1. The process by which sound vibrations are produced in pipes is known as _______.   resonance   rarefaction   reflection   refraction   Hint Half-n-half Clue   2. The repetition of sound which is reflected from an object is referred to as _______.   the amplitude   an echo   the pitch   Half-n-half Clue   3. Dolphins use infrasonic vibrations to locate objects and their prey.   True   False   4. The upper limit of frequency that can be heard by the average human is about   20000 Hz   2000 Hz   200 Hz   200000 Hz   Half-n-half Clue   5. The apparatus used in a ship to find out the depth of the sea underneath is called _______.   sonar   bell jar   tuning fork   Half-n-half Clue   6. The number of sound vibrations per second is called _______.   time period   amplitude   frequency   Half-n-half Clue   7. The three little bones in the middle ear are the _______, the anvil and the stirrup.   hammer   cochlea   eardrum   Half-n-half Clue