D♭ (musical note)
D (D-flat) is a musical note lying a diatonic semitone above C and a chromatic semitone below D. It is thus enharmonic to C. In the French solfège it is known as re bémol. When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of middle D (or D) is approximately 277.183 Hz. See pitch (music) for a discussion of historical variations in frequency.