Partly answering my own question, the reviewers on Amazon are saying that
regardless of audio quality, the Bose Triport headphones have a flimsy frame
that breaks easily.

I get the impression that half as much money spent on Sennheiser or Grado
would give better sound, and certainly better construction.

Which competitor most nearly matches the comfort and the
outside-noise-blocking of the Bose Triport?

MC wrote:
Partly answering my own question, the reviewers on Amazon are saying that
regardless of audio quality, the Bose Triport headphones have a flimsy frame
that breaks easily.

I get the impression that half as much money spent on Sennheiser or Grado
would give better sound, and certainly better construction.

Which competitor most nearly matches the comfort and the
outside-noise-blocking of the Bose Triport?

I haven't used the Bose Triport, but perhaps if you describe something
about them we might be able to come up with a match.

Do they use active noise concellation? Is that how they achieve this
blocking of outside noise? If so, you can find many examples of active
noise cancellation headphones in other brands. I'm aware of several
that Sennheiser makes. Other good brands include AKG, Koss, Grado, and
Beyerdynamic, although I dont' think all of them make active noise
cancelling headphones.

If they achieve this outside noise blocking via being a closed
headphone, you can find numerous examples of those as well.

Another thing that would be good to know is something about the general
tonal balance of the Bose. Are they bright, or rolled-off? Do they have
tons of bass, or kinda lean? If you know that, then you can compare to
other headphones.

What's comfortable about them? Because they are lightweight? Because
they have cushy pads? Because they put low pressure on your ears?

Headroom Corporation has a lot of good headphones, money back trial
period, specs on their website (including sometimes the actual noise
reduction figures) and salespeople that will be willing to talk with
you about your preferences. They are at:

http://www.headphone.com/

Also, check out this forum ("head-fi"):
http://headfi.com/

These guys will be willing to talk your ear off about headphones.

Mike

Look for a pair of Vintage Koss Pro 4AA headphones. Getting inside them
is like getting inside a soundproof box... and also prevents you from
spilling out.

Hey, you can even go new.

http://www.koss.com/koss/kossweb.nsf/p?openform&pc^fs^PRO4AAT

I have no connection w/Koss. But for isolation, they are unbeaten and
unbeatable. Heavy beasts.

Peter Wieck
Wyncote, PA

wrote:
Look for a pair of Vintage Koss Pro 4AA headphones. Getting inside them
is like getting inside a soundproof box... and also prevents you from
spilling out.

Hey, you can even go new.

http://www.koss.com/koss/kossweb.nsf/p?openform&pc^fs^PRO4AAT

I have no connection w/Koss. But for isolation, they are unbeaten and
unbeatable. Heavy beasts.

Pro 4AA's are approved by various governments as toture devices. But they
do sound fairly good.