###### Abstract
This is likely to alter the airfoil self-noise emission processes, especially for what concerns its TE noise component, which is known to be extremely sensitive to the incoming flow (overall loading, separation/recirculation bubble location, etc.). Aside from that, the flow quality may also be altered by other phenomena, such as low-frequency pressure fluctuations (or \"pumping\" effects), which are inherent to open-jet wind tunnels. Last but not least, open jets are likely to alter the far-field noise radiation, due to both acoustic refraction (by the jet shear layers [28]) and acoustic diffusion (by the jet fine scale turbulence). Although these effects can be corrected a posteriori through analytical and/or semi-empirical means [29; 30; 31; 32; 33], such corrections imply some restrictive assumptions that make them partly conclusive only [25] (e.g., the plug flow model by [PERSON] [29; 30]). All these reasons explain why some researchers explored the use of closed-vein wind tunnels for conducting aeroacoustics experiments [34], including several studies focusing specifically on airfoil TE noise [6; 7; 9; 10; 11; 12; 13; 14]. Following that, the model is placed within a closed-vein test section whose walls are then equipped with flush-mounted microphones so as to measure the noise signature. The latter is expected to be closer to what happens in reality, since the closed-vein ensures a flow that is similar to those obtained in real conditions (as well as in computations). Only the confinement effects need to be handled, whether they relate to aerodynamics (blockage effects) or acoustics (reverberation effects). Concerning blockage effects, they are not deemed to be too problematic, since airfoil TE noise experiments are usually performed for reduced values of flow speed and/or incidence [1]. For instance, the LBL-TE noise is known to primarily emerge at low to moderate Reynolds numbers, which implies a small airfoil chord and/or a low flow speed. In addition, it is also known that LBL-TE noise is generated when the flow is laminar over most of the airfoil' surface, which requires the incidence to be kept small enough, namely, below the stall angle. All in all, one can thus expect blockage effects to be rather minimal for an airfoil TE noise experiment that would be conducted in a closed-vein wind tunnel. Regarding reverberation effects, one option is to cover the test section hard-walls with noise absorbing materials [6; 11] or to replace them with as-like anechoic panels(Kevlar) [12; 13]. This, however, requires to re-design part of the wind tunnel, which may raise practical challenges - from simply modifying its walls up to surrounding it by an anechoic environment. Furthermore, this also raises fundamental questions, e.g., how to properly design acoustic liners and/or deal with their potential issues [35] when the latter are to be exposed to grazing flows, how to mitigate the relative flow alteration [13], acoustic transmission losses [13] and/or background noise exacerbation [36] incurred by Kevlar panels, etc. Another, simpler, option would be to keep the hard-wall wind tunnel as is, while accounting properly for its reverberation effects. This, for instance, is commonly achieved when performing noise source localization using acoustic holography techniques within reverberant environments [37; 38; 39]. There, specific post-processing techniques are employed, which allow de-biasing the localization results from all reverberation effects induced by the vein. In the present case, such de-biasing could be achieved a posteriori by correcting the noise measurements from all reverberation biases, or they could rather be conducted a priori by flush-mounting the microphone(s) where these biases are less. This however requires the reverberation effects to be characterized, both qualitatively and quantitatively.