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Vibration-based sound power (VBSP) methods based on elemental radiators and measurements from a scanning vibrometer have been shown to be accurate for flat plates and cylinders. In this paper, the VBSP method is extended to account for simple curved structures, with a constant radius of curvature. Data are also presented that suggest the VBSP method is more accurate than the ISO 3741 standard for measuring sound power when significant background noise is present. Experimental results from ISO 3741 and the VBSP methods are compared for three simple curved plate structures with different radii of curvature. The results show good agreement for all three structures over a wide frequency range. The experimental results also indicate that the VBSP method is more accurate in the low frequency range where the curved plates radiated relatively little and significant background noise was present.

Research has shown that using acoustic radiation modes combined with surface velocity measurements provide an accurate method of measuring the radiated sound power from vibrating plates. This paper investigates the extension of this method to acoustically radiating cylindrical structures. The mathematical formulations of the radiation resistance matrix and the accompanying acoustic radiation modes of a baffled cylinder are developed. Computational sound power calculations using the vibration-based radiation mode (VBRM) method and the boundary element method are then compared and shown to have good agreement. Experimental surface velocity measurements of a cylinder are taken using a scanning laser Doppler vibrometer and the VBRM method is used to calculate sound power. The results are compared to sound power measurements taken using ISO 3741.

The theoretical development for computing sound power using acoustic radiation modes is well documented. However, an experimental validation and comparison with other sound power measurement standards over a wide frequency range has not been presented. This paper compares experimental results from an acoustic-radiation-modes-based sound power measurement method to results obtained using ISO 3741 in two scenarios. First, sound power measurement results from a single simply-supported baffled panel are compared. A comparison of sound power measurements of two simply-supported baffled panels is then presented. Results between the two methods for the single panel show a maximum one-third octave band difference of 2.2 dB between 200 Hz and 4 kHz with an overall difference of 1.7 dB. For the two-panel system, the maximum one-third octave band difference is 1.6 dB with an overall difference of 0.7 dB. It is also shown that in the two-panel case, the sound power from each panel can be measured individually using the acoustic radiation modes approach and summed to obtain the overall sound power as measured using ISO 3741.

Acoustic radiation modes have recently regained the attention of the literature, with applications ranging from active structural acoustic control to acoustical holography. Typically the calculation of these modes requires boundary element methods for all but flat plate and full sphere geometries. This paper presents a radiation mode formulation for cylindrically curved structures with small curvature, based on the uniform theory of diffraction. This formulation shows promise, as it produces analytical expressions for the radiation resistance matrix, leading to computationally efficient radiation mode calculation. Radiation modes are shown for cylindrically curved plates, and the calculation of sound power with these modes is compared to that calculated using boundary element methods. The extension of this formulation to other curved structures is discussed.