What is sound? … Sound is a mechanical wave produced by vibrations that travel through a medium, such as air, water, or a solid.

waves

What is a wave? … A wave is a disturbance that transfers energy from one location to another.

• Transverse waves:
• Longitudinal waves:

• frequency, $f=1/T$
• period, $T=1/f$
• angular frequency, $\omega=2\pi f$
• speed of light, $c=f\lambda=\omega/k$
• wavelength, $\lambda=c/f$
• energy, $E=h\text{v}$
• wavenumber, $k=2\pi/\lambda=\omega/c$
• no. of cycles, $N=ft=t/T$

harmonic waves

For a sinusoidal sound wave traveling in the positive (x)-direction:

$p(x,t)=p_m\cos(\omega t-kx+\phi)$