This thesis deals with the problem of noise. Sound is a constant presence in our lives. Most of the times it is something wanted and it serves a purpose, such as communication through speech or entertainment by listening to music. On the other hand, quite often sound is an annoying and unwanted by-product of some other activity necessary to us. This is what we usually refer to as noise. Noise does not simply create an unpleasant environment but can severely affect human health and have a serious impact on the natural environment as well. The noise pollution problem is addressed in many different ways: by clever urban planning, for instance, and by providing the heavily exposed buildings with acoustic barriers and insulation. Legislation also provides a limit on the maximum acceptable noise levels in many contexts such as working environments, discotheques and music headphones devices. An important effort in the fight against noise is obviously placed at the source of the problem itself, trying to make our tools and devices quieter. In order to do so it is essential to understand, and eventually be able to model, the processes through which sound is produced and propagated. The objective of this work is to develop and to employ experimental methods, based on the particle image velocimetry (PIV) measurement technique, for the estimate of the emitted sound from flow field measurements. In particular, the focus will be on the study of the noise that is generated by the unsteady loads on solid bodies immersed in the flow. The proposed technique, based on time-resolved PIV measurements, provides insight into the sound sources that is not possible to achieve with other established experimental methods. It also permits experimental investigation in those situations where other measurements would not be possible, for example, in the presence of a noisy environment or when a suitable anechoic tests facility is unavailable. In addition, it allows the estimation of the acoustic emission, coupled to the proper acoustic model, in the same fashion as done in hybrid computational approaches. This kind of experimental approach seems to be particularly suited for the study of aerodynamic sound from wall-bounded flows at low Mach number. The main limitation of a PIV-based method in general noise applications is in fact the poor temporal resolution currently available. However, for low enough velocities this is no longer a concern since the resolution is good enough to perform time resolved measurements. Moreover, an experimental technique might be advantageous with respect to computational studies for low Mach number and high Reynolds number flows with immersed solid bodies. The numerical simulation of the flow in the proximity of solid boundaries is in fact particularly complex. In this thesis, a rectangular wall-mounted shallow open cavity has been chosen as a test case, a series of experiments have been performed and different methods and solutions has been tested. In chapter 3 the main details of the experimental setup are given and Curle’s analogy is applied in its classical formulation. In this chapter we also give an estimate of the span-wise coherence of the flow, based on stereoscopic PIV measurements. Both the process of pressure calculation from PIV data and the application of Curle’s analogy are affected by several uncertainties, and simplifying hypotheses is necessary in the process. For this reason we also perform direct microphones measurements of the pressure fluctuations at the walls of the cavity and of the sound emitted. We can therefore compare those values with the estimated quantities from the PIV data in order to validate the results and to check the range of validity of the approach. We find that both the hydrodynamic pressure computed from the PIV data and the sound emission obtained applying Curle’s analogy have a frequency spectrum that is comparable to that of the direct microphones measurements. In section 3.7 we demonstrate that the larger flow structures, responsible for most of the sound, are rather two-dimensional and coherent in the span-wise direction. In chapter 4 we discuss the details of the implementation and solution of both Curle’s Analogy and the theory of vortex sound. In this chapter, in contrast with the implementation of the model performed in chapter 3, we take into account the presence of the non-compact wall in which the cavity is located by using the image principle in the derivation of the solution. The two methods are derived under the assumption of low Mach number and high Reynolds number and for a listener positioned in the far field. The two analogies perform quite well for the present test case and give very similar results, both in total intensity and in the spectral distribution of the emitted sound. In their application, however, they each have different strengths and weaknesses. The two solutions are in fact derived through quite different pathways, and the mathematical schemes used to solve the equations are sensitive to different factors. The choice for either of the two methods needs therefore to be carefully done in relation to the specific application. The use of the image principle seems to be crucial to properly estimate the sound emission for compact geometries placed in large non-compact surfaces. In chapter 5 we investigate the effect of the three-dimensional velocity fluctuations on the final result. We discuss the results obtained by time-resolved thin tomographic PIV measurements. These measurements provided enough velocity vectors in the span-wise direction to allow for the calculation of the differential quantities in that direction and therefore for the computation of the full source terms of both Curle’s analogy and Theory of Vortex Sound. Details about the new experimental setup and measurement technique were given as well. Results showed that the flow is indeed rather two-dimensional and that there is little difference between the analogies source terms computed two or three-dimensionally. Compared to two-dimensional measurements, volumetric PIV measurements are more expensive, require more complex setups and the obtained data requires a much longer processing time. Moreover, the quality of the data is often lower than that of planar PIV. At the same time thin tomographic measurements do not seem to add relevant information to the computation of the sound emission for our experimental case, that is representative of quasi two-dimensional wall-bounded flows where the main source of sound is determined by large span-wise coherent flow structures.