What is the difference between "sound pressure" an "sound power"?

Answer 1

Sound pressure is the sound intensity (pressure) produced by a source at a specific point.

Sound power is the sum of the intensities at all points on a spherical or hemispherical boundary, expressed as power - in other words, the total amount of power radiated by the source.

This is a general definition, It might be easier to explain this if you gave a context.

Answer 2

Sound power or acoustic power Pac is a measure of sonic energy E per time t unit.
It is measured in watts, or sound intensity I times area A:
P_{\mathrm{acoustic}} = I \cdot A
The measure of a ratio of two sound powers is
L_\mathrm{w}=10\, \log_{10}\left(\frac{P_1}{P_0}\right)\ \mathrm{dB}
where
P1, P0 are the sound powers.
The sound power level PWL, LW, or LPac of a source is expressed in decibels (dB) and is equal to 10 times the logarithm to the base 10 of the ratio of the sound power of the source to a reference sound power. It is thus a logarithmic measure.
The reference sound power in air is normally taken to be 10−12 watt = 0 dB SWL.
Sound power is neither room dependent nor distance dependent, like it is with sound pressure or sound intensity. Sound power belongs strictly to the sound source. There is no decrease of power with distance.


Sound pressure is the pressure deviation from the local ambient pressure caused by a sound wave. Sound pressure can be measured using a microphone in air and a hydrophone in water. The SI unit for sound pressure is the pascal (symbol: Pa). The instantaneous sound pressure is the deviation from the local ambient pressure p0 caused by a sound wave at a given location and given instant in time. The effective sound pressure is the root mean square of the instantaneous sound pressure over a given interval of time. In a sound wave, the complementary variable to sound pressure is the acoustic particle velocity. For small amplitudes, sound pressure and particle velocity are linearly related and their ratio is the acoustic impedance. The acoustic impedance depends on both the characteristics of the wave and the medium. The local instantaneous sound intensity is the product of the sound pressure and the acoustic particle velocity and is, therefore, a vector quantity.
The sound pressure deviation p is
p = \frac{F}{A}
where
F = force,
A = area.
The entire pressure ptotal is
p_\mathrm{total} = p_0 + p \,
where
p0 = local ambient pressure,
p = sound pressure deviation.