On the application of partial barriers for spinning machine noise control: A theoretical and experimental approach
Noise reduction by barriers is a popular measure for environmental protection in both urban and rural areas. A barrier, which intercepts the direct path of sound from source to receiver, is frequently used to protect noise sensitive receivers from land transportation noise radiating from highways, railway lines, industrial complexes and airports. This consists of interposing a heavy non-porous or porous material or a combination of the two materials in the path of sound propagation. When the transition of sound through the barrier is negligible, the acoustic field in the shadow region is mainly dominated by the sound diffracted around the barrier. The use of barrier is now extensive across Europe, USA, Australia and Japan due to the increasing concern of adverse noise effects on industrial workers. In these countries not only the barriers have been constructed, but also the extensive research on its design and material is being carried out even today (Singal, 2005). Different types of barriers currently in use have widely different shapes, such as normal straight- edged barriers, top-bended barriers, inclined barriers, partially louver barriers and barriers with multiple edges (Li and Wong, 2005). Barriers are employed in two different regions: outdoor and indoor fields. Although the application of this control measure in both fields are the same, but there are different factors, which mainly influence the performance of the barriers. The factors, in which is of importance, have no adverse effects on other region. When studying the performance of barriers, according to the field they are applied in, the researcher should mainly be aware of these factors and then take them part. Without knowing these factors and ignoring their effects on the barrier performance, no reliable results can be taken. Unfortunately, the significant impacts of these factors are usually omitted in many different studies (Redfearn, 1940; Kurze, 1971; Menounou, 2001).