“The name flanging comes from the original method of creation, which involved playing the same recording on two synchronized tape recorders with the output of one machine out of phase as above, and then mixing the two output signals together. As long as the machines are perfectly synchronized, the result will be silence, as the signals will be cancelling each other out. Given the near-impossibility of keeping two analog tape decks perfectly in sync, however, this silence is only achieveable for a split second before the signals slip slowly out of sync again. If the operator places his/her finger on the flange (that is to say, the rim) of one of the tape reels, that machine can be made to slow down, slipping out of sync by tiny degrees. A listener will hear the familiar ‘drainpipe’ swooping effect as shifting sum-and-difference harmonics are created.”