Whenever people transport in Star Trek, we hear a distinctive sound which seems to be unique for each Trek series. In-universe, where does this sound come from, what produces it and why is transportation followed by this sound? Answer WARNING: This answer contains speculative conclusions Here is a list of canonically known components of the transporter: Annular confinement beam Biofilter Gravitational compensator Heisenberg compensator Molecular imaging scanner Particle lock Pattern buffer/multiplex pattern buffer Phase discriminator Phase transition coil Primary energizing coil Site-to-site transport interlock Targeting scanner Transporter console List copied from memory alpha First of all we can deduce things, that do not make that sound: Since this sound appears not only in transporter rooms but also on target sites where there is no transporter equipment, we can safely assume that it is not produced by the machinery inside the transporter room. So we're looking for things out...