Psophometric voltage is a circuit noise voltage measured with a psophometer that includes a CCIF-1951 weighting network. Psophometric voltage is a circuit noise voltage measured with a psophometer that includes a CCIF-1951 weighting network. 'Psophometric voltage' should not be confused with 'psophometric emf,' i.e., the emf in a generator or line with 600 Ω internal resistance. For practical purposes, the psophometric emf is twice the corresponding psophometric voltage. Psophometric voltage readings, V, in millivolts, are commonly converted to dBm(psoph) by dBm(psoph) = 20 log10V – 57.78.