Art Ludwig’s Sound Page : Music and human hearing contains information on the softest and loudest sounds we can hear, the range of frequencies we can hear, subjective vs. objective loudness, how we locate the source of a sound, and sound distortion. The human ear is a truly remarkable instrument. At one point in ludwig’s life he designed Electronic Counter Measures (ECM) systems for the U. S. military. The primary function of an ECM system is to detect an enemy before he (it’s rarely a she) detects you, for self-defense. It is interesting to compare the characteristics of a good ECM system and human hearing