Determination of complex resonant frequencies in rooms by using electromagnetic/acoustic analogies

An efficient procedure for the determination of complex resonant frequencies in rectangular and cylindrical rooms having absorbing floor and ceiling is presented. At the beginning, the exact solutions for nonuniform sound field are derived for both types of rooms. On the basis of these solutions, a transcendental equation for the complex resonant frequencies calculation is obtained. This equation is transformed to a convenient form and numerically solved. Resonant frequencies and damping factors are obtained as real and imaginary parts of the complex resonant frequencies, respectively. The influence of the acoustic admittances of absorbing walls on the resonant frequencies, compared to an idealized room, is illustrated and discussed.