i don't have my copy of Peopleware handy but here are some quotes on studies it references:
"Workplace Quality and Product Quality - Companies that provide small and noisy workplaces explain away complaints as workers campaigning for the added status of bigger, more private space. To determine whether noise level had any correlation to work, we divided our sample into those who found the workplace acceptably quiet and those who didn't. Then, looking at workers within each group who completed the entire exercise without a single defect:
> Workers who reported that their workplace was acceptably quiet before
the exercise were 1/3 more likely to deliver zero-defect work.
As the noise level gets worse, this trend gets stronger:
Zero-defect workers: => 66% reported noise level OK
1-or-more-defect workers: => 8% reported noise level OK
A Discovery of Nobel Prize Significance - On February 3, 1984, in a study of 32,346 companies worldwide, the authors confirmed a virtually perfect inverse relationship between people density and dedicated floor space per person. If you're having trouble seeing why this matters, you're not thinking about noise. Noise is directly proportional to density, so halving the allotment of space per person can be expected to double the noise. Even if you managed to prove conclusively that a programmer could work in 30 sq. ft. without being hopelessly space-bound, you still wouldn't be able to conclude that 30 sq. ft. is adequate space. The noise in a 30 sq. ft matrix is more than triple the noise in a 100 sq. ft. matrix, which could make the difference between a plague of product defects and none at all."
So everyone should just put on headphones, right? Peopleware says no.
"experiment done at Cornell -- they gave two groups a complicated task involving a long string of calculations. One group listened to music while performing the task, and one group had silence.
What they didn't tell either group is that the complicated string of calculations always returned the original number.
It turned out that not everyone figured this out, but of the people who did, a large majority came from the group that did not listen to music.
The theory apparently being is that listening to music is somehow engaging the part of the brain involved in creative thought, keeping it "busy" enough not to be able to look at the big picture of the task being performed."
All developers should consider their surroundings and how they affect their thought process. I actually stopped listening to popular music while developing, after I read this and some other studies about it's effect at keeping part of your brain (the language processing parts) occupied. I still listen to music part time, and try to listen to instrumentals only.