The measurements of ultrasound velocity and absorption of the aerosil suspensions in nematic liquid crystal (LC) 5CB were carried out in the regime of linear acoustic for the aerosil concentrations of (0-6) volume % and sound frequencies of 1-120 MHz. The sound velocity decreases with the increase of aerosil fraction in the mixture. It shows structuring of aerosil as separated aggregates. Proceeding from the data of absorption in frame of the model of rigid spheres the aggregate parameters (size of aggregates, aggregation rate and volume fraction of aerosil in aggregate) were calculated.