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Two hydrophones are mounted side by side with a separation distance of 20 mm for the frequency range 1–10 kHz. In an anechoic chamber, the probe is validated with a microphonic intensity probe for acoustic power measurements of a reference sound source. The results are compared and agree very well. Directional characteristics of the probe are carried out. Then, an experimental setup is developed in a small cavity (2 × 1 × 0.8 m3) filled with water. A hydrophone as projector is put in the middle of the tank. The characterization of this test facility is done in terms of the time response between the different boundaries and the receiver. The sound power measurements obtained by an hydrophone associated with a gating system to simulate free-field and those obtained by the hydrophonic probe are compared. Sound source localizations are also investigated. The results are in good agreement in spite of the small bounded water tank. This technique seems to be very interesting to study material characteristics like transmission or absorption and source localization.

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For several years, aeronautical industries have wished to improve internal acoustical comfort. In order to make it, they need metrological tools which are able to help them to spot acoustical sources and the associated path in a specific frequency range (i.e., for helicopters’ internal noise: 1000–5000 Hz). Two major source’ localization’ tools exist: holography and beamforming, but these two techniques are based on a free field’s hypothesis. So, problems appear when these techniques are used in a reverberant medium. This paper deals with the study and the comparison of holography and beamforming results in an enclosed area. To complete the study, intensimetry is also implemented to have information on the energy propagation. In order to test the performances of each method, two reflecting panels are put at right angles to create a reverberant environment, in an anechoic chamber. We seek to locate loudspeakers clamped in one panel, in the presence of parasite loudspeakers located on the other one. Then, a parametrical study is led: localization and number of sources, coherent or noncoherent sources. Thus, using limitations, precautions to take, and a base of comparison three methods are put forward. Finally, some envisaged solutions to limit problems of reflections (signal processing, overturning, etc.) are presented.

The purpose of our experiment is to learn the influence of stiffening on the acoustic response of steel plates. The investigation is carried out on a rectangular plate that is clamped in an opening (1.20 × 2 m2) between a reverberant room and a test room. The sound transmission loss is determined by using two different methods: a method that is based on the sound pressure measurement and the two-microphone intensity method. The mean radiation efficiency is obtained by measuring the panel vibration velocity with a regular mesh. The measurements are made over a frequency range from 250 to 10 000 Hz for a diffuse field excitation. The following series of samples is tested: a 1.5-mm-thick-steel plate; a plate reinforced with uniformly spaced tubular stiffeners; a plate reinforced with uniformly spaced line stiffeners; and a corrugated panel (the space between the corrugations is the same as the space between the stiffeners). The acoustic effect of variation of bending stiffness is discussed, and all the experimental results provide comparison elements for computed results.