Arcelik A. S, Product Develop. Dept., Cayirova-41460, Istanbul, Turkey
The aim of these studies was to keep the machine within the 50-dBA range to be competitive within the market. In order to achieve the ultimate goal of noise reduction, measurement methodology evolved on the basis of four steps. Source identification studies have led one to consider that the tub of the machine was driven to act as a loudspeaker because of permanent splashes of the sprayed waters and transmitted vibration of the motor housing, which was located over the tub. Studies have been focused around the elimination of high-frequency water noises and torsional noises of the motor that were dominant around the line frequency and double-line frequency and had a tendency to coincide with the natural frequency of the tub. Achievement of the proposed noise levels has led to studies of new treatment methods to keep the machine within the ranges of acceptable noise quality.