Psophometer

In telecommunications, a psophometer is an instrument that measures the perceptible noise of a telephone circuit.

[1] The core of the meter is based on a true RMS voltmeter, which measures the level of the noise signal.

[2] 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.

[1][2][3] 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).

[1] The name was coined in the 1930s, on a basis from Ancient Greek: ψόφος, romanized: psóphos, lit.