Micro-Perforated Backing Layer for Low-Frequency Ceiling Acoustics

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Solution Overview

Problem

Existing suspended ceiling tiles exhibit low sound absorption at low frequencies and resonance phenomena in the plenum, which negatively impact sound insulation.

Innovation Solution

An acoustic insulation product with a micro-perforated back layer having specific airflow resistance and perforation characteristics, combined with a porous material panel, enhances sound absorption and insulation by dissipating acoustic waves through viscous friction and controlled airflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a traditional suspended ceiling tile with airtight rear veil is used, then sound insulation between rooms is maintained, but sound absorption at low frequencies deteriorates and resonance phenomena in the plenum occur

Engineering Contradiction:

Improvesound absorption at low frequenciesVSAvoidsound insulation between rooms

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies a micro-perforated back layer with controlled porosity (perforation rate between 0.1% and 10%) and specific airflow resistance (5-20 kPa.s/m). This porous structure allows low-frequency sound waves to penetrate and be absorbed by the acoustic panel while maintaining sufficient resistance to prevent excessive sound transmission through the plenum, thus resolving the contradiction between sound absorption and sound insulation.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent changes the airflow resistance parameter of the back layer from the traditional high resistance (airtight) to a controlled range (5-20 kPa.s/m). This parameter modification enables the back layer to function as an acoustic impedance matching layer, improving low-frequency sound absorption while maintaining adequate sound insulation performance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the back layer is made airtight to prevent sound transmission, then sound insulation is improved, but resonance phenomena in the plenum are exacerbated

Engineering Contradiction:

Improvesound insulationVSAvoidresonance phenomena in plenum

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The micro-perforated back layer acts as a porous material that allows controlled airflow through the plenum. This prevents the buildup of resonant pressure that occurs with airtight constructions, thereby reducing resonance phenomena while still providing effective sound insulation through the controlled impedance mismatch.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The micro-perforated back layer serves as an intermediary element between the room and the plenum. It mediates the acoustic energy transmission by allowing partial passage of sound waves, thereby damping resonance phenomena while maintaining the insulating function.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a thick back layer is used to improve sound absorption, then low frequency absorption improves, but the complexity and weight of the ceiling tile increase

Engineering Contradiction:

Improvesound absorption at low frequenciesVSAvoidstructure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The micro-perforated back layer provides efficient sound absorption at low frequencies through its porous structure and controlled airflow resistance, eliminating the need for thick conventional back layers. This achieves effective sound absorption with a thin, simple structure.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

By changing the airflow resistance parameter of the back layer to the optimal range (5-20 kPa.s/m), the patent achieves enhanced sound absorption performance with a thin layer (thickness less than or equal to 1 cm), avoiding the need for thick and complex structures.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves sound absorption, particularly at low frequencies, and reduces resonance-induced sound propagation, thereby enhancing overall acoustic insulation.

Implementation Method 1

dissipating acoustic waves through viscous friction

Methodology Applied

Scientific EffectViscous friction: Viscous Damping

Implementation Method 2

ensure good absorption of acoustic waves

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentEP3956528B1Acoustic insulation product comprising a rear layer

Publication Date: 2026.02.11 SAINT GOBAIN ISOVER

Figure 1~2

AI summary

The invention relates to an acoustic insulation product (5) comprising a panel (1) made of porous material, based on foam or fibres, comprising a first face, referred to as back face (20), intended to face towards a wall, and a second face, referred to as front face (30), situated on the opposite side to the back face (20), and a layer, referred to as backing layer (2), which adheres to or is linked or coupled at least in part to the back face (20) of the panel (1) made of porous material, the backing layer (2) having an airflow resistance of between 5 kPa.s/m and 20 kPa.s/m, preferably between 7 kPa.s/m and 15 kPa.s/m. The acoustic insulation product according to the invention is able to improve both acoustic insulation and noise absorption.