The higher the frequency of a sound wave the higher the pitch. (Same with the lower). Therefore low sounds have a low frequency. However volume-wise it's a different story because sound is measured...
High frequency is used because of the the size of antennas used to transmit and receive the communications signal. The higher the frequency the smaller the antenna.
As the frequency becomes higher then its wavelength would decrease. In case of mechanical waves such as sound waves higher frequency means higher the pitch. In Sanskrit it is known as 'shruthi'....