However, if you attend a conference and find your accommodation is noisy, you might not have brought any device that can generate a continuous stream of white noise.
This MIDI file can be played on most mobile phones as a "ringtone", and its size is less than 2 kB but it still gives 1 hour of continuous noise (which usually works better than setting a shorter file to repeat).
"White noise" MIDI file
May sound bad on some devices.
It should sound like this (but much longer).
It is not true white noise because most phone-based synthesizers can't do that. Instead, I tell your phone's tone generator to play an impossibly low violin chord containing all 12 pitches of the chromatic scale. On some synthesizers, this results in a mingling of harmonics that approximates white noise. But on other synthesizers you just get a cacophonous rumble. Your mileage may vary.