Sound Design Psychoacoustics and Sound Perception 2 — Questions and Answers
Question 1: Binaural hearing primarily refers to:
- Listening to audio exclusively through headphones
- Using both ears together to localize the direction and distance of sound sources (Correct answer)
- Listening at frequencies above 20kHz using special equipment
- Recording audio with two microphones in a figure-8 polar pattern
Correct answer: Using both ears together to localize the direction and distance of sound sources
Binaural hearing uses both ears and the interaural time and level differences (ITD and ILD) between them to determine the spatial position of sound sources.
Question 2: Head-Related Transfer Functions (HRTFs) describe:
- The frequency response specifications of studio headphones
- How sound is modified by the head, ears, and torso before reaching the eardrums (Correct answer)
- The gain structure of a standard signal processing chain
- Network transfer protocols used for streaming audio data
Correct answer: How sound is modified by the head, ears, and torso before reaching the eardrums
HRTFs are filters characterizing how the outer ear (pinna), head, and torso shape incoming sounds, providing the spatial cues the brain uses to localize sound.
Question 3: The 'cocktail party effect' refers to the auditory system's ability to:
- Tolerate high SPL levels in loud social environments
- Selectively focus on one conversation while filtering out background noise (Correct answer)
- Perceive rhythmic patterns in music at social gatherings
- Adapt the equal loudness response to noisy environments
Correct answer: Selectively focus on one conversation while filtering out background noise
The cocktail party effect describes selective auditory attention — the brain's ability to focus on one voice or instrument among many competing sound sources.
Question 4: What is auditory fatigue?
- Permanent noise-induced hearing loss from chronic loud exposure
- A temporary reduction in hearing sensitivity after exposure to loud sounds (Correct answer)
- The tendency for engineers to make poor mix decisions during long sessions
- The inability to distinguish between harmonically similar sounds
Correct answer: A temporary reduction in hearing sensitivity after exposure to loud sounds
Auditory fatigue is a temporary threshold shift — a reversible reduction in hearing sensitivity caused by sustained loud sound exposure, which recovers with rest.
Question 5: In psychoacoustics, 'critical bandwidth' refers to:
- The maximum bandwidth supported by professional digital audio interfaces
- The frequency range within which two tones interact and mask each other in the cochlea (Correct answer)
- The full range of human hearing from 20Hz to 20kHz
- The bandwidth required for CD-quality audio transmission
Correct answer: The frequency range within which two tones interact and mask each other in the cochlea
Critical bandwidth corresponds to frequency processing regions (critical bands) in the cochlea where tones compete and mask each other perceptually.
Question 6: Which factor does NOT directly affect horizontal sound localization in humans?
- Interaural Time Difference (ITD)
- Interaural Level Difference (ILD)
- The pitch or frequency of the sound (Correct answer)
- Spectral shaping by the outer ear (pinna cues)
Correct answer: The pitch or frequency of the sound
Horizontal localization relies on ITD (timing differences between ears) and ILD (level differences), while spectral pinna cues aid elevation — pitch alone does not determine direction.
Question 7: What is the 'missing fundamental' phenomenon in psychoacoustics?
- When a recording has the low-frequency content accidentally filtered out
- When the brain perceives a fundamental pitch that is not physically present in the signal (Correct answer)
- When reverb masks the fundamental note in a dense mix
- The loss of bass frequencies when playing audio through small speakers
Correct answer: When the brain perceives a fundamental pitch that is not physically present in the signal
The missing fundamental occurs when only the harmonics of a tone are present, yet listeners reliably perceive the pitch of the absent fundamental frequency.
Sound Design Psychoacoustics and Sound Perception 2
Binaural hearing primarily refers to: