Transcript Sound traveling from one medium to another

What is the absolute power of a sound with
an intensity of X dB IL?

What is the absolute power corresponding to 20 dB IL?
Answer: 10-10 w/m2

What is the absolute power corresponding to 80 dB IL?
Answer: 10-4 w/m2
What is the absolute pressure of a sound
with an intensity of X dB SPL?

What is the absolute pressure corresponding to 60 dB
SPL?
Answer: 2 x 104 or 20 x 103 μPa

What is the absolute pressure corresponding to 140 dB
SPL?
Answer: 2 x 108 or 20 x 107 μPa
Sound fields

Sound field: Any environment that contains sound
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Free field: Sound field without any reflections
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Anechoic room: Artificial free field with no echoes

Reverberant/echoic field: Sound field with reflections

Diffuse fields: Type of reverberant field with uniform sound intensity
throughout the field.
Sound propagation with distance in a free
field
I  1/(r2),
where I is the intensity of the sound,
P is the power of the sound
at the source, and
r is the distance from the source to the point of
measurement.

Sound pressure and distance
p  1/r
where p = sound pressure, r = distance from source
Sound propagation with distance in a field
with obstacles

Impedance: Opposition to vibration

Two forms:

Reactance (X)

Resistance (R)
 Remains
same across frequencies