Trane TRG-TRC007-EN manual Near Field

period four

Equipment Sound Rating

notes

Near Field

near field

source

Figure 56

The near field is an area adjacent to the source where sound does not behave as it would in a free field. Most sound sources, including all HVAC equipment, do not radiate sound in perfectly spherical waves. This is due to the irregular shape of the equipment and different magnitudes of sounds radiating from the various surfaces of the equipment. These irregularities cause pressure-wave interactions that make the behavior of the sound waves unpredictable.

Sound-pressure measurements should not, therefore, be made in the near field. The size of the near field is dependent on the type of source and dimensions of the equipment.

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