text: which one of the following frequencies of a wave in the air can be heard as an audible sound by the human ear? a: 0.10 hz b: 10 hz c: 1,000 hz d: 100,000 hz the correct choice is "c: 1,000 hz."  if you go to a piano keyboard, the a below "middle c" is at 440 hz.  every time you jump up one octave to the next a, you double your frequency, so the a above middle c is 880 hz, and the one above that is 1760 hz.  since 1000 hz falls between those two (obviously audible) notes, it must be audible itself.  in fact, every half-step (walking up the keyboard, both black and white keys) is about 6% higher in frequency.  as it turns out, the b and c above middle c are at about 987.8 and 1046.5 hz, respectively, so your 1000 hz tone is between them.