Psophometer
In telecommunications, a psophometer is an instrument that measures the perceptible noise of a telephone circuit.<ref name="Hickman, EW, 2001" />
The core of the meter is based on a true RMS voltmeter, which measures the level of the noise signal. This was used for the first psophometers, in the 1930s.<ref name="IEEE, Psophometer" /> As the human-perceived level of noise is more important for telephony than their raw voltage, a modern psophometer incorporates a weighting network to represent this perception.<ref name="Hickman, EW, 2001" /><ref name="IEEE, Psophometer" /><ref name="CCITT, P53" /> The characteristics of the weighting network depend on the type of circuit under investigation, such as whether the circuit is used to normal speech standards (300 Hz – 3.3 kHz), or for high-fidelity broadcast-quality sound (50 Hz – 15 kHz).<ref name="Hickman, EW, 2001" />
EtymologyEdit
The name was coined in the 1930s, on a basis from Template:Langx, itself derived from Template:Langx.<ref name="OED, Psophometer" /> It is unrelated to Template:Langx.
The '-meter' suffix Template:Langx was already widely used in English, but also derives originally from Greek.<ref name="OED, Psophometer" />