Active control of the headpiece of noise barriers

• Published in: The Journal of the Acoustical Society of America 2002-11, Vol.112 (5_Supplement), p.2227-2227
• Main Authors: Möser, Michael, Koh, Hyo-In
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4778814

A theoretical and numerical study of the sound field around an active controlled edge of a noise barrier is described. Studies about noise barrier with passive methods have shown improvement in reduction of the sound level in the range of middle and high frequencies. In this work the sound field on the surface of the headpiece is controlled in such a way that the tangential power transport parallel to their surface is lowered by means of secondary sound sources. First the sound field on the surface of the cylindrical headpiece is locally minimized. The effect of the control position and number of the control point on the sound field near the headpiece and in far field at various frequencies is discussed. The radiated power in the far field of the shadow region is globally minimized, which is the target to reduce, and compared to previous results. Afterwards the method of modal restructing is shown whereby each modal amplitude is controlled individually. Theoretical computations show improved levels in the shadow zone. Optimal active control methods are discussed and a practically oriented simulation is planned.