A device was designed to simultaneously measure the temperature and speed of sound (using a time-of-flight technique) and then calculate the percent ethanol in an ethanol/water mixture. The speed of sound of an ethanol/water mixture varies linearly with percent ethanol when the concentration of ethanol is at least 40% or greater. The temperature of the mixture shifts the sound speed essentially changing the y-intercept. Data will be presented to demonstrate the resolution and precision of the device.
Cheyne et al. (Wed,) studied this question.