Tham khảo tài liệu 'power plant acoustics episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TM 5-805-9 AFM 88-201NAVFAC CHAPTER 2 SOUND ANALYSIS PROCEDURE 2-1. Contents of chapter. This chapter summarizes the four basic steps for evaluating and solving an engine noise problem. The steps involve sound level data for the source sound and vibration criteria for inhabited spaces the fundamentals of sound travel both indoors and outdoors and knowledge and use of sound and vibration treatments to bring the equipment into conformance with the criteria conditions applicable to the work spaces and neighboring areas. Much of this material is discussed in detail in the N V manual but brief summaries of the key items are listed and reviewed here. Special noise- and vibration-control treatments beyond the normal uses of walls structures and absorption materials to contain and absorb the noise are discussed in chapter 3 and examples of the analysis procedure are given in chapter 4. 2-2. General procedure. In its simplest form there are four basic steps to evaluating and solving a noise problem. Step 1 requires the estimation or determination of the noise levels produced by a noise source at the particular point of interest on the initial assumption that no special acoustic treatment is used or required. Step 2 requires the establishment of a noise level criterion considered applicable for the particular point of interest. Step 3 consists of determining the amount of excess noise or the required noise reduction for the problem. This reduction is simply the algebraic difference in decibels between the noise levels produced by the equipment step 1 above and the criterion levels desired for the region of interest step 2 above . Step 4 involves the design or selection of the acoustic treatment or the architectural structure that will provide the required noise reduction step 3 above . This basic procedure is carried out for each octave frequency band for each noise source if there are several sources for each noise path if there are several possible paths and for .
