Creating a sense of spaciousness is not a common acoustical design objective. It is more related to architectural design and visual aesthetics.

An acoustical absorber is designed to absorb sound waves, thereby reducing their energy and minimizing reverberation.

Concrete walls are not typically used as acoustical absorbers due to their high density and low sound absorption coefficients.

Reverberation time is the time it takes for sound to decay by 60 dB after the source has stopped.

Increasing the volume of the room does not directly affect reverberation time. It can, however, reduce the overall sound pressure level.

An acoustical diffuser is designed to diffract sound waves, thereby scattering them in different directions and reducing the impact of standing waves.

Flat panels are not typically used as acoustical diffusers as they do not provide effective scattering of sound waves.

Clarity index is a measure of the clarity of sound in a room, particularly the ability to distinguish between direct and reverberant sound.

Increasing the volume of the room does not directly improve speech intelligibility. It can, however, reduce the overall sound pressure level and make it easier to hear.

Reverberation is the unwanted buildup of sound energy in a room due to multiple reflections of sound waves from surfaces.

Increasing the volume of the room does not directly control noise. It can, however, reduce the overall sound pressure level.

Echo is the unwanted reflection of sound waves from a surface, resulting in a delayed and distinct repetition of the original sound.

Direct echo is not a type of echo. It refers to the initial sound that reaches the listener directly from the source without any reflections.

Standing waves are the phenomenon of sound waves bouncing back and forth between two parallel surfaces, resulting in a pattern of alternating areas of high and low sound pressure.

Increasing the volume of the room does not directly control standing waves. It can, however, reduce the overall sound pressure level and make them less noticeable.