Noise levels inside commercial aircraft and automobile impact both the quality of the speech communication between the crew members and the communication between the crew and passengers. Noise measurements are expensive and have significant variability. Therefore, geometrical techniques can be used as an alternative to predict the steady state frequency response or the impulse response. This paper presents a ray-based technique to predict the acoustic response and speech transmissibility indices inside aircraft and auto-mobile. The effect of the background acoustics levels on speech communication is ana-lyzed. Moreover, the effect of the acoustic treatments on the reflected field and its inter-ference with the direct field perceived by the listener is analyzed.
