Development of a Ray Tracing Computer Model for the Prediction of the Sound Field in Long Enclosures

A Comparison of Different Techniques for Simulating and Measuring Acoustic Parameters in a Place of Worship: Sant Jaume Basílica in Valencia, Spain

“…In Figure 13, when we look at the relative errors of the parameters by frequencywith respect to the corresponding jnd's, we can see that in almost all cases the error is below5jnd units, values which are similar to those obtained by [11] in his study of 11 concert halls, and within the variability shown by the parameters in each hall [15]. This means that the discrepancies between the predicted values and the measured values barely reach 5jnd for all 4possi-ble measurement-simulation combinations, this value being the threshold for what ahearer is able to perceive.The least satisfactory results are for T s .I nt he comparison of the EPIDAURE predicted values with the WinMLS measured values, the relative error is nearly 20 jnd.…”

“…The unsatisfactory results initially obtained [8] due to the loss of the wave nature of the sound signal have been improved, in large part thanks to scatter field techniques which takei nto account the scattering properties of room materials and structures [4,9,10]. Ascertaining the real acoustic properties of the materials making up the room is sometimes difficult [11], and for this reason measuring its scatter coefficients [12,13,14] in the laboratory," in situ", in nonscatter field conditions [15], is the first line of research today [16]. Building very detailed geometric models does not guarantee greater accuracyincalculating the acoustic parameters if the acoustic features (absorption and scattering)o ft he materials used to build the model are not a close enough approximation.…”

An approximate treatment of reflection coefficient in the phased beam tracing method for the simulation of enclosed sound fields at medium frequencies

“…There were some previous works on the determination of receiver size (for example [6][7][8]). Beams should densely cover the space to describe the propagation of spherical wave adequately.…”

The prediction of speech intelligibility in underground stations of rectangular cross section

“…7 This model was then tested using a scale model of a station with curved surfaces, and shown to accurately predict soundpressure levels and early decay times at all frequencies. 5,8 The distinguishing features of this ray-tracing model, which make it appropriate for modeling the sound field in a long enclosure, are described below.…”

“…5,6 Initially a model was developed for the prediction of sound propagation, early decay time, and reverberation time in a long enclosure, using hypothetical spaces to ensure that the characteristics of the sound field in a long, nondiffuse, space were correctly modeled. 7 This model has been validated using data measured in a scale-model underground station. 5,8 This paper describes the further development of the raytracing model to include the prediction of acoustical parameters relating to speech intelligibility, such as clarity index and definition.…”