I am looking for terms that define noise, as is particularly heard in a newspapaer office. It is loud, but not loud enough to be called a din/ruckus/cacophony.
There is 'clamour' (US: 'clamor')
Clamour - noun
1 - a loud uproar, as from a crowd of people: the clamor of the crowd at the gates.
4 - any loud and continued noise: the clamor of traffic; the clamor of birds and animals in the zoo.
There is also 'hubbub'
Hubbub - noun
1 - a loud, confused noise, as of many voices: There was quite a hubbub in the auditorium after the announcement
Agree with Marv that clamor and hubbub are nice ones for the sustained noise of voices in a room.
You might also consider racket, which I think suggests a more abrasive sound than either of the above, perhaps one punctuated by the tapping of journalists fingers on keyboards.
1 : confused clattering noise : clamor
2 a : social whirl or excitement
Although Oxford Dictionary’s entry for “buzz” includes the notion of “continuous”:
1A low, continuous humming or murmuring sound, made by or similar to that made by an insect: the buzz of the bees a buzz of conversation;
I usually use, perhaps redundantly, and see it with “constant” (which I suppose makes this a two-word answer), as in this example from ‘The Smouldering Flame’ by Anne Mather (via Google Books):
… she doubted if he had even heard her above the constant buzz of conversation all around them.”
A "dull roar"?
n. a relatively quiet degree of noisiness.
More suggestions - Rumble:
a low heavy continuous reverberating often muffled sound (as of thunder) - Merriam-Webster.com
1. a rattling sound (as of hard bodies striking together)
3. noisy chatter -Ibid.
From which, Commotion:
4. a : an agitated disturbance : to-do
b. : noisy confusion : agitation - Ibid.
a low, indistinct, continuous sound, as of a stream, far-off voices, etc.
If a short phrase is acceptable, how about speech noise:
Coping with Speech Noise in the Modern Workplace
Hustle and Bustle - energy and excitement; confusion and business