Wall pressure fluctuations beneath a turbulent boundary layer in the presence of a mean pressure gradient are investigated in this study. The mean pressure gradient is achieved by changing the ceiling angle of a rectangular channel designed for flow-acoustic measurements. Wall pressure spectra are measured for zero-, adverse-and favorable-pressure-gradient boundary layers by using a pin-hole microphone in conjunction with a high-frequency-calibration procedure. A direct measurement of the wall pressure wavenumber-frequency spectrum Φ pp (k 1 , k 2 , ω) is also performed with the use of a rotating linear antenna of remote microphones. The microphone array has been optimized to improve its response with respect to previous works (Arguillat et al., 2010). Both aerodynamic and acoustic components of the wavenumber-frequency spectrum can thus be identified and are investigated.