The spatial structure of particle suspensions changes gradually with the particle concentration or monolayer density, and hence, affects the statistical properties of the transmission fluctuations. The changes of the suspension structure can be traced back to the concentration dependent changes in the structure of particle monolayers by using the layer model. In the present paper, transmission fluctuation signals of radiation through a monolayer of monodisperse, opaque, hard spherical particles are investigated by the autocorrelation technique in the time domain, mathematically expressed in terms of the expectancy of the transmission product (ETP). By changing the autocorrelation time, a transmission fluctuation spectrum is obtained and can be applied to perform particle size analysis. Due to the fact that the ETP and the expectancy of the transmission (ET) are measurable directly from the experiments, the corresponding transmission fluctuation correlation properties are characterized by a transition function, H, which is defined as H = InETP/InET for practical purposes. By using the direct correlation function proposed in a previous paper, the theory of transmission fluctuation spectrometry with the autocorrelation technique (TFS-AC) is extended to high particle concentrations or monolayer densities. In order to observe the effect of the monolayer density on the spatial structure of the monolayer, some numerical simulations are performed on the TFS-AC. Measurements on a flowing suspension of large particles are carried out using a narrow focused beam of the He-Ne laser. The experimental results are found to be in agreement with the theoretical prediction and numerical simulations on the transition function over a wide range of monolayer densities. All of these considerations are based to date on the assumptions of geometrical ray propagation and monodisperse, opaque, hard spheres.