טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentFindling-Eldar Odin
SubjectThe Influence of Activ Sound Control Unit on Penetration
of a Single Frequency Component through an Opening
in an Enclosure
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Giora Rosenhouse


Abstract

 The acoustic treatment of environmental noise becomes, in recent years, an important element in improvement of the standards of living. The conventional approach is focused mainly on passive acoustic solutions. This approach is very limited in attenuating low frequencies and giving a good acoustic isolation against noise when openings, such as open windows, ventilation and so on, are required. In the present research, a new approach based on active noise control was investigated. The main advantages of this approach are the ability to cope and overcome difficulties that the traditional passive control cannot and to become complementary to the passive control. The thesis presented here introduced a new acoustic model to reduce and isolate noise penetrating through openings in and out of buildings. We developed an adjusted mathematical model and numerical solution and developed computer programs simulating the ANC system. This model is built in order to analyze the parameters effect on the efficiency of active noise control model and introduce a new method for a geometrical and optimal design of an active control system. In the research we run numerous simulations in order to illustrate the sensitivity of the system and the physical phenomena due to the geometrical design. It was found that the number and the location of the sensors and the secondary and primary sources have a crucial impact on the system performance. An arbitrary emplacement of the system elements without a profound analysis may result in an erroneous effect and deteriorated performance as far as to escalate the initial noise. We introduced the conclusions and the proofs regarding implementation of effective ANC systems on windows and an optimal design of the system using a computer program that calculates the optimal location of the sensors. The importance of the research lies in its original approach to the urban noise problem, treated using active control systems at the penetration point to the building, which allows minimal acoustic treatment at the acoustic sensitive locations and generalization of the acoustic solution regardless of the reduction destination.