Home professionals like realtors use ultrasonic measuring tools to quickly measure the size of rooms. (Ultrasound waves are pressure waves like regular sound, but they have an oscillation frequency that is too high for our ears to detect.) These instruments work by sending out a pulse of ultrasonic sound, then measuring the time it takes for this pulse to reflect off a wall and return to the device. If you used such a device on a particularly hot day, would you expect to measure the length of a given room as longer or shorter than on a cool day?