Influence of overpressure on sound transmission through curved panels

A great deal of recent research related to the aeronautic industry has been devoted to the theoretical study of sound transmission through fuselage structures. However, the literature records few test data with reference to the influence of overpressure on sound transmission. In this article, the airborne sound transmission through curved panels under the condition of overpressure at the concave side has been investigated experimentally and it is shown that experimental results agree well with a theoretical prediction due to an infinite cylindrical shell model at relatively high frequencies. Discrepancies, which occur at lower frequencies, can be explained, inter alia, by the influence of the finite size and attached stiffeners of the panel.At frequencies higher than the corresponding ring frequency for the curved panel, both experimental and theoretical predictions reveal that the overpressure at the concave side tends to reduce the sound transmission loss at the rate of about 0.5 dB/10 000 Pa. While at lower frequencies, say well below the ring frequency, the overpressure may increase or reduce sound transmission loss of a finite panel depending on the shift of resonant frequencies resulting from the overpressure.