60: Percent of UK adults estimated to be adversely affected by their sonic environments.
60: “The 60-60 rule asserts that you shouldn’t listen to music at a volume louder than 60% of maximum for more than 60 minutes at a time.”
70: The percent slower that sound moves on Mars than on Earth.
Sources: UK (pipedown.org), 60-60 (zdnet.com), Mars (nature.com)