**Frequency** = the number of cycles per

TIME
Wave Number = the number of cycles per

SPACE
**Frequency** alone in reality does not mean anything, except when an undisturbed harmonic oscillation is considered.” -

Nikola Tesla
- Number of cycles per unit time. SI unit: hertz, Hz (cycles/s). (Applied Spectroscopy, Vol. 29, #1, 1975)
- The number of vibrations per second?; expressed in hertz (Hz). (The Science of Sound)
- Rate at which a waveform repeats. Expressed in cycles per second? or Hertz (Hz). (Learning Music with Synthesizers)
- The number of cyclical variations per unit time.
**Frequency** is generally expressed in Hertz (Hz) also denoted cycles per second (cps). (Compendium of Noise Engineering - Part I)

*"The repetition rate of a periodic vibration within a unit time. This is normally expressed in units of cycles per minute (cpm), events per minute (epm), or cycles per second (cps or Hz). It can be expressed relative to shaft rotative speed. With respect to rotating machinery vibrations, there are two types of frequencies of interest: A) the shaft rotative ***frequency**, and B) the various vibration frequencies as measured by vibration transducers. Rotative **frequency** is usually expressed in terms of rpm. Vibration frequencies are commonly expressed in terms of a fraction or percentage of the shaft rotative **frequency**: 1X means one times rotative **frequency**, 2X means two times, 1/2X, or 50 percent, means one-half times, etc." (Field of Rotating Machinery Measurment, Monitoring and Analysis)

**Click Here to Calculate Music Intervals in any Octave**
See Also

**1.20 - Evolution and Devolution of Frequency**
**15.20 - Dissociation Frequency**
**Frequency Modulation**
**Frequency Response**
**Oscillation**
**Vibration**
**Wave**
**Wave Field**