Medium
Which of the following frequency of sound can't be heard by our ears?
Explanation
Explanation
The human ear can normally hear sounds with frequencies roughly between 20 Hz and 20,000 Hz. A frequency of 8 Hz is below this range (infrasound), so it cannot be heard, while 38 Hz, 10800 Hz, and 6800 Hz all fall within the audible range.
PRO TIP
Re-check your working by substituting the answer back into the original question.