When it comes to acoustic solutions, two terms often come up: sound absorption and sound transmission. While they might seem similar, they serve different purposes in the realm of soundproofing and noise reduction. This article aims to clarify the differences between sound absorption and sound transmission, helping you make informed decisions for your acoustic needs.

What is Sound Absorption?

Sound absorption refers to the process where sound waves are absorbed by a material, reducing the echo and reverberation within a space. This is particularly useful in environments like recording studios, home theatres, or office spaces where clarity of sound is crucial.

Materials

Common materials used for sound absorption include acoustic foam panels, fabric-wrapped panels, and even acoustic ceiling tiles. These materials are designed to trap sound waves, enhancing the acoustic quality of a room.

The Science

Sound absorption works by converting the energy of sound waves into heat. This process is crucial for reducing noise levels and improving the overall acoustic environment. For a deeper understanding, you can refer to this scientific article on the principles of sound absorption.

Sound Absorption

What is Sound Transmission?

On the other hand, sound transmission deals with the passage of sound waves through a material or structure. The goal here is to prevent sound from traveling from one space to another, making it essential for residential buildings, hotels, and industrial settings.

Materials for Sound Transmission

Materials effective in mitigating sound transmission are generally denser and may include mass-loaded vinyl, soundproof drywall, or specialized acoustic wall panels. The National Research Council Canada has conducted extensive research on materials that are effective in reducing sound transmission.

Products and Approaches

Key Differences

  1. Purpose: Sound absorption improves the sound within a space, while sound transmission prevents sound from escaping or entering a space.
  2. Material: Absorptive materials are generally softer and lighter, whereas materials for sound transmission are denser.
  3. Application: Sound absorption is ideal for improving acoustics within a room, while sound transmission solutions are better for isolating rooms from external noise.

Two different products and approaches are required for the two different issues.

Sound absorption products are installed on hard surfaces such as walls and ceilings. The fact that they are installed on the exposed areas of existing surfaces makes them easier to install without requiring renovation.

Products that reduce sound transmission generally need to be installed behind the walls, floors or ceiling, and are not visible within a room. The general idea is to create a ‘room within a room’. This could include creating a substantial cavity (such as 15-20cm) between the two adjoining spaces and fill it with heavy insulation to prevent the sound penetrating. This is difficult and expensive to retrofit to an existing structure and requires significant renovation.

To put the difference into perspective, you can drop the noise level in a busy restaurant by 5db to 10db with a very good sound absorption treatment. This is a significant and noticeable reduction to those in the room (the decibel scale is logarithmic, so every 10db is twice as much sound). But when people talk about ‘soundproofing’— like you might see in a recording booth or home theatre — they are generally looking for a reduction of about 40db between rooms. You cannot achieve this kind of result with sound absorption alone — only take the edge off.

Real-world Applications

These concepts arenot just theoretical but have real-world applications. For instance, sound absorption is commonly used in educational institutions to improve focus and comprehension. On the other hand, sound transmission solutions are often employed in healthcare settings to ensure patient privacy.

Conclusion

Understnading the differences between sound absorption and sound transmission is crucial for selecting the right acoustic solutions for your specific needs. Whether you’re looking to improve the sound quality within a space or isolate a room from external noise, knowing these terms will guide you in making an informed decision.