440
Standard tuning frequency
Four-forty typically refers to a frequency or pitch—specifically, 440 hertz, the standard tuning reference for musical instruments.
When musicians tune to A440, they're calibrating the note A above middle C to vibrate at 440 cycles per second.
The number also designates a quarter-mile race or track in athletics, though this usage has faded as metric measurements replaced imperial.
Highest academic mark
- tuningAdjusting pitch accuracy
- standardLevel of quality accepted
- hertzFrequency measurement unit
- tuning forkVibrating standard for pitch
reference · concert pitch · international standard · diapason · pitch pipe · calibration · intonation · temperament
Frequency measurement unit
- wavesTraveling energy disturbances
- vibrationRapid oscillating movement
- oscillationRepeated back-and-forth movement
- resonanceAmplified oscillation at natural frequency
amplitude · wavelength · cycles per second · sound wave · audio frequency · sine wave · waveform · spectrum
A
Highest academic mark
tuning fork · reference · concert pitch · international standard · diapason · pitch pipe · calibration · intonation · temperament · equal temperament
hertz
Frequency measurement unit
- wavesTraveling energy disturbances
- vibrationRapid oscillating movement
- oscillationRepeated back-and-forth movement
resonance · amplitude · wavelength · cycles per second · sound wave · audio frequency · sine wave · waveform · spectrum · bandwidth
440subsonic
Below sound's speed
infrasound · middle C · ultrasound · ultrasonic · silence