Multi functional Hall Acoustic Design Scheme

1、 Project Overview

This plan takes the multifunctional hall with a building area of about 176.1 square meters, a height of about 3 meters, and an indoor volume of about 530m3 as an example to explain the architectural acoustic design scheme of the multifunctional hall.

The main acoustic requirement in a multifunctional hall is to ensure clear listening of language sounds. This requires strict control of the full frequency reverberation time (especially low-frequency reverberation time) in the multifunctional hall, and controlling low-frequency reverberation time is a difficult task in the acoustic field that cannot be solved by decorative professionals.

Design requirements: In accordance with the national standard "Code for acoustic design of theaters, cinemas, and conference halls" and the proposed acoustic indicators and measures, various parameters are controlled through design calculations, various defects are eliminated, and the internal acoustic environment quality of the space is improved to ensure the normal use of functional rooms. To achieve both aesthetic and practical effects in interior decoration design.

Design objective:

1) Obtain appropriate reverberation time and frequency characteristics for indoor space, and control the intermediate frequency reverberation time within the range of 1.0s under full field conditions to achieve a good sound quality environment and speech clarity.

2) Acoustic defects such as silent standing waves, trembling echoes, and multiple echoes.

2、 Basic parameters of acoustic design

2.1 Reverberation time

The reverberation time T60 refers to the time it takes for the sound source to stop producing sound after the indoor sound field reaches a steady state, and from this moment until the sound pressure level decays by 60dB. It is one of the most important objective indicators for evaluating the sound quality of a room.

The calculation formula for T60 is:

Among them, the average indoor sound absorption coefficient is:

V - Room volume, m3;

S - Total indoor surface area, m2;

α— Indoor average sound absorption coefficient;

M - Sound attenuation coefficient in the air (M-1);

Si - surface area of each indoor part, m2;

α I - the sound absorption coefficient corresponding to Si;

Nj - number of people or objects, m2;

α J - The sound absorption coefficient corresponding to Ni.

The length of reverberation time directly affects the listening effect. Excessive reverberation time can affect the clarity of listening and may cause whistling and hinder the transmission gain of the sound reinforcement system. Being too short can make the sound dry, weak, and unnatural, affecting people's normal ability to distinguish sound. Therefore, it is necessary to arrange sound-absorbing materials reasonably to make the frequency characteristic curve tend to be basically flat, in order to achieve an appropriate reverberation time.

2.2 Background noise (RN)

Environmental noise mainly includes external environmental noise of buildings and internal environmental noise of buildings.

The external environmental noise of buildings includes: transportation noise, factory noise, construction noise, commercial noise, social life noise, etc.

The environmental noise inside the building includes: pedestrian flow noise in equipment rooms such as pump rooms, air conditioning rooms, and elevator rooms, lobby and corridors, as well as floor impact noise generated by upper level personnel activities.

2.3 No sound quality defects such as low-frequency resonance and acoustic staining

Trembling echoes are a series of closely followed reflected pulse sounds caused by the same original pulse sound. It is very easy to produce vibration echo phenomenon between parallel surfaces.

Sound focusing refers to the reflection of sound through a concave surface and focusing it on one point, resulting in uneven distribution of the sound field. Concave curved walls are prone to sound focusing.

To improve the sound listening effect of the conference room, it is not only necessary to control the reverberation time inside the hall, but also to eliminate acoustic defects such as sound focusing and trembling echoes, so as to make the speech in the hall clear and the sound field uniform.

3、 Standard specifications and design basis

3.1 "Building Sound Insulation and Absorption Structures" (National Building Standard Design Atlas 08J931);

3.2 "Code for Fire Protection Design of Interior Decoration of Buildings" (GB50222-95);

3.3 "Code for Indoor Environmental Pollution Control of Civil Building Engineering" GB50325-2001;

3.4 "Quality Standards for Sound Environment" GB3096-2008;

3.5 "Measurement Specification for Hall Reverberation Time" GBJ76-84;

3.6 "Code for acoustic design of theaters, cinemas, and multi-purpose halls" GB/T50356-2005;

3.7 Requirements of Party A and related architectural and decorative drawings

4、 Acoustic Analysis of Places

1. The multifunctional hall has a volume of 528m3, which is prone to producing echoes and multiple echoes, making it difficult for people to hear.

