I understand that harmonics are integer multiples of a fundamental frequency. Also, that the relative strengths of the harmonics are what make the same note on different instruments sound different. Why are these other frequencies made? How many integer multiples are there? Why do our ears read the 'fundamental frequency' and not any other? Is it simple because it's the lowest frequency it can hear? If a note is played and makes a 15 Hz frequency, below the hearing level, will the harmonic of 30Hz (within hearing range) be picked up by the human ear?