Wow & Flutter
Wow and flutter describe short-term variations in playback speed that modulate pitch.
Wow refers to slower variations and flutter to faster ones. Percentages depend on the measurement method and weighting; weighted RMS and weighted peak results are not directly interchangeable.
Wow & Flutter — Reel-to-Reel
For a reel-to-reel deck, the figure characterizes short-term tape-motion stability at the stated speed and test condition. Sustained tones can make speed modulation easier to notice.
Compare the same speed, weighting and measurement basis. A combined wow-and-flutter result is different from a flutter-only value, and neither specifies the average speed’s accuracy.
Wow & Flutter — Tape Deck
For a cassette deck, the figure describes fluctuations in tape travel through the capstan and tape path under a stated test. Tape and transport conditions influence the result.
Compare identical weighting and RMS or peak conventions, retaining any upper limit. A smaller differently weighted number is not necessarily better, and separate wow or flutter figures should not be presented as a combined measurement.
Wow & Flutter — Turntable
For a turntable, the result describes short-term rotational-speed variation under the stated test method. The test record and measurement arrangement can influence a measured result.
Keep the rotation speed, weighting, RMS or peak convention and any bound with the value. A ± notation is not a span of measured results, and steady speed deviation is a separate property.