Real-Time Sound Intensity Measurements

Fig, i. Reel-time digital intensity enslyeer The introduction at rest time analysis using dlgllll Illterlng techniques tor the processing at signals lroln two closely spaced microphones has given a leap terward In the precision with which acoustic Intensity measurements may be carried out.The use at digital litters hoe Increased the possible lreouency range and practically ellmlneteo the Inherent tacit at real time capabilIty associated with FFT anelysls oi the continu-Ing but time veryan signals moat otten encountered lh scaustlce A llit octave digital tlltar system Is shown In Fig.1.The signals Irern the two microphones ere Ireduency analysed In parallel In real time and the sum and the dIIIerence el the two signals Ior each lremency hand are calculated.The omerenee to Integrated over time and divided by the distance between the microphones at the probe to yield the particle velocity V,.The sumv and thus the pressure corresponding to a Point mid« way between the two microphones.Ia than multiplied