High-intensity ultrasound is a technology used to improve the performance of processes in the chemical, pharmaceutical, biomass pretreatment, and food industries. However, few studies were described in the literature to comprehend the acoustic wave propagation in the material and their efficiency in the process. Thus, this study aims to determine the acoustic fields of aqueous biomass solutions from flower stalk banana using the calorimetric method and a determined sonotrode position. These tests were conducted at temperatures from 0 to 60 °C and ultrasound power from 120, 160, to 320 W. Also, the specific heat capacity and density of the solution were determined experimentally as a function of the solution concentration (0.040 to 0.100 g biomass mL−1), pH (3, 5, and 7), and temperature. The position of the thermocouple was maintained at 1 cm from the sonotrode, and the ultrasound frequency was 24 kHz. The methods and results presented in this study can be used to reproduce acoustic field calculations in aqueous biomass solutions, aiming the construction of acoustic processor systems.