Musical Frequencies
C2
65.41 Hz
Note: C2
Cosmic Octave Color
Derived visible color (521 nm)
Display swatch #44c55f
EstablishedMusical Standard
Evidence Level
Established
Source Count
1
Last Reviewed
March 23, 2026
Directly measured, standardized, or well-supported in mainstream scientific or technical literature.
This entry documents a musical reference or standard. It should be read as an acoustic and musical reference rather than a biological claim.
Review the evidence modelMusical note C in octave 2. Bass to mid range.
Period
15.29 ms
Wavelength
5.24 m
Nearest Note
C2 (0¢)
Claim Type
Musical Standard
Cosmic Octave Color
Derived visible color (521 nm) · #44c55f
Source
Equal temperament tuning system (A4 = 440 Hz)
Sources
Equal Temperament Tuning System
108 atlas references
The twelve-tone equal temperament reference used for note-frequency lookups throughout the atlas.
Standard equal-temperament note table with A4 = 440 Hz.
Harmonic Series
Octave Ladder
Every audible octave of this frequency — the same tone, higher and lower.
Nearby in the Atlas
Entries within ±35 cents of this tone when reduced to the same octave — candidates for pairing or comparison.
C3Musical Frequencies
130.81 Hz-0.1¢
C4Musical Frequencies
261.63 Hz-0.1¢
C5Musical Frequencies
523.25 Hz-0.1¢
C6Musical Frequencies
1.0 kHz-0.1¢
C7Musical Frequencies
2.1 kHz-0.1¢
C8Musical Frequencies
4.2 kHz-0.1¢
musicequal-temperamentoctave-2