period one
Fundamentals of Sound
notes
One-Third Octave Bands
amplitude
63 125 250 500 1,000 2,000 4,000 8,000
Middle ground between octave-band analysis and full-spectrum analysis is provided by one-third octave-band analysis. One-third octave bands divide the full octaves into thirds. The upper cutoff frequency of each third octave is greater than the lower cutoff frequency by a factor of the cube root of two (approximately 1.2599). If tones are contained in the broadband sound, they will be more readily apparent in the third octaves.
The use of octave bands is usually sufficient for rating the acoustical environment in a given space. One-third octave bands are, however, more useful for product development and troubleshooting acoustical problems.
