B (musical note)

B, also known as Si, Ti, or, in some European countries, H, is the seventh note of the fixed-Do solfège. Its enharmonic equivalents are C♭ and A𝄪.

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of Middle B (B4) is approximately 493.883 Hz. See pitch (music) for a discussion of historical variations in frequency.

Common scales beginning on B

 * B major: B C♯ D♯ E F♯ G♯ A♯ B
 * B natural minor: B C♯ D E F♯ G A B
 * B Harmonic minor: B C♯ D E F♯ G A♯ B
 * B Melodic minor ascending: B C♯ D E F♯ G♯ A♯ B
 * B melodic minor descending: B A G F♯ E D C♯ B

Diatonic scales

 * B Ionian: B C♯ D♯ E F♯ G♯ A♯ B
 * B Dorian: B C♯ D E F♯ G♯ A B
 * B Phrygian: B C D E F♯ G A B
 * B Lydian: B C♯ D♯ E♯ F♯ G♯ A♯ B
 * B Mixolydian: B C♯ D♯ E F♯ G♯ A B
 * B Aeolian: B C♯ D E F♯ G A B
 * B Locrian: B C D E F G A B

Jazz melodic minor

 * B Ascending melodic minor: B C♯ D E F♯ G♯ A♯ B
 * B Dorian ♭2: B C D E F♯ G♯ A B
 * B Lydian augmented: B C♯ D♯ E♯ F G♯ A♯ B
 * B Lydian dominant: B C♯ D♯ E♯ F♯ G♯ A B
 * B Mixolydian ♭6: B C♯ D♯ E F♯ G A B
 * B Locrian ♮2: B C♯ D E F G A B
 * B Altered: B C D E♭ F G A B

Variation of meaning by geographical region
The referent of the musical note B varies by location. See note for a discussion on other differences in letter naming of the notes.

In the United States, Canada, Australia, the United Kingdom, the Republic of Ireland, and the Netherlands, as described above, B usually refers to the note a semitone below C, while B-flat refers to the note a whole tone below C.

However, in Germany, Central and Eastern Europe, and Scandinavia, the label B is used for what, above, is called B-flat, and the note a semitone below C is called H. This makes possible certain spellings which are otherwise impossible, such as the BACH motif (Wikipedia).