Sound waves

Sound waves propagates from a hotter air region to a colder air region. What is the wave phenomenon that will happens?
Gelombang bunyi merambat dari kawasan udara panas ke kawasan udara sejuk. Apakah fenomena gelombang yang akan berlaku?

A Reflection
    Pantulan

B Refraction
    Pembiasan

C Diffraction
    Pembelauan

D Interference
    Interference

Answer : B

Refraction occurs when waves propagates from region with different densities.