Oktavband

Oktavband, in acoustics, is a frequency band that spans one octave, meaning the upper limit of the band is twice its lower limit. This concept is used to describe how sound energy is distributed across different frequency ranges and to summarize a sound’s spectral content in a compact form. In practice, octave-band analysis is commonly implemented with standard sets of adjacent bands.

The most widely used 1-octave bands have center frequencies around 31.5 Hz, 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz. Each band covers frequencies from its center divided by the square root of two to its center multiplied by the square root of two. Standardization bodies, notably IEC 61260, define these bands and the associated measurement procedures. In many applications, octave-band results are also presented in weighted forms, such as A-weighted or C-weighted levels, to reflect human hearing sensitivity.

In addition to 1-octave bands, narrower fractional-octave bands (most commonly 1/3-octave bands) are used when finer spectral resolution is required. Oktavbands are widely applied in environmental noise assessments, architectural and room acoustics, and occupational health to identify frequency ranges that dominate a source, compare different environments, or guide mitigation strategies.

Calculation and implementation typically involve filter banks in measuring instruments or software that decompose a signal into adjacent octave bands. The concept dates from early 20th-century acoustics and has been formalized through international standards to ensure consistency across measurements and reporting.