Open Plan Noise

I moved into a new open plan office this week, and its still being refurbished. At each entrance, there is a dispenser like this one:

I assumed it was there because of the building work noise, but today I saw people wandering around with ear plugs in, even though no workmen were present. It became clear that these are not available due to the refurbishment work, rather due to the fact its an open plan office!