Used in the context of filters and equalisers, the term refers to the gradient or steepness of the change in signal amplitude at the turnover frequency. First-order filters have a slope of 6dB/octave, while second-order is 12dB/octave and third-order is 18dB/octave. The steepest slope typically found in audio filters (ususally in synthesizers and loudspeaker crossovers) is 24dB/Octave (fourth-order). Shelf equalisers normally have 6dB/octave slopes.  

In the context of electronic audio equipment, a stage is a functional block of circuitry that performs a specific task. For example, a 'four-stage' phaser effects pedal employs four all-pass filter circuits. An individual stage could be a preamplifier, an insert return buffer, a section of an equaliser, or a mix-bus amplifier, for example, and the process of optimising the signal level passing through each stage is called gain-staging. 

Also known as a Phase-Rotator. An electronic filter circuit that doesn't change the amplitude of any signal passing through it, but which alters the phase of the signal at different frequencies in a non-linear way. Used as a core element of phaser effects pedals, and also in broadcast processors to help make asymmetrical audio signals symmetrical (which allows a slightly higher output level before clipping). 

See All-Pass Filter

Least Significant Bit. In a binary number the bit that carries the smallest multiplier value (units) is deemed the least significant bit, and is typically the right-most digit in a binary number. The three-bit binary equivalent of the decimal number 1 is 001, and the bit showing 1 is the LSB.

Most Significant Bit. In a binary number the bit that carries the largest multiplier value is deemed the most significant bit, and is typically the left-most digit in a binary number. So the three-bit binary equivalent of the decimal number 4 is 100, and the bit showing 1 is the MSB.

A plosive is the strong puff of air from the mouth which is generated when speaking or singing syllables with 'b's or 'p's. if a plosive blast reaches a microphone's diaphragm it can create a large unwanted low-frequency signal and distortion (see Wind-shield).

See Wind-Shield

A mechanical acoustically-transparent screen placed in front of or completely enveloping a microphone to prevent moving air currents from impacting the diaphragm and generating unwanted noise. In studio use a wind-screen is typically used to prevent plosive blasts from vocals or speech reaching the mic diaphragm, and it's typically a large disc made of a two layers of mesh fabric, a perforated metal disc, or an open-cell foam disc. In location sound gathering applications a wind-shield is typically a large fabric-covered frame which completely envelopes the microphone with a volume of still 'dead air'.