pref=20*10^-6;
rhoair=1.2;
speedofsound=343;
M=1;
rhomaterial=3000;
R=N[(3*M/(4*Pi*rhomaterial))^(1/3)];
A=4*Pi*R^2;
Lp=85;
f=30;
F=A*pref*10^(Lp/20);
d=F/(4*Pi^2*M*f^2)

Lp=60;
SoundPower=A*pref^2/(rhoair*speedofsound)*10^(Lp/10)
f=100;
d=(pref^2/(rhoair^2*speedofsound))^(1/3)*10^(Lp/30)/f