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An octave band is a frequency band that spans one octave (Play ⓘ).In this context an octave can be a factor of 2 [1] [full citation needed] or a factor of 10 0.301. [2] [full citation needed] [3] [full citation needed] An octave of 1200 cents in musical pitch (a logarithmic unit) corresponds to a frequency ratio of 2 / 1 ≈ 10 0.301.
For example, the frequency one octave above 40 Hz is 80 Hz. The term is derived from the Western musical scale where an octave is a doubling in frequency. [note 1] Specification in terms of octaves is therefore common in audio electronics. Along with the decade, it is a unit used to describe frequency bands or frequency ratios. [1] [2]
An octave is the interval between one musical pitch and another with double or half its frequency. For example, if one note has a frequency of 440 Hz, the note one octave above is at 880 Hz, and the note one octave below is at 220 Hz. The ratio of frequencies of two notes an octave apart is therefore 2:1.
[6] "From this it will be seen that (1) the hum note should be a perfect octave below the strike note; (2) the nominal should be a perfect octave above the strike note; (3) the third above the strike note is a minor 3rd and the fifth perfect; (4) that all these notes should be in perfect tune with each other.
The fourth harmonic vibrates at four times the frequency of the fundamental and sounds a perfect fourth above the third harmonic (two octaves above the fundamental). Double the harmonic number means double the frequency (which sounds an octave higher). An illustration in musical notation of the harmonic series (on C) up to the 20th harmonic.
As a matter of convention, the ITU divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10 n) metres, with corresponding frequency of 3×10 8−n hertz, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name.
Since the dawn of time, rock bands have been giving themselves really stupid names. This was especially true in the 1960s when anyone with 20 hits of acid and a thesaurus could name a band ...
This is a little over 6 dB/octave and is the more usual description given for this roll-off. This can be shown to be so by considering the voltage transfer function, A, of the RC network: [1] = = + Frequency scaling this to ω c = 1/RC = 1 and forming the power ratio gives,