CEA Live Sound & Event Production Flashcards

What is 'latency' in the context of digital live sound systems, and why is it a concern?

Answer: The processing delay introduced by digital consoles and signal processors, which can cause comb filtering when combined with direct stage sound

Digital processing introduces a measurable time delay; when this delayed PA signal combines with the direct acoustic sound from stage, it can cause phase cancellation and comb filtering in the near-stage area.

In live sound, what is the role of a 'system engineer' or 'system tech' as distinct from the FOH mix engineer?

Answer: The system engineer designs, tunes, and optimizes the PA system so it sounds consistent throughout the venue, then hands it off to the mix engineer

A system engineer focuses on the technical performance and tuning of the loudspeaker system — coverage, time alignment, EQ — to create an optimized, consistent platform for the mix engineer.

What is 'virtual soundcheck' in modern digital live audio production?

Answer: Playing back a multitrack recording through a digital console to tune the PA and rehearse mixes without requiring the live performers on stage

Virtual soundcheck feeds a previously recorded multitrack of the same show into the console, allowing engineers to tune the system and build mixes at any time without the band present.

What is the 'Haas effect' and how is it relevant to live sound reinforcement?

Answer: The psychoacoustic phenomenon where a sound arriving within approximately 35 ms of a louder sound is perceived as coming from the direction of the first-arriving source

The Haas (precedence) effect means that even if a delay speaker is louder, listeners perceive sound as coming from the direction it first arrives, which is exploited in delay speaker alignment to maintain the illusion that sound comes from the stage.

What does 'RF coordination' involve in a large live event with multiple wireless systems?

Answer: Planning and assigning wireless microphone and IEM frequencies to avoid intermodulation and interference between systems and local TV/broadcast transmitters

RF coordination uses spectrum analysis and intermodulation calculation software to assign clean, compatible frequencies to every wireless microphone and IEM system, avoiding conflicts with each other and local broadcast signals.

In live sound, what is 'gain structure' and why is it important?

Answer: The systematic management of signal levels through each stage of the audio chain to maximize signal-to-noise ratio while preventing clipping

Proper gain structure sets appropriate levels at each stage — preamp, channel insert, bus, amplifier — ensuring the signal is well above the noise floor but never causes any stage to clip.