Longitudinal and transversal waves.

Interference of the waves on the water surface.

Reflection of the single circular waves and passing them through semitransparent wall. Shock waves. Principle of Huygens.

Two modes of oscillation in crystals. Phonons.

Generation of acoustic wave by loudspeaker.

Doppler effect in acoustics. The frequency of the detected signal is changed if the source and receiver move relatively each other.

Fourier Series. Harmonics of the signal.

Generation of the shock waves by moving body. Doppler effect.