How does the sound produced by a vibrating object in a medium reach your ear ?

Sound produced by irregular vibrations of a material is

How does a gecko produce sound ?

We have learnt that vibration is necessary for producing sound. Explain why the sound produced by every vibrating body cannot be heard by us?

Assertion (A) : The pitch of the sound produced by the vibrating string can be changed. Reason (R) : The pitch of the sound can be changed by changing the length, tension and thickness of the vibrating string.

Which of the following statements are correct? (i) Sound is produced by vibrations. (ii) Sound requires a medium for propagation. (iii) Light and sound both require a medium for propagation. (iv) Sound travels slower than light.