Boundary Element and Finite Element method's Advanced Techniques available in LMS Virtual Lab code have been applied to simulate the far field acoustic directional characteristics of an Arrayable Loudspeaker's Horn in comparison with the full space far field measured Acoustic Balloon. The horn comprises a 4" dome compression driver, which represents the electroacoustic transducer, an acoustic waveguide and the horn itself. All the measurements were acquired at RCF Laboratory where a two axis fixture enables to collect a full acoustic Balloon overnight. Experimental test and simulated results are compared using AFMG Speaker Lab's Software. The whole simulation model is solved up to high audio frequencies (16 kHz) and does not take into account symmetry planes which would reduce its size. Owing to model complexity Advanced Techniques as BEM/Fast Multipole BEM & FEM/Automatically Matched Layer (AML) methods are used and compared to show their efficiency in solving an otherwise unaffordable problem by means of standard approaches. The horn model (40 cm x 40 cm mouth) is solved in a far field's Balloon grid of virtual microphones. Test far field directivity results show good agreement in the 500 Hz to 20 kHz frequency range on a 1 degree acoustic Balloon positioned at 100 mt from the source, maximum tolerance +/- 5 dB on the average and less over a meridian and the emission angles respectively. Extensive comparison vs frequency and angle has been considered with the aid of Balloon attenuation, polar and off-axis plots. Model validation is reported for both methods. The comparison with the full space far field predicted pressure distribution from experimental test data acquisition shows good agreement in all the frequency range of interest. Moreover, the comparison between the two approaches allows the evaluation of computational advantages of both techniques in this Professional Audio Application.
Arrayable Loudspeaker Horn BEM/FMBEM & FEM/AML Modeling & Analysis
G Miccoli;
2013
Abstract
Boundary Element and Finite Element method's Advanced Techniques available in LMS Virtual Lab code have been applied to simulate the far field acoustic directional characteristics of an Arrayable Loudspeaker's Horn in comparison with the full space far field measured Acoustic Balloon. The horn comprises a 4" dome compression driver, which represents the electroacoustic transducer, an acoustic waveguide and the horn itself. All the measurements were acquired at RCF Laboratory where a two axis fixture enables to collect a full acoustic Balloon overnight. Experimental test and simulated results are compared using AFMG Speaker Lab's Software. The whole simulation model is solved up to high audio frequencies (16 kHz) and does not take into account symmetry planes which would reduce its size. Owing to model complexity Advanced Techniques as BEM/Fast Multipole BEM & FEM/Automatically Matched Layer (AML) methods are used and compared to show their efficiency in solving an otherwise unaffordable problem by means of standard approaches. The horn model (40 cm x 40 cm mouth) is solved in a far field's Balloon grid of virtual microphones. Test far field directivity results show good agreement in the 500 Hz to 20 kHz frequency range on a 1 degree acoustic Balloon positioned at 100 mt from the source, maximum tolerance +/- 5 dB on the average and less over a meridian and the emission angles respectively. Extensive comparison vs frequency and angle has been considered with the aid of Balloon attenuation, polar and off-axis plots. Model validation is reported for both methods. The comparison with the full space far field predicted pressure distribution from experimental test data acquisition shows good agreement in all the frequency range of interest. Moreover, the comparison between the two approaches allows the evaluation of computational advantages of both techniques in this Professional Audio Application.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
