What makes one note higher than another
Pitch is closely related to the frequency of a sound wave: how many vibration cycles occur each second. A simple tone at 440 hertz completes 440 cycles per second, while one at 880 hertz has twice the frequency and is heard an octave higher. Loudness is a different property.
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Faster cycles produce a higher simple tone
Frequency measures how often a repeating vibration completes a cycle. Its unit is the hertz, meaning one cycle per second.
For a simple tone, increasing frequency generally increases perceived pitch. Doubling the frequency gives the interval called an octave, so 440 hertz and 880 hertz are an octave apart.
Pitch is a perception, while frequency is a physical measurement. Complex sounds contain several frequencies, so their perceived pitch can involve more than identifying a single component.
- Frequency describes repetition rate.
- Wave amplitude concerns the size of the disturbance.
- Increasing amplitude does not mean doubling the musical pitch.
A note played softly and then more strongly can retain approximately the same pitch while becoming louder. The vibration rate and the strength of the vibration are separate features.