Brooks QS 70 Echo

1) One distinct repeat of a sound because of the sound reflecting off a surface.
2) Loosely, used to mean reverberation (the continuing of a sound after the source stops emitting it, caused by many discrete echoes closely spaced in time).

Cut-Off Frequency (Turnover Frequency)
1) The highest or lowest frequency in the pass band of a filter.
2) The highest or lowest frequency passed by an audio device (the cut-off frequency is usually considered to be the first frequency to be 3 dB lower than a reference frequency in the middle of the bandwidth of the device)

Brooks M 44 Headroom
1) The level difference (in dB) between normal operating level and clipping level in an amplifier or audio device.
2) A similar level difference between normal tape operating level and the level where the distortion would be 3%.
3) The difference, in decibels, between the peak and RMS levels in program material.

In
Short For "in the circuit," in other words "active."

Brooks Cinema NZ 60 Acoustic Echo Chamber
A room designed with very hard, non-parallel surfaces and equipped with a speaker and microphone; dry signals from the console are fed to the speaker and the microphone will have a reverberation of these signals that can be mixed in with the dry signals at the console.

Leakage
Sounds from other instruments and sources that were not intended to be picked up by the microphone.

Consumer Format (Consumer DIF)
A standard adopted by IEC for sending and receiving digital audio based on The AES Professional Interface.

Console
A set of controls and their housing, which control all signals necessary for recording and mixing.