CMP Acoustics and Recording Techniques 3 — Questions and Answers
Question 1: Which recording technique uses two microphones placed at 90° to each other with their capsules coincident, producing a stereo image with good mono compatibility?
- ORTF
- X/Y (coincident pair) (Correct answer)
- Mid-Side (M/S)
- Decca Tree
Correct answer: X/Y (coincident pair)
X/Y coincident stereo uses two cardioid mics with capsules overlapping at 90°, delivering a stable stereo image that collapses to mono without phase issues.
Question 2: What is 'room mode' in the context of studio acoustics?
- The setting on an outboard reverb unit
- A resonant frequency determined by the room's dimensions (Correct answer)
- The average SPL level maintained during tracking
- The EQ curve applied to compensate for monitor response
Correct answer: A resonant frequency determined by the room's dimensions
Room modes are standing waves at frequencies whose half-wavelengths fit between parallel surfaces, causing uneven bass response at different positions.
Question 3: A producer wants to record a drum kit with the most accurate stereo representation of the kit as heard by the drummer. Which overhead technique is most appropriate?
- Single mono overhead
- X/Y pair directly above the snare
- Recorderman technique (spaced pair from snare perspective) (Correct answer)
- Two mics pointing at the kick drum
Correct answer: Recorderman technique (spaced pair from snare perspective)
The Recorderman technique places two mics equidistant from the snare — one overhead and one over the shoulder — replicating the drummer's listening perspective.
Question 4: What is the purpose of using a high-pass filter (HPF) when recording a trumpet?
- Enhance the harmonic overtones
- Remove unwanted low-frequency rumble and stand vibration (Correct answer)
- Add warmth to the thin sound
- Increase the perceived loudness
Correct answer: Remove unwanted low-frequency rumble and stand vibration
A HPF below the trumpet's fundamental range eliminates mechanical rumble, HVAC noise, and stand vibrations that muddy the recording.
Question 5: In acoustic treatment, what type of material is most effective at absorbing low-frequency (bass) energy?
- Thin foam panels
- Fiberglass or rockwool bass traps in corners (Correct answer)
- Carpet on the floor
- Fabric-covered reflective panels
Correct answer: Fiberglass or rockwool bass traps in corners
Thick, dense mineral wool or fiberglass bass traps placed in room corners (where bass modes concentrate) are the most effective low-frequency absorbers.
Question 6: What is 'bleed' in the context of multi-microphone recording sessions?
- Analog tape saturation caused by high recording levels
- Unwanted sound from nearby instruments captured by a microphone (Correct answer)
- The spillover of audio between stereo channels
- DC offset in a microphone's output signal
Correct answer: Unwanted sound from nearby instruments captured by a microphone
Bleed (or spill) occurs when a microphone picks up sound from instruments other than its intended source, complicating mixing and editing.
Question 7: Which polar pattern allows a microphone to capture sound equally from all directions?
- Cardioid
- Figure-8
- Supercardioid
- Omnidirectional (Correct answer)
Correct answer: Omnidirectional
An omnidirectional microphone has a spherical pickup pattern with equal sensitivity at all angles, capturing the full acoustic environment.
CMP Acoustics and Recording Techniques 3
Which recording technique uses two microphones placed at 90° to each other with their capsules coincident, producing a stereo image with good mono compatibility?