With the continuous enrichment of cultural life, the renovation of the original auditorium and the construction of a new multi-purpose hall are also developing rapidly. Although many constructors have incorporated a lot of manpower and material resources into the renovation, due to the lack of understanding of the basic functional requirements of the auditorium, the use of new or modified sites has not been satisfactory. This raises the question of how to make structural and acoustical designs for the new (reconstructed) auditorium when it is planned, and to rationally allocate equipment according to demand, in order to achieve a good visual and audio effect of holding various events in the auditorium. The function of the auditorium is usually a large-scale assembly, taking into account both theatrical performances and film screenings. This is what people usually call a multipurpose auditorium.

In the national standard “Code for Design of Acoustics for Theatres, Cinemas and Multi-purpose Halls” (GB/T50356-2005), general requirements are put forward: the sound quality of the auditorium of a multi-purpose auditorium should be mainly clear, and it should also be available everywhere in the hall. Appropriate relative strength and uniformity. No defects, such as echoes, multiple echoes, trembling echoes, and sound-focusing resonances, can occur at any position in the auditorium and are not affected by equipment noise, noise in the projection room, and noise from the external environment. The primary purpose of the multipurpose auditorium is to meet and report, and to meet the linguistic intelligibility, taking into account other uses such as general performances and film screenings. Therefore, there is a high demand for verbal clarity and intelligibility. In order to ensure that the auditorium has good audiovisual conditions, it is necessary to understand the relevant building acoustics knowledge.

Project case

Addis Ababa Auditorium

Overview of Acoustic Engineering in Addis Ababa Auditorium:The Esse Auditorium is a multipurpose venue with a total length of 49 meters, a width of 45 meters and a height of 10.2 meters; an area of approximately 6480 square meters and an auditorium seating area of 2665. The auditorium acoustic design should meet the large-scale conference and various Requirements such as performance activities. Its main acoustic design is clear language, full music, no acoustic defects, meeting the requirements of the national acoustic standards. The acