- #1

acousticsnoob

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## Homework Statement

Acoustic tile which is locally reacting, for a frequency of 400 Hz, it has a normal-incidence specific impedance of 1500+i3700 (Kg/m2s). A plane wave in Air of 400 Hz sound with a pressure level of 86 dB in the absence of reflection is incident on the tile at an Angle X. How close must X be to grazing incidence for resulting sound presure level just at the surface of tile to be less than 83 dB? determine and plot the absorption coefficient as a function of the incidence angle X.

how do i solve this problem?

## Homework Equations

for air, rho*c=400.

Grazing angle X is to be close to 90 degrees. but how do i calculate this angle for given SPL levels of 86 dB and 83 dB?