Components of Acoustic Response in a Space:

• Direct Sound: Sound that travels directly from the source to the listener without reflections.
• Early Reflections: Initial reflections from nearby surfaces that impact sound clarity.
• Reverberant Field: The accumulation of late reflections that contribute to the sense of “ambience” in a space.

Reverberation Time (RT60): Definition and Calculation

RT60 is the standard measurement for quantifying reverberation. It is defined as the time it takes for the sound pressure level to decrease by 60 dB after the sound source stops.

Sabine Formula

For simple spaces, RT60 can be calculated using Sabine’s formula:

Where:

V = Volume of the space (in m³).
A = Total acoustic absorption area (in m² sabins).
The total acoustic absorption area is calculated by summing the product of absorption coefficients (α) and surface areas (S) for each material in the space:

Practical Example:

An auditorium with a volume of 1,000 m³, walls clad in wood (α=0.15), and a carpeted floor (α=0.45) will have a longer RT60 than one equipped with highly absorptive acoustic panels (α>0.8).

How Reverberation Affects Sound Quality

1.Intelligibility:

Excessive reverberation time reduces speech clarity, which can be problematic in settings like conferences or churches.

2.Timbre and Sonic Richness:

Controlled reverberation enhances sound perception in concert halls, adding “body” to the audio.

3.Frequency Control:

Reverberation impacts low frequencies the most, as they tend to accumulate in corners and walls, causing undesirable effects like booming.

Reverberation Control: Practical Strategies

1.Passive Treatment: Absorptive and Diffusive Materials

• Absorptive Panels: Reduce reverberation time by eliminating unwanted reflections.
• Diffusers: Redistribute reflections evenly to avoid sound energy concentrations

Application:

In a theater, installing ceiling-mounted absorptive panels and diffusers on rear walls can improve both clarity and sound uniformity.

2.Sound System Design

A well-designed speaker system can minimize interaction with reflective surfaces.

• Directional Speakers: The IBZA Series or Array Series line arrays can focus sound on the audience, reducing reflections from ceilings and walls.
• Low-Frequency Control: Cardioid subwoofers, can minimize bass buildup in reverberant spaces.

Example:

In a church with high ceilings and stone walls, combining an Array Series system with a  SW215 subwoofer in cardioid configuration would optimize intelligibility by reducing reflections.

3.Digital Signal Processing (DSP)

DSP tools are essential for adjusting acoustic response in real-time:

• Equalization: Attenuate problematic frequencies that prolong reverberation.
• Delays: Synchronize speakers to avoid echo effects.
• Filters: Use low-pass or high-pass filters on amplifiers like the T Series or TDAP Series to control spectral content.

Case Study: Acoustic Optimization of a Multipurpose Theater

Scenario:

An 800-seat theater used for both drama and concerts struggles with intelligibility and excessive reverberation time (RT60 = 2.5 s).

Solution:

Acoustic Treatment:

• Install absorptive panels on side walls.
• Add diffusers at the back of the venue to improve sound dispersion.

Sound System Design:

• Use Array Series line arrays for uniform, controlled coverage.
• Configure cardioid SW Series subwoofers to reduce unwanted low frequencies.

Digital Processing:

• Adjust EQ and delays using DSP-equipped amplifiers from the TDAP Series.

Simulation and Measurement:

• Use EASE Focus to simulate expected acoustic behavior after adjustments.
• Measure the new RT60 to ensure it falls between 1.2 and 1.6 seconds, ideal for a multipurpose theater.

Conclusion

Controlling reverberation and decay time is critical for ensuring optimal sound quality in any enclosed space. By combining passive acoustic treatment, sound system design, and digital processing tools, you can transform a problematic acoustic environment into a flawless one.

If you need advice or specific equipment for a project, contact us. Our team can help design custom systems, conduct acoustic simulations, and optimize any space using Tecnare technology.