The physical character of sound
Sound: The pressure wave which is vibrated in the elastic medium.
Wave: The presentation of passing the energy from one place to another place.
Wavelength: The length of one cycle of the wave.
Frequency: The amount of the cycles within one second. Measurement is Hz.
Period: The total time to complete a cycle.
Velocity: The speed of the motion of the wave.
Velocity = Wavelength × Frequency
The velocity of sound are associated with the medium.
Density: The higher density medium results in higher velocity.
Elasticity: The higher elasticity medium results in higher velocity.
Energy: In the atmosphere, the higher temperature results in higher velocity, the formula as following:
Vs = 331 m/s + 0.6t
Therefore, at 20℃, the velocity is 331+20*0.6=343 m/sec.
Amplitude: The measurement of a molecule moving in the medium, it stands for the sound pressure level.
Root Mean Square: The root is 0.707 times of the biggest amplitude.
Average: 0.637 times of the biggest amplitude.
Resonate Frequency: The frequency of the object vibrating.
Free field: A clear space, without any reflection waves.
