HELMHOLTZ RESONATOR GEOMETRIC OPTIMIZATION BASED ON CO-PLANAR CONFIGURATION FOR LOW FREQUENCIES NOISE ABSORPTION

• Main Author: I.G. SIREGAR, SREFANI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31042
• Institution: Institut Teknologi Bandung

As known before, reducing noise level in public space, such as public park, public transportations or hospital’s waiting room, could improve community’s quality of life and social health. Therefore, invention in methods and developement in the capacity of noise control is crucial in the midst of various noise type and characteristic with all of limitations of its implementations found today. These issues encourage some development of new methods, aimed at finding new approaces as well as optimization from conventional approaces, for instance, through geometry optimization and by using some new material <br /> <br /> One of the specific use of this noice control system is a kind of effort to improve acoustic performance and quality in a room. Some obstacles that still become a problem for a long time, yet still is one of an interesting object to study from room acoustic concerns is controlling noise in the range of low frequencies. One of the common method to overcome this problem is by using Helmholtz resonator. From the implementation side, the use of Helmholtz resonator is quite successful. But still, conventional Helmholtz resonator needs one fourth of the lenght of the wave in its working frequency as the fair thickness of its air cavity. This is the reason why this method needs a lot of space to work properly. <br /> <br /> This research aims on designing optimized geometry for Helmholtz resonators by using coplanar concept to reduce its needed space when implemented in rooms. Experimental investigation was carried out to obtain the characteristic absorption. It is expected that by using the new geometry and configuration of this material, resonator obtained can work well in the same frequency range, and be more applicable to use in rooms, specially for application in small rooms. <br /> <br /> Samples that used in this experiment was made from PLA (Poly Lactic Acid) and perforated plate made from aluminium. Designs of the sample were made with a three dimentional modelling software, Autodesk Inventor and Solidwork. Meanwhile, the experiment on all samples were implemented by BSWA impedance tube, using transfer function method. <br /> <br /> From the experiment can be concluded that by modifying the neck and air cavity dimension and configuration of the Helmholtz resonator, its operating frequency can be kept in the same value range. Thus, by modified the shape of its air cavity by using coplanar principles the need for air cavities thickness, that must be measured as ¼ wavelength of sound wave in the conventional form, can be reduced up to 15% from its original thickness, in order to obtain the minimum thickness of the Helmholtz resonator, which considered to be more applicable in its use.