Electric Motor Noise

There are numerous applications of electric motors and the type of noise produced by each may be very specific to the installation and type of motor. There are a number of reasons why a motor could be perceived as being noisy:

  • The loudness level of the sound
  • Periodic variation of sound pitch due to motor speed variation
  • Non-periodic variation of sound pitch due to motor speed variation
  • Squeaks/scrapes generated by the moving component
  • High frequency motor whine

The primary excitation sources are:

  • Direct radiated sound from the motor
  • Sound generated from internal components such as gear trains, cables, etc.
  • Structure-borne noise generated through the component mounting system or the component housing
  • Sound generated by interference between the moving component and surrounding components/structures

A number of other factors may influence the generation of sound:

  • Load variation on the motor
  • Acoustic isolation of motor
  • Internal design of component geartrains, cables, etc. to minimize load variation
  • Clearance and tolerance of component and surrounding structures
  • Component/motor mounting
  • Motor Speed

Electric motor noise is a complex and broad subject, as such these pages will develop over time. If you have references or applications you would like to be considered then please contact us.

gear types

Gear Noise

Generated by meshing gears due to the vibration caused by failure of the rolling action between the mating teeth due to: Minute imperfections in manufacture of Tooth pitch circle.

airbus a400

Sound Pressure Level

When we measure noise level we normally measure the sound pressure level and express the result as something like 85dB(A)

  • dB is an abbreviation of decibel – the sound pressure scale is vast and so we take the logarithm of the measurement to make the numbers easier to handle
  • A is an abbreviation for A-weighting – a simple filter that is applied to make the measurement more meaningful by by weighting the response to more closely match the human ear

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