Sound

Sound is a longitudinal wave vibration created by an object and transmitted through a solid, liquid, or gas.Particularly, sound means those vibrations composed of frequencies capable of being detected by ears.

Speed of sound through air

 * In dry air at 1 atmospheric pressure and $$0^{\circ}C$$ the speed of sound is $$331.4$$ $$m/s$$


 * The speed increases with temperature at the rate of $$0.61$$ $$m/s^{\circ}C$$


 * The speed of sound in dry air at 1 atmospheric pressure is then $$V=331.4+(0.610)t_c$$
 * $$t_c$$ = Air Temperature $$(^oC)$$

Speed of sound through gasses
The speed of sound through an ideal gas is expressed by the formula

$$v=\frac{\sqrt{\gamma = RT}}{M}$$

Where


 * v = speed of sound
 * R = universal gas constant
 * T = absolute temprature (K)
 * M = molecular mass of gas (Kg/mol)
 * The average molecular mass $$(M)$$ for dry air is $$28.95 g/mol$$
 * $$\gamma$$ = adiabatic constant
 * For air adiabatic constant $$\gamma =1.4$$

Doppler Effect
If a sound emitting source and listener move along the same straight line the listener will hear sound of the frequency:

$$f_o = f_s\left( \frac{v\pm v_o}{v\mp v_s} \right)$$


 * $$fs$$ = the source sound frequency


 * $$fo$$ = the observer sound frequency


 * $$vo$$ = the realative speed of the observer


 * $$vs$$ = the relative speed of the source


 * $$v$$ = the sound speed in this medium