CTS Audio Systems and Acoustics

Question 1

A microphone with a cardioid polar pattern is most effective at rejecting sound from which direction relative to the front of the capsule?

Accepted Answer

180 degrees off-axis (rear)

Answer

A cardioid microphone provides maximum rejection directly behind the capsule (180 degrees off-axis). Sensitivity falls off gradually as you move from front (maximum) to sides (–6 dB) to rear (maximum rejection), making it ideal for reducing feedback from monitors placed behind the mic.

Question 2

What does the term 'gain structure' refer to in an audio signal chain?

Accepted Answer

Setting appropriate signal levels at each stage to maximize headroom and minimize noise

Answer

Gain structure is the discipline of setting each device in the signal chain to operate at an optimal level—high enough above the noise floor to maintain signal quality, but with enough headroom below clipping to handle peaks without distortion. Poor gain structure is the leading cause of hum, hiss, and distortion in AV systems.

Question 3

What is the primary purpose of a graphic equalizer in an installed sound system?

Accepted Answer

To correct for room acoustic anomalies and speaker frequency response irregularities

Answer

A graphic equalizer allows the AV technician to cut or boost specific frequency bands, compensating for room modes, reflective surfaces, speaker coloration, and other acoustic issues that cause uneven frequency response at the listener position. It is a key room-tuning tool, not a volume control.

Question 4

Which impedance is the standard load impedance for professional loudspeaker systems driven by a power amplifier?

Accepted Answer

8 ohms (or 4 ohms)

Answer

Professional power amplifiers are designed to drive loudspeaker loads of 4 or 8 ohms. Connecting loads below the rated minimum can overheat or damage the amplifier. 600 ohms is the classic professional line-level impedance standard; 75 ohms is a video/RF coax standard.

Question 5

The 'critical distance' in room acoustics is defined as the point where:

Accepted Answer

The reverberant field level equals the direct sound level

Answer

Critical distance (Dc) is the distance from a sound source at which the direct sound pressure level equals the reverberant field level. Inside the critical distance, direct sound dominates and speech intelligibility is high. Beyond it, reverberant energy dominates, degrading clarity—a key concept for loudspeaker placement in CTS design.

(CTS) Certified Technology Specialist Practice Test

(CTS) Certified Technology Specialist Practice Test

CTS Audio Systems and Acoustics