Characterisation of an airborne sound source for use in a virtual acoustic prototype

Combining Measurement and Modelling in Acoustic Simulation

“…A 'control' sound was then produced by dropping calibrated water droplets of different diameters onto the tray form a fixed height of 1 or 2 meters. The simulated waveforms showed remarkable similarity to those of the real drops [11]. Moreover, the auralised sounds were practically indistinguishable, which of course can be considered the true test of the concept since the aim was to produce a realistic sounding simulation.…”

“…The second example of a VAP is of a rain noise simulator developed at the University of Salford [11] in response to requests from architects wanting to avoid the 'miserable' sound of rain on the roof of new barracks. Again, this gives an example of a design target couched in purely subjective terms which, as mentioned before, is not easily met without some sort of auralisation tool.…”

“…It was then a relatively easy step to auralise the resulting waveform in headphones. In this way the sound of a single simulated raindrop on the skylight could be heard with no real rain being involved at any stage [11].…”

“…At this stage it became clear that in order to produce a realistic sound it was important to use accurate drop size distribution data from actual rain fall. Fortunately such data is available for a wide range of different rainfall types [11]. Thus, the simulator can reproduce the sound of any type of rainfall on the skylight of our building in Salford, including some rainfall types, like monsoon rain, which have never been experienced in that part of the world!…”

“…Other VAPs have been developed using the above general approach, including a refrigerator [5], a washing machine [15,16,17], an air handling unit, a chiller [4], a tumble dryer [18] and several lawnmowers. Considerably more sophistication is required in some of these cases than for those described above to account properly for all significant mechanisms, particularly fluidborne, and structure-borne sound.…”