The best replacement for amplitude is frequency.

The best alternatives to amplitude are rated as following:
★★★★★  frequency
★★★★  magnitude
★★★★  intensity
★★★  period
★★  guitar rig
★★  loudness
★  frequency modulation
★  frequency graph
★  wavelength
★  ampkit
  guitar rig 5
  frequency plot
  displacement
  peak to peak
  single amplitude
  intensity of light
  intensity of sound
  period pendulum
  azimuth
  intensity sound
  wave height

Your alternative for amplitude is not listed? Suggest!
Speaking about amplitude, one probably shouldn't forget about sound.

Other search terms related to amplitude and their ratings are:
★★★★★ sound
★ frequency
You have in mind a companion for amplitude and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of amplitude in all years. Click on graph for more.
amplitude
frequency
magnitude