CEA CEA Signal Processing & Electronics 1 — Questions and Answers
Question 1: What does a compressor's 'attack time' control in audio signal processing?
- How quickly gain reduction begins after the signal exceeds the threshold (Correct answer)
- The speed at which the output volume increases
- The frequency range affected by compression
- The ratio of input to output signal level
Correct answer: How quickly gain reduction begins after the signal exceeds the threshold
Attack time determines how rapidly the compressor responds and begins reducing gain once the input signal surpasses the set threshold.
Question 2: In a balanced audio circuit, what is the primary benefit of using a differential amplifier at the input?
- Doubles the output impedance
- Rejects common-mode noise picked up along the cable (Correct answer)
- Increases the signal frequency range
- Reduces the need for shielding
Correct answer: Rejects common-mode noise picked up along the cable
A differential amplifier amplifies the difference between the two conductors while canceling identical (common-mode) noise present on both, which is the core principle of balanced audio.
Question 3: What is the purpose of dithering when reducing bit depth in digital audio?
- To increase sample rate
- To add low-level noise that masks quantization distortion (Correct answer)
- To apply dynamic compression
- To synchronize multiple audio streams
Correct answer: To add low-level noise that masks quantization distortion
Dithering adds a carefully shaped low-level noise signal before truncating bit depth, which randomizes quantization errors and prevents audible harmonic distortion.
Question 4: Which filter type passes frequencies below its cutoff point while attenuating higher frequencies?
- High-pass filter
- Band-pass filter
- Low-pass filter (Correct answer)
- Notch filter
Correct answer: Low-pass filter
A low-pass filter allows low frequencies to pass through while progressively reducing the amplitude of frequencies above the cutoff frequency.
Question 5: What does 'Total Harmonic Distortion' (THD) measure in audio electronics?
- The ratio of loudest to softest signals a device can handle
- The level of unwanted harmonic frequencies generated relative to the fundamental (Correct answer)
- The frequency response deviation from flat
- The noise floor of a device
Correct answer: The level of unwanted harmonic frequencies generated relative to the fundamental
THD expresses the combined amplitude of all harmonic distortion products as a percentage of the original fundamental signal level.
Question 6: In audio, what does a limiter's 'brick wall' setting refer to?
- A filter that blocks all frequencies above 20 kHz
- A very high compression ratio (typically 10:1 or greater) that prevents signals from exceeding a set ceiling (Correct answer)
- A hardware safety device that cuts power at high SPL
- An analog circuit that clips waveforms symmetrically
Correct answer: A very high compression ratio (typically 10:1 or greater) that prevents signals from exceeding a set ceiling
A brick wall limiter applies an extreme compression ratio so that the output signal cannot exceed the threshold ceiling regardless of input level.
CEA CEA Signal Processing & Electronics 1
What does a compressor's 'attack time' control in audio signal processing?