An Acoustical Survey Test at a Petrochemical plant was a complex yet fun challenge. The typical means of performing an acoustical survey test using a standard sound level meter (SLM) is to collect several acoustic measurements in close proximity to the equipment within a space or facility, then analyzing the data to create a “sound map” that shows the acoustical intensity as a function of location within the space or facility. When there are numerous sound sources, the use of an SLM to create the sound map becomes time-consuming and cumbersome. An acoustical camera combines acoustical beamforming technology with real-time video and audio, which enables us to “see” sound in the same manner that a thermal camera enables one to “see” heat. By simply scanning numerous pieces of equipment with the acoustic camera, we can quickly and conclusively identify the loudest pieces of equipment and determine how noise from this equipment propagates. This allows us to perform an acoustical survey in a matter of minutes, as opposed to using a standard SLM, which would require several hours or days to perform. Once the loudest equipment is identified, it is possible to use the SLM to obtain more detailed acoustical measurements, which would aid in the development of an optimum noise attenuation solution.
The attached MP4 files illustrates the usefulness of the acoustic camera when used at a petrochemical plant with numerous loud noise sources. From a height of about five stories, the acoustic camera was scanned across several pieces of equipment. The fundamental low frequency “droning” noise (about 500 Hz) originates from a set of roots blowers behind the building. As shown, when the acoustic camera is scanned towards air compressors, where a high frequency whistle (at about 6000 Hz) can be heard. From about a quarter mile away, the acoustic camera can “hear” steam leaks from pipes at the nearby refinery, and differentiate that noise from other equipment. The acoustic camera enables us to identify the specific sources of noise and the frequency ranges of these noises so that optimum and cost-effective noise attenuation solutions can be developed.