Sound insulation performance
How to represent sound insulation performance
The sound insulation performance can be represented by the transmission loss. The transmission loss (TL: dB) is the decrease in power that occurs during transmission from a sound source room to a sound receiving room. In other words, the transmission loss can be determined by the difference between the incident sound and the transmitted sound.
[Example]In case of Fire Resistant Sound Insulation Wall“A-2000・WI”,
TL = Incident Sound - Transmitted Sound = 56dB
Sound insulation grading (D value): Sound insulation performance of a room
"Sound insulation grade" is set as a measure for evaluating the sound insulation performance between two rooms of an actual building. Requirements for sound insulation performance in orders for building condominiums and hotels are usually using this sound insulation grade "D value" (right figure) as its scale. That is, the numerical value of sound pressure level difference indicated by each reference curve at 500 Hz is called "D value".
D value is different even depending on the design specification of the room because "sound rerouting" is included even when the wall of two walls is constructed with the same sound insulating wall.
- D value represents the sound insulation performance (airborne sound insulation performance) between two rooms of an actual building.
- D value is measured in six bands at center frequencies 125, 250, 500, 1000, 2000, 4000 Hz and applied to the sound insulation reference curve of the Architectural Institute of Japan, and when all the measured values of the six bands exceed a certain standard, the numerical value of the largest reference curve out of the reference curves exceeding it is called "D value".
Sound Insulation Performance (TLD : Transmission Loss Difference): Sound Insulation of Walls
The value of TLD is used for rating the sound insulation performance (transmission loss difference) of wall itself when tested in acoustic laboratories.
TLD value is calculated by applying the above sound insulation performance to the reference curve of the Architectural Institute of Japan, similar to "D value".
However, unlike “D value”, which is represented in increments of 5 such as 40, 45 or 50, “TLD value” is valued in increments of 1, such as 41, 42, 43 and so on.
Since the acoustic characteristics of "TLD value" differs depending on the acoustic test room, even if the same wall is measured in different acoustic test rooms, it may be different from each other.
Effects of sound insulating wall (The relationship between D and TLD values)
The sound insulation performance (D value) between the two rooms at the actual construction site is obtained from the construction condition of the site from the sound insulation performance (TLD value) in the test room of the sound insulation wall, as well as by subtracting "total sound reduction and other reduction values" in accordance with actual room design specifications.
"D value" = "TLD value" - "Total of reduction values of rerouted sound and other sounds"
Total of reduction values of rerouted sound and other sounds
(the following illustration is in the case of a condominium)
Reduction values of rerouted sound and other sounds
- Sounds propagated through piping of bath unit-1dB
- Sounds propagated through ALC outer wall-2dB
- Absorption sound power is small in Western-style room-3dB
- Sounds routed through floor slab-4dB
Sum of reduction values-10dB
Therefore, the room-to-room sound insulation performance (D value) when using wall equivalent to TLD-55 is 55 - 10 = 45 dB. In addition to the above example, when windows and doors are adjacent (within 1.5 m), rerouting of sound occurs from the window / door portion, and the inter-room sound insulation performance (D value) further decreases.
Places where sound insulation is necessary
Sound insulation performance is necessary for partition walls, corridors of common areas and dwelling units of apartment houses. Besides this, high sound insulation performance is also necessary for walls of music studios, movie theaters (especially multiple-screen movie theaters such as cinema complexes), machine rooms and the like.
Sound insulation performance depending on construction methods
To improve the sound insulation of a wall between two rooms, it is necessary to improve both airborne sound and structure-borne sound. In general, walls incorporating gypsum boards consist of a layer of gypsum board applied to both sides of studs, so the walls have a cavity between gypsum boards. Although airborne sound can be isolated easily, structure-borne sound, however, is difficult to isolate because it can be easily transmitted through frame components (studs). Yoshino has been developing various walls to reduce structure-borne sound.
Both board layers on the wall have may contact point with underlying studs
(Common stud structure)
Both board layers on the wall have less contact point with underlying studs
(Staggered stud structure)
By combining construction methods and our variety of gypsum board products, we offer varied levels of sound insulation for our wall systems.
Renovation for improving the sound environment
In recent housing, although the housing using the walls with good sound insulation performance has become more important and emphasizing the sound environment, buildings that have been built for decades are using walls with low sound insulation performance and are far from comfortable living spaces. Therefore, Yoshino Gypsum proposes a reasonable renovation that improves the sound insulation performance of the wall by making use of existing walls.
Implementation of Housing Quality Assurance Act (Quality Assurance Law) promulgated in April 2000
Under this law, the government started to enforce performance labeling, enabling publicly designated institutions to evaluate the performance of houses, such as the structural strength of houses, safety in case of fire, consideration for elderly people, and actually inform potential buyers of such performance. Among them, there is a criteria for "sound environment".
【Performance Criteria in the Quality Assurance Law】
- Structure stability: Strength against earthquakes and typhoons
- Safety in case of fire: Detection of fire and noncombustibility
- Reduction of deterioration: Measures against deterioration of buildings such as moisture proofing, rust prevention, anti-termite treatment
- Consideration for maintenance: Ease of maintenance such as cleaning, inspection, as well as repair of water supply, drainage and gas pipes
- Thermal environment: Energy saving effect of houses
- Air environment: Consideration against chemical substances, ventilation measures etc.
- Lighting / visual environment: Percentage of open parts affecting the brightness of the room
- Sound environment: Reduction of noise
- Consideration for elderly citizens: Degree of accessibility such as steps and handrails
Grading of sound insulation performance of the partition wall stipulated in the Quality Assurance Law has grade 4 as the highest rank and descending in order of 3, 2, and 1.