CMP Acoustics and Recording Techniques Questions and Answers 1 — Questions and Answers
Question 1: A producer is recording a podcast with two hosts sitting directly across from each other at a table, using a single microphone. To capture both voices clearly while rejecting sound from the sides, which microphone polar pattern is most suitable?
- Cardioid
- Omnidirectional
- Bidirectional (Figure-8) (Correct answer)
- Shotgun
Correct answer: Bidirectional (Figure-8)
A bidirectional, or figure-8, polar pattern is equally sensitive to sound from the front and the back of the microphone, while rejecting sound from the sides (90 degrees off-axis). This makes it ideal for capturing a conversation between two people facing each other with one microphone placed between them.
Question 2: When recording an electric bass guitar, a producer wants to capture both the sound of the amplifier and a clean, unaffected signal simultaneously for later processing (a technique known as re-amping). What single piece of equipment is essential for splitting the bass's high-impedance signal, sending one line to the amp and another balanced, low-impedance line to the mixing console?
- A compressor with a sidechain input
- A DI (Direct Input) Box (Correct answer)
- A high-pass filter
- A multi-pattern condenser microphone
Correct answer: A DI (Direct Input) Box
A DI (Direct Input) box is designed to convert an unbalanced, high-impedance instrument signal into a balanced, low-impedance microphone-level signal suitable for a mixing console. Most DI boxes feature a 'thru' or 'bypass' output that allows the original, unaffected signal to be sent to an amplifier on stage or in the studio, making it the perfect tool for this scenario.
Question 3: A vocalist is recording a track with a sensitive condenser microphone. During playback, the producer notices distracting, low-frequency 'pops' on words with hard consonants like 'p' and 'b'. What is the most common and effective tool used to prevent this issue during recording?
- A pop filter (Correct answer)
- A de-esser plugin
- A shock mount
- A dynamic microphone
Correct answer: A pop filter
A pop filter is a screen placed between the vocalist and the microphone designed to disperse the blasts of air (known as plosives) that occur when singing or speaking hard consonants like 'p' and 'b'. This prevents the sudden air pressure from overloading the microphone's diaphragm and causing the characteristic popping sound.
Question 4: A producer is setting up a home studio in a small, rectangular room. They notice that certain bass frequencies sound significantly louder or weaker depending on where they stand in the room. This phenomenon, caused by sound waves reflecting between parallel surfaces and combining, is known as:
- Phase cancellation
- The Doppler effect
- Reverberation time (RT60)
- Standing waves (or room modes) (Correct answer)
Correct answer: Standing waves (or room modes)
Standing waves, also called room modes, occur when the wavelength of a sound relates to the dimensions of a room, causing reflections between parallel surfaces (like walls) to reinforce or cancel out the original sound at specific frequencies. This creates an uneven low-frequency response with noticeable peaks and nulls at different locations within the room.
Question 5: To minimize phase cancellation and comb filtering when using two microphones on two different sound sources (e.g., two separate guitar amps), which common microphone placement guideline should a producer follow?
- The inverse square law
- The 3:1 rule (Correct answer)
- The X/Y coincident pair technique
- The 80 Hz roll-off rule
Correct answer: The 3:1 rule
The 3:1 rule is a guideline used to reduce phase issues when multiple microphones are picking up multiple sources. It states that the distance between two microphones should be at least three times the distance from each microphone to its intended sound source. This ensures that the bleed from one source into the other's mic is significantly lower in level, thus minimizing audible phase problems.
Question 6: A producer needs to record the powerful, high-SPL (Sound Pressure Level) sound of a snare drum and a loud guitar amplifier. Which type of microphone is generally best suited for these applications due to its durability and ability to handle high volumes without distortion?
- Ribbon microphone
- Small-diaphragm condenser microphone
- Dynamic microphone (Correct answer)
- Tube condenser microphone
Correct answer: Dynamic microphone
Dynamic microphones are known for their robust construction and ability to handle very high SPLs without distorting. This makes them the standard choice for close-miking loud sources like snare drums, tom-toms, and electric guitar cabinets.
CMP Acoustics and Recording Techniques Questions and Answers 1
A producer is recording a podcast with two hosts sitting directly across from each other at a table, using a single microphone.
To capture both voices clearly while rejecting sound from the sides, which microphone polar pattern is most suitable?