**Frequency**= the number of cycles per TIME

Wave Number = the number of cycles per SPACE

*- [Nikola Tesla]*

**Frequency**alone in reality does not mean anything, except when an undisturbed harmonic oscillation is considered.- 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*(Field of Rotating Machinery Measurment, Monitoring and Analysis)

**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."**Click Here to Calculate Music Intervals in any Octave**

See Also

**convert frequency to wavelength**

**convert wavelength to Frequency**

**Frequency Modulation**

**Frequency Response**

**Oscillation**

**Vibration**

**Wave**

**Wave Field**

**1.20 - Evolution and Devolution of Frequency**

**15.20 - Dissociation Frequency**