The sounds may vary from the <em>wavelengths</em>. The longer each wavelength is, the lower the pitch, and the shorter each wavelength is, the higher the pitch.
That is because their pitch is different. Pitch depends on the frequency of a sound wave. ... Some animals can hear sounds at even higher frequencies. The reason we cannot hear dog whistles, while they can, is because the frequency of the whistle is too high be processed by our ears.
