Use orientation sensor to set Ambience
It would be useful to use any built-in orientation sensor and/or timer/clock to set an ambience.
For example, placing the device screen-down for 15 seconds between the hours of 0900 and 1700 automatically invokes the silent ambience; and turning it over so that it is screen-up for more than 15 seconds invokes a standard noisy ambience. There are other possibilities.