AVIXA CTS-D: PAG-NAG QUESTIONS & ANSWERS SCORED A+

EAD, Equivalent Acoustic Distance - Is the farthest distance one can go from the source without the need for sound amplification or reinforcement to maintain good speech intelligibility. It is a design parameter dependent on the level of the presenter and the noise level in the room PAG - Potential Acoustic Gain is the potential gain that can be delivered by the sound system without ringing and before feedback occurs. It is based upon the number of open microphones, and the distances between source(s) (like a presenter) and microphone(s), microphones to loudspeakers, and listeners to loudspeakers. NAG - Needed Acoustic Gain is to determine how much gain is needed to deliver the same level of sound to all the listeners in the space Is the gain the sound system requires to achieve an equivalent acoustic level at the farthest listener equal to what the nearest listener would hear without sound reinforcement Excessive background noise level will cause this to decrease. Rule of Thumb for EAD for Voice - 4 ft (1.2 meters) is often a safe bet for voice. This assumes a 25 dB acoustic signal-to-noise ratio Gain - Refers to the electronic amplification of a signal. NAG Formula - 20 log (D0 / EAD) in dB, and it indicates the amount of acoustical loss from the EAD position to the farthest listener.Where: D0 = Distance from source to listener EAD = Equivalent Acoustic Distance Calculated before equipment is employed, no equipment is represented in the formula. PAG Formula - 20 log [(D0 * D1 ) / (D2 * DS )] Where: D0 = Distance from source to listener D1 = Distance from loudspeaker to mic D2 = Distance from loudspeaker to listener DS = Distance from source to microphone Assumes that you are using an omnidirectional microphone and loudspeaker. NOM - Number of Open Microphones The more open microphones that are present, the more system gain increases. Open microphones will add together, which increases acoustic power. Each time the number of open microphones is doubled (1 to 2, 2 to 4, etc), acoustic power is doubled. However, each time the number of open microphones is doubled, there is a 3 dB loss before feedback.