Trane TRG-TRC007-EN Octave-BandRating Method, Sound Perception and Rating Methods, period two

period two

Sound Perception and Rating Methods

notes

Octave-Band Rating Method

octave	center	equipment	sound pressure
		sound power	in the space
band	frequency (Hz)	(dB ref 10-12W)	(dB ref 20 mPa)
1	63	103	63
2	125	104	52
3	250	100	45
4	500	101	38
5	1,000	98	31
6	2,000	93	24
7	4,000	88	16
8	8,000	85	10

Figure 32

Octave-Band Rating Method

A more useful method of rating sound level is to use the octave bands discussed earlier. While octave-band data is not as simple to interpret as a single-number rating, it provides much more information about the character of the sound.

Both sound-power levels and sound-pressure levels can be presented in octave-band format. When equipment sound data is provided in terms of sound-power level in each octave band, an “apples to apples” comparison can be made between various pieces of equipment. In addition, this sound- power data can be converted to sound-pressure levels when the details of the environment are known. This type of analysis will be discussed further in Period Three.

Sound-pressure levels in each octave band, whether predicted from sound- power data or measured in an existing environment, reveal much more about the character of sound than any of the single-number rating methods. It is important to note that any of the single-number ratings described in this section can be calculated from octave-band sound-pressure data. However, octave- band data cannot be derived from any of the single-number ratings.

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