Acoustic design in halls and auditoriums focuses on controlling reverberation to ensure clarity and richness of sound.
1. What is Reverberation Time?
Reverberation time is the time taken for the sound intensity to drop by $60 \text{ dB}$ after the source has stopped.
2. Why extremes are bad:
• Too high (Maximum): Sound persists for too long, causing overlapping of syllables and making speech unintelligible (excessive echoes).
• Too low (Zero): The hall feels "dead." Sound lacks richness and fails to reach the back of the room effectively.
3. The "Optimum" Requirement:
A "good sound effect" requires a balance. Speech requires shorter reverberation times ($\approx 0.5 \text{--} 1.0 \text{ s}$) for clarity, while music requires slightly longer times ($\approx 1.5 \text{--} 2.0 \text{ s}$) for a full, resonant quality. Therefore, designers aim for an
optimum time based on the hall's purpose.