DASM consults on soundproofing and acoustic treatment solutions for Sotetsu International Hotel Project in Ho Chi Minh City.
In early March 2022, The Institute for Development & Application of Sound Materials – DASM was invited to survey noise levels and provide soundproofing and acoustic solutions for several rooms at the Sotetsu Hotel Project in Ho Chi Minh City. The project covers a total area of nearly 800m², with 120 rooms, 19 floors, and 2 basement levels, designed to meet international quality standards.
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Sotetsu Hotel – International Standard for High-Quality Accommodation
To meet the international quality standards required for the 4-star hotel project, and as per the requirements of the Sotetsu Group, one of Japan’s major hotel investment and management corporations, the main contractor Vinata International entrusted DASM to directly conduct noise surveys and consult on soundproofing and acoustic solutions for this important project.
Although The Institute for Development & Application of Sound Materials was only established in 2021, it has quickly become the best choice for evaluating soundproofing and acoustic quality in buildings. With the most advanced measuring equipment in the world, along with a team of specialized experts trained in acoustics, we are confident in delivering professional solutions and services regarding soundproofing and acoustics. We also provide consulting and supply of soundproofing and acoustic materials that meet high standards for construction projects.
Soundproofing and Acoustic Solutions for the Sotetsu Hotel
To meet international quality standards, particularly for a 4-star hotel like Sotetsu, it is essential to assess and address noise in the rooms. The Institute for Development & Application of Sound Materials applied various measurement standards such as ISO 16283, ISO 140, ASTM E-336, ISO 354, and ISO 717 to survey the project and propose suitable soundproofing and acoustic solutions.
| Measurement Parameter | Standard |
|---|---|
| Airborne sound transmission between rooms | ISO 16283, ISO 140, ASTM E-336 |
| Sound Absorption | ISO 354, ISO 717 |
| Noise Criterion Calculation (NC) | ISO 3382 |
| Impact Sound Insulation | JIS A 1418 |
According to the ISO 16283, ISO 140 standards, the report includes the average sound levels L1 and L2 across frequency ranges for each measurement. Based on these parameters, we assess the soundproofing capacity of walls, partitions, and any structure. The NC (Noise Criterion) index is determined based on the background noise level in each surveyed location. The TL (Transmission Loss) index is based on the space’s absorption, which is enhanced by any interior furnishing.
Measured Rooms
For the Sotetsu Hotel, we measured the sound levels in P. 404, P. 406, and P. 407 on the 4th floor to evaluate the noise and soundproofing. These rooms were selected for detailed noise analysis, and the following dimensions were recorded:
| Room | Volume [m³] | Large Window Area [m²] | Gypsum Wall Area [m²] | Main Door Area [m²] | Large Window Dimensions [m²] | Bathroom Door Dimensions [m²] |
|---|---|---|---|---|---|---|
| P. 407 | 49.81 | 9.126 | 10.9 | 3.86 | 1.55 x 2.42 | 1.94 x 2.4 |
| P. 406 | 41.56 | 11.61 | N/A | 3.86 | 1.55 x 2.42 | 1.94 x 2.4 |
| P. 404 | 41.76 | 9.018 | 8.91 | 3.86 | 1.55 x 2.42 | 1.94 x 2.4 |
NC Index (Noise Criterion)
Noise arising from open spaces or around buildings, such as HVAC systems, traffic noise, etc., not only causes discomfort, stress, and fatigue for occupants but also reduces productivity and focus, thus affecting safety. In extreme cases, it can even interfere with communication abilities.
NC (Noise Criterion) or NC curve is a way to describe measured noise levels across a frequency spectrum, from 63.5Hz to 8kHz. It is useful in identifying noise levels from mechanical systems, such as engines, in noise-sensitive environments like hotels and hospitals.
The criterion sets the upper limits for each octave frequency band, which should not be exceeded.
| Classification | Application | Recommended NC Levels |
|---|---|---|
| Residential | Private homes or apartments | 25-35 |
| Suburban homes | 25-30 | |
| Bedrooms | 20-30 | |
| Living rooms | 25-35 | |
| Hotel | Individual room or suite | 25-35 |
| Meeting or banquet rooms | 25-35 | |
| Service and support areas | 45-50 | |
| Hallways, corridors | 40-45 | |
| Public Areas | Courtrooms | 30-40 |
| Libraries | 35-40 | |
| Churches, mosques, temples | 30-35 | |
| Factory | Production areas | 40-65 |
| Administrators / Accountants | 40-46 | |
| Office | Meeting / conference rooms | 25-35 |
| Private offices | 30-35 | |
| Open office areas | 40-45 | |
| Business machines/computers | 40-45 | |
| Rest areas / waiting rooms | 40-45 | |
| Hospital and Clinics | X-ray departments | 35-40 |
| Theaters | 25-30 | |
| Patient rooms | 35-40 | |
| Laboratories | 35-40 | |
| Consultation / Exam rooms | 35-40 | |
| Hallways / Public areas | 40-45 | |
| Commercial Areas | Theaters | 30-35 |
| Restaurants | 45-50 | |
| Sound recording / Broadcast / TV Studios | 15-20 | |
| Performance / Concert / Recital Halls | 15-20 | |
| Sports stadiums | 45-55 | |
| Spas / Facial treatments / Massage centers | 25-35 | |
| Retail stores | 40-45 | |
| Fitness / Exercise rooms | 40-45 | |
| Schools | Auditoriums | 35-40 |
| Classrooms | 35-40 |
TL Index (Transmission Loss)
TLD: Transmission Loss Difference: The difference in energy loss through soundproof walls.
