1. The part of the inner ear shaped like a snail is called the _______.   hammer   eardrum   cochlea   Hint Half-n-half Clue   2. The three little bones in the middle ear are the _______, the anvil and the stirrup.   cochlea   hammer   eardrum   Half-n-half Clue   3. Out of the following materials, the best conductor of sound is _______.   Steel   Air   Water   Half-n-half Clue   4. The number of sound vibrations per second is called _______.   frequency   time period   amplitude   Half-n-half Clue   5. If a flash of lightning is observed in a cloud 1650 m away and the speed of sound in air is 330 m/s, then the sound of thunder will be heard _______ s after the flash of lightning.   3   5   10   15   Half-n-half Clue   6. When sounds reach the _______ or tympanic membrane, they make it vibrate.   cochlea   hammer   eardrum   Half-n-half Clue   7. The _______ keeps the pressure in the middle ear the same as the outside air pressure.   Eustachian tube   semicircular canal   eardrum   Half-n-half Clue