CEA Studio Acoustics and Room Treatment

Question 1

What is the primary purpose of bass traps in a recording studio?

Accepted Answer

To absorb low-frequency standing waves and reduce room resonances

Answer

Bass traps are thick, dense absorptive materials placed in room corners where low-frequency standing waves (modes) accumulate. They reduce excessive bass buildup that would otherwise cause uneven low-frequency response in the listening environment.

Question 2

What acoustic phenomenon occurs when sound waves of a specific frequency create stationary patterns of constructive and destructive interference between parallel walls?

Accepted Answer

Standing waves (room modes)

Answer

Standing waves (room modes) are resonances created when sound wavelengths align with room dimensions such that reflected waves reinforce or cancel the direct wave. They cause certain bass frequencies to be unnaturally loud or quiet at specific listening positions.

Question 3

Which type of acoustic panel is designed to scatter sound energy in multiple directions rather than absorbing it?

Accepted Answer

Diffuser (e.g., QRD diffuser)

Answer

Diffusers scatter incident sound energy in multiple directions using a mathematically patterned surface (such as a Quadratic Residue Diffuser), reducing flutter echo and late reflections without making the room overly dead or removing a sense of spaciousness.

Question 4

What does 'RT60' measure in a room's acoustic response?

Accepted Answer

The time it takes for sound to decay by 60 dB after the source stops

Answer

RT60 (Reverberation Time 60) is the time, in seconds, required for a steady-state sound to decay 60 dB after the source ceases. Recording studios typically target RT60 values between 0.2–0.4 s; large concert halls may have RT60 values of 1.5–2.5 s.

Question 5

What is 'flutter echo' in studio acoustics?

Accepted Answer

A rapid series of discrete echoes caused by reflections between two parallel, reflective surfaces

Answer

Flutter echo is a characteristic 'ping-pong' or metallic ringing sound created when sound reflects repeatedly between two parallel, hard, flat surfaces (such as bare studio walls) before decaying. It is treated by adding absorption or diffusion to at least one surface.

(CEA) Certified Audio Engineer Practice Test

(CEA) Certified Audio Engineer Practice Test

CEA Studio Acoustics and Room Treatment