Doppler effect (the sound source moving towards observer)

[desmond iking]

Homework Statement

the observer is stationary , but the sound source is moving towards the observer , i was told that the speed of sound relative to the observer doesn't change. why is it so ? in my opinion, the speed of sound relative to observer changed . because of v= f x (lambda) , as the frequency of sound is fixed , but the wavelength of sound waves now changed , (the wavelength now become shorter) , so the speed of sound realtive to the obersver is reduced . am i correct ?

Homework Equations

The Attempt at a Solution

 

[Simon Bridge]

The speed of sound in a medium is a property of the medium, not the source or the observer.