Sound Design Waves And Sound 2 — Questions and Answers
Question 1: What happens to the wavelength of a sound wave when its frequency doubles while traveling through the same medium?
- It doubles
- It halves (Correct answer)
- It stays the same
- It quadruples
Correct answer: It halves
Wavelength and frequency are inversely proportional (λ = v/f), so doubling frequency halves the wavelength.
Question 2: Which type of wave interference produces a standing wave pattern in a closed pipe?
- Destructive interference only
- Constructive interference only
- A combination of incident and reflected waves (Correct answer)
- Random phase interference
Correct answer: A combination of incident and reflected waves
Standing waves in closed pipes form when the incident wave combines with its reflection, creating fixed nodes and antinodes.
Question 3: The speed of sound in air increases when which condition changes?
- Air pressure decreases
- Humidity decreases
- Temperature increases (Correct answer)
- Density increases
Correct answer: Temperature increases
Higher air temperature increases molecular kinetic energy, allowing sound to travel faster through the medium.
Question 4: A sound designer notices that a room has a resonant 'boom' at 80 Hz. What is the most likely cause?
- High-frequency reflection
- A room mode caused by room dimensions (Correct answer)
- Speaker distortion at low frequencies
- Excessive reverberation time
Correct answer: A room mode caused by room dimensions
Room modes occur when room dimensions create standing waves at specific frequencies, causing resonant buildup.
Question 5: What does the term 'phase cancellation' describe in audio?
- A drop in high-frequency content
- Frequency buildup from reflection
- Reduction in amplitude when two out-of-phase signals combine (Correct answer)
- An increase in dynamic range
Correct answer: Reduction in amplitude when two out-of-phase signals combine
Phase cancellation occurs when two signals are out of phase (especially 180°), causing their amplitudes to subtract and reduce or eliminate the sound.
Question 6: Which phenomenon explains why you hear a lower pitch as an ambulance siren moves away from you?
- Reflection
- Diffraction
- Doppler effect (Correct answer)
- Refraction
Correct answer: Doppler effect
The Doppler effect causes the perceived frequency to decrease when a sound source moves away from the listener.
Question 7: In a transverse wave, the particles of the medium move in which direction relative to wave propagation?
- Parallel to wave travel
- Perpendicular to wave travel (Correct answer)
- In circular orbits
- Diagonally at 45 degrees
Correct answer: Perpendicular to wave travel
In transverse waves, particle displacement is perpendicular to the direction the wave travels — however, sound waves in air are longitudinal, not transverse.
Sound Design Waves And Sound 2
What happens to the wavelength of a sound wave when its frequency doubles while traveling through the same medium?