D[1] is a musical note a whole tone above C, and is known as Re within the fixed-Do solfege system. Its enharmonic equivalents are C (C-double sharp) and E (E-double flat). It is the third semitone of the solfège.
When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of middle D (D4) is approximately 293.665Hz.[2] See pitch for a discussion of historical variations in frequency.
| Scientific designation | Helmholtz designation | Octave name | Frequency (Hz) | |
|---|---|---|---|---|
| D−1 | D͵͵͵ or ͵͵͵D or DDDD | Subsubcontra | ||
| D0 | D͵͵ or ͵͵D or DDD | Subcontra | ||
| D1 | D͵ or ͵D or DD | Contra | ||
| D2 | D | Great | ||
| D3 | d | Small | ||
| D4 | d | One-lined | ||
| D5 | d | Two-lined | ||
| D6 | d | Three-lined | ||
| D7 | d | Four-lined | ||
| D8 | d | Five-lined | ||
| D9 | d | Six-lined | ||
| D10 | d | Seven-lined |