CEA Audio Engineering Principles 3 — Questions and Answers
Question 1: What is the primary function of a high-pass filter in audio processing?
- Boosts high frequencies above a set point
- Attenuates frequencies below a set cutoff frequency (Correct answer)
- Passes all frequencies equally
- Removes the highest frequencies from a signal
Correct answer: Attenuates frequencies below a set cutoff frequency
A high-pass filter allows high frequencies to pass through while attenuating frequencies below the cutoff point.
Question 2: In acoustics, what is the 'critical distance' in a room?
- The distance at which reverberation time is measured
- The point where direct and reverberant sound fields are equal in level (Correct answer)
- The maximum distance a speaker can cover effectively
- The minimum mic distance to avoid proximity effect
Correct answer: The point where direct and reverberant sound fields are equal in level
Critical distance is where the direct sound level equals the reverberant sound level, beyond which the room acoustics dominate perception.
Question 3: Which compressor parameter controls how quickly the compressor stops reducing gain after the signal falls below the threshold?
- Attack
- Ratio
- Release (Correct answer)
- Knee
Correct answer: Release
Release time determines how fast the compressor returns to unity gain after the signal drops below the threshold.
Question 4: What does the term 'latency' refer to in digital audio production?
- The noise floor of a digital system
- The delay introduced by analog-to-digital and digital-to-analog conversion and processing (Correct answer)
- The frequency response curve of an audio interface
- The dynamic range of a digital recording
Correct answer: The delay introduced by analog-to-digital and digital-to-analog conversion and processing
Latency is the time delay that occurs as audio passes through digital conversion and processing, critical to manage in real-time recording scenarios.
Question 5: What is Fletcher-Munson (equal-loudness) curves used to describe?
- The frequency response of microphones at different distances
- The variation in human hearing sensitivity across frequencies at different loudness levels (Correct answer)
- Speaker directivity at different frequencies
- The rolloff characteristics of audio filters
Correct answer: The variation in human hearing sensitivity across frequencies at different loudness levels
Fletcher-Munson curves show that human hearing is less sensitive to low and high frequencies at lower listening levels compared to midrange.
Question 6: In a balanced audio connection, how is noise rejection achieved?
- By using heavier shielding around a single conductor
- By carrying the signal on two conductors in opposite polarity and subtracting them at the destination (Correct answer)
- By doubling the signal voltage on a single conductor
- By grounding both signal conductors
Correct answer: By carrying the signal on two conductors in opposite polarity and subtracting them at the destination
Balanced lines carry equal and opposite signals; any interference affects both equally, and the differential receiver subtracts them, canceling the noise.
Question 7: What is acoustic absorption coefficient, and a value of 1.0 represents what?
- Total reflection of sound energy
- 50% absorption of incident sound energy
- Total absorption of incident sound energy (Correct answer)
- Doubling of incident sound energy
Correct answer: Total absorption of incident sound energy
Absorption coefficient ranges from 0 (perfect reflector) to 1.0 (perfect absorber), with 1.0 meaning all incident sound energy is absorbed.
CEA Audio Engineering Principles 3
What is the primary function of a high-pass filter in audio processing?