sound waves are usually affected by temperature but is not affected by pressure. how come?

Answer 1

It is possible to have bands of temperature layers. These bands create distinct sound wave aberrations. With pressure it is difficult to create bands, instead there are slowly changing gradients. You can observe both temperature and pressure impact upon sound waves in the atmosphere and also under water.

Answer 2

sound is affected by both temp and pressure, because the speed of a sound wave depends upon the properties of what it is traveling through.
One type of property that affects the wave speed is inertial properties and the density of the medium the wave is traveling through is inertial property. The greater the mass density of the medium the slower the wave travels. As an example, sound travels about 3X faster in Helium as in air.
Since the speed of sound in air depends upon the properties of the air, temp and pressure change the sound wave speed.The pressure of air will effect the mass density and the temperature will effect the elastic properties of the air.

Answer 3

They most definitely are affected by pressure. The higher the pressure, the greater the density, and the greater the velocity of the sound wave.