: The Helmholtz resonator is a cavity in which an acoustic wave is created by a vortex shedding at its edge. The specifications of this wave depend on various parameters such as cavity geometry and main flow velocity. In the present study, in order to maximize pressure fluctuations, the pressure fluctuations were measured and discussed at different velocities by changing the geometry of the cavity. These studies include the effect of opening width and depth of cavity on the vortex shedding, acoustic wave, intensification frequencies and the amplitude of pressure fluctuations. In the following, two auxiliary cavities were used to strengthen the pressure fluctuations in the cavity and the pressure fluctuations were received in the two conditions with small and large distances. After examining the parameters of the cavity and using the auxiliary cavities, the appropriate width of the opening was designed and created for two specific velocities, and the pressure fluctuations were measured. A number of rectangular cavities with different dimensions were designed, made and connected to the wall of the wind tunnel to measure the pressure fluctuations. The pressure fluctuations were measured at the end of the cavity using the pressure sensors for a period of time. Eventually, the results were transferred to the frequency field using a Matlab code and Fast Fourier Transform to obtain the dominant frequencies of the cavity and the amplitude of the corresponding oscillations. The results showed that as the vortex shedding frequency reaches different acoustic frequency modes, an intensification happens and the amplitude of the oscillations suddenly increases. The amplitude of the oscillations decreases in the intensified state as the depth of the cavity increases, and it occurs at the lower frequencies, due to acoustic attenuation. In addition, placing auxiliary cavities close to the main cavities strengthens the pressure fluctuations in both auxiliary and main cavities. In the following, with the aim of improving the flow structure and intensifying the fluctuations frequency at low velocities, a plannar time resolved PIV measurement was used to investigate the effect of edge creation in three different modes. In order to use the PIV technique, a seeding mechanism was designed and made and olive oil was injected into the main stream of a suction wind tunnel as the tracer particles.In the following, the vortex shedding into the cavity, was captured in different modes and the required results were extracted using image processing. The results demonstrated that by placing the edge in the opening of the cavity and shrinking it, the irregular flow in the opening of the cavity changes to a harmonic structure and a regular vortex shedding fell out. Also, the vortex shedding frequency and the power of the incoming vortex will increase by reducing the width of the opening of the cavity. The infiltration of the vortex into the cavity will increase and will occupy more space in the throat. Keywords: Helmholtz Resonator, Deep Cavity, Pressure Fluctuations, Hydrodynamic Modes, Acoustic Modes, PIV Technique