis only on the second word).

I'd be very interested in instrumental evidence that these two differ.
Please distribute this query to anyone you know who works on Russian
phonetics.

Best,  --Loren Billings (billings at rz.uni-leipzig.de)