Finite-difference time domain methods are commonly used for acoustics modeling of enclosed geometries. For large spaces and high frequencies, the computational requirements become prohibitive in practical use. Thus, geometric acoustics algorithms are used in those cases. The results of these two classes of algorithm can be combined to model the full acoustic response. To allow direct mixing of the results, the source strengths should be calibrated. This paper derives calibration factors for various finite-difference time domain methods. It is shown that the modelled acoustics responses can then be easily combined to synthesise wide-band hybrid responses.

Synthesizing the room impulse response (RIR) of an arbitrary enclosure may be performed using a number of alternative acoustic modeling methods, each with their own particular advantages and limitations. This article is concerned with obtaining a hybrid RIR derived from both wave and geometric-acoustics based methods, optimized for use across different regions of time or frequency. Consideration is given to how such RIRs can be matched across modeling domains in terms of both amplitude and boundary behavior and the approach is verified using a number of standardised case studies.