Each soundproof wall, depending on its material and structure, will have a different energy loss level. Depending on the purpose, different partition wall designs can be created. Transmission loss tends to increase at higher frequencies, and at low frequencies, soundproofing performance can be improved with appropriate additional measures.
Once sound waves encounter a barrier (such as a wall or partition), three mechanisms occur simultaneously: Reflection, absorption, and transmission through the wall. A portion of the sound is reflected back to the source, some is absorbed by the barrier, and the remaining sound is transmitted to the space on the opposite side of the barrier. Transmission loss is the term used to describe the performance of the barrier as a soundproofing element between two spaces. Transmission loss increases as the soundproofing performance of the barrier increases. It is given by:
Transmission Loss=log(WIWT)\text{Transmission Loss} = \log \left( \frac{WI}{WT} \right)
Where:
- WI is the sound power (in watts) incident on the wall.
- WT is the sound power transmitted to the space on the opposite side of the barrier.
Measurement Methods and Process
To evaluate the soundproofing and acoustical treatment of a construction or space, the measurement process involves several key steps. The main methods for measuring soundproofing include using specific instruments and procedures to assess sound levels and transmission losses.
Typically, The Institute for Development & Application of Sound Materials uses advanced equipment for sound level measurements, ensuring high accuracy during surveys. Measurements are conducted in both controlled environments and under real operational conditions to ensure that the final results reflect actual performance.
The process includes:
- Initial survey: Identifying the areas of concern and establishing where the soundproofing treatments will be applied.
- Measurement of baseline sound levels: Measuring the ambient noise levels within the areas and spaces before any soundproofing treatments are applied.
- Application of soundproofing treatments: Implementing soundproofing solutions such as materials, structural modifications, or changes to the layout.
- Final measurement: After the treatments are applied, a final sound measurement is taken to ensure the effectiveness of the treatments, comparing them to industry standards.
The measurement results are analyzed using various indices and criteria, including NC, TL, and STC (Sound Transmission Class). These results determine the effectiveness of the soundproofing efforts and indicate any areas that may need further improvement.
Measurement Locations
Each room will have 6 measurement points identified at the most acoustically disadvantageous locations, where there are unstable fluctuations in sound intensity. An inconsistent environment will affect the determination of the average sound level in each room. This is the reason why sound measurements are taken at these specific points.
The measurement locations for each room are identified as follows:
Each measurement point must maintain a minimum distance of 1 meter from the wall and 1 meter from the floor to ensure the accuracy of the sound intensity measurement.
Location 1
This is the point closest to the window frame. Due to the structural design with only a single layer of glass, soundproofing capabilities can be unstable and may be weaker.
Location 2 & 3
These two positions are influenced by the internal structure of the room, particularly in areas with right-angle corners.
Location 4
This location is near the door, where several factors such as door gaps, joints with the wall, and door edges can negatively affect soundproofing. These are the positions most vulnerable to sound leakage.
Location 5
This is the area where two different shapes of the room intersect, resulting in a change in sound intensity levels.
Location 6
This is the central area of the hotel room where the sound intensity level remains the most stable.
Measurement Location Outside the Scaffold
This is a special location used to measure the soundproofing ability of the walls where the interior of the room meets the exterior. In this case, a sound source is placed on the scaffold, and a sufficiently large sound source is activated, much louder than the ambient noise. It is only when there is a significant difference in sound intensity that the soundproofing ability of the wall or partition can be determined.
Measuring Instruments
Two instruments are used to experimentally determine the NC and TL coefficients:
- Sound Level Meter Norsonic 140
2. Sound Source OMNI 4
While the Sound Source generates a sound source louder than the background noise for determining the TL coefficient, the Sound Level Meter allows for the measurement of sound intensity at each measurement point across the 1/1 octave or 1/3 octave frequency range.
Results
The results will be presented separately for NC and TL. Each result is accompanied by a verification sheet along with an explanatory report.
The results were analyzed after the on-site measurement. The NC value achieved was NC 24, which meets the required standards. For gypsum walls and glass doors, the required 50dB was achieved at high frequencies, but the performance at low frequencies did not meet expectations.
Especially at the main door, the results did not meet the requirements due to the construction and soundproofing methods not being up to standard.
Soundproofing and Acoustic Treatment Solutions from DASM
After collecting and analyzing the data from the noise surveys, DASM proposed soundproofing and acoustic treatment solutions that meet both the acoustic performance standards and the aesthetic and functional needs of the project. These solutions are tailored to improve the acoustic comfort for guests, ensuring a quiet and pleasant environment in the hotel rooms.
