Fill in the following blanks with suitable words : 

(a) Sounds are produced by ………….. objects. 

(b) The human voice box is called ………….. 

(c) Sound cannot travel in ……………….. 

(d) A set of three tiny…………in the middle part of ear passes on sound vibrations from the eardrum to the liquid in the cochlea. 

(e) The unit of frequency is …………..

(f) The time taken by an object to complete one oscillation is called………

(g) The shrillness of a sound is determined by the ………..of vibration. 

(h) Unpleasant sound is called………………. 

(i) Sound which is pleasing to the ear is called…………….sound. 

(j) A person having partial hearing loss can hear properly by wearing a device called hearing ……………on the ear.