Questions: Note Names and Octaves

Question 1

In scientific pitch notation, what note immediately follows B4?

• A. A5
• B. C4
• C. C5
• D. B5

Answer: (C)

Octave numbers reset at C, not at A. The sequence runs C4, D4, E4, F4, G4, A4, B4, then C5 begins the next octave. Many beginners expect the number to change at A (since A comes first alphabetically), but scientifically the octave boundary is always between B and C.

Question 2

A4 (440 Hz) and A5 (880 Hz) sound identical because they share the same letter name.

• T. True
• F. False

Answer: False

A4 and A5 share a strong perceptual relationship — they blend smoothly and are considered the 'same pitch class' — but they are not identical sounds. A5 is an octave higher, vibrating at twice the frequency. They sound related (a property called octave equivalence) but occupy different registers and are clearly distinguishable.

Question 3

Why does Western music use only seven letter names (A–G) when there are twelve distinct pitches within an octave?

Model answer: The seven letters correspond to the natural notes (the white keys of a piano), which form the basis of the diatonic scale system. The five remaining pitches are named as sharped or flatted versions of the natural notes rather than receiving separate letters.

The diatonic scale — the foundation of Western tonal music — has seven steps per octave, which is why seven letter names suffice as the primary system. The additional five chromatic pitches are treated as alterations of the naturals, keeping the naming system anchored to the diatonic framework.