2. 17.5m long, with a large free sound path, it is prone to echo generation.

3. The venue is rectangular and has parallel walls, which are prone to producing vibration echoes between them.

4. The ceiling of the venue is parallel to the roof, and parallel to the floor tiles can easily form multiple reflections. The above phenomena can cause sound defects in the venue, affecting the listening effect of the audience. It is necessary to install acoustic materials reasonably in order to improve and eliminate sound defects.

5、 Acoustic scheme suggestions

metope

The main functional requirements of the multifunctional hall are: primarily for meetings; In order to improve the uniformity of indoor sound field, ensure the clarity of indoor language, eliminate acoustic defects such as indoor echoes, multiple echoes, and trembling echoes, sound-absorbing materials with strong sound absorption will be selected to achieve the goal of controlling short reverberation time.

In order to reasonably control the reverberation time in the multifunctional hall, maintain the current decoration design effect, eliminate inherent sound defects in the building, and improve the uniformity of the conference sound field, various acoustic decoration materials should be comprehensively arranged in the multifunctional hall, and the shape, specifications, installation angle, and installation method of these materials should be strictly controlled.

It is recommended to install a 90mm E-grade sound-absorbing board on the wall, with a height of 3m. The vibration and multiple echoes of parallel walls are eliminated through the sound absorption of the wall.

6、 Design effect

6.1 The decoration is beautiful and generous, with a comfortable and good visual experience.

6.2 The sound-absorbing material is free from dust pollution caused by fiberglass particles and formaldehyde pollution, meeting the environmental requirements for air quality in the premises.

6.3 Have good timbre. Moderate balance of low, medium, and high tones.

6.4 Clear listening in the venue, silent staining and other sound quality defects.

After the implementation of the 6.5 project, the sound environment and on-site environment are suitable, meeting the full reverberation time index and meeting national standards.

7、 Material performance requirements

90mm thick E-grade sound-absorbing board

(1) Finished product - multifunctional hall use.

(2) Structure: Install sound-absorbing cotton embedded in the keel, with wood and stone groove hole board finish.

(3) The thickness of the wooden slot hole board is 15mm, the slot width is 3mm, the slot edge distance is 13mm, and the perforation rate is about 11%.

(4) The 24-hour release of glass fiber particles is 0.01mg/m3, which is better than the national standard limit of 0.15mg/m3.

(5) The requirements for product sound absorption coefficient are as follows:

Explanation: Both environmental performance and sound absorption coefficient require testing reports from national authoritative institutions.

8、 Characteristics of the plan

8.1 Acoustic calculations shall be conducted using years of mature experience and calculation software;

8.2 The noise in the venue has been improved to a certain extent;

8.3 Acoustic materials are aesthetically pleasing and have strong plasticity;

8.4 Free from fiberglass dust and formaldehyde pollution, meeting environmental protection requirements;

8.5 The wall sound-absorbing material has good impact resistance and anti fouling performance.

9、 Explanation

The measures to ensure that the designed sound absorption effect meets the design standards are:

1) This plan is based on specific acoustic materials for simulation, analysis, and calculation. It is necessary to strictly follow the acoustic parameters of the acoustic materials used in the design to achieve the design effect. If a new building acoustic material is replaced, it must be appraised by a building acoustic engineer before use;

2) The construction quality should be strict and accurate. During the construction process, construction must be carried out according to the acoustic material parameters confirmed in the design. If there are any changes, they should be notified to the acoustic engineer and calculated and confirmed before replacement.