The statement you provided is not accurate. The frequency of a sound wave in a medium and the velocity of sound in that medium are independent of each other. They are determined by different characteristics of the medium.
The velocity of sound in a medium, denoted by "v," is determined by the properties of the medium, such as its density and elasticity. It is not directly affected by the frequency of the sound wave.
On the other hand, the frequency of a sound wave, denoted by "f," represents the number of oscillations or cycles of the wave that occur per unit of time. It is a measure of how many times the particles of the medium vibrate back and forth in a given time period. The frequency is typically measured in hertz (Hz).
So, if the frequency of a sound wave in a medium changes from "f" to "4f," it means the number of cycles of the wave occurring per unit of time has increased. However, this change in frequency does not have any direct impact on the velocity of sound in the medium. The velocity of sound will remain the same unless there are changes in the properties of the medium itself.
In summary, changes in the frequency of a sound wave do not cause changes in the velocity of sound in the medium. The velocity of sound is determined by the properties of the medium, while the frequency represents the number of oscillations of the wave per unit of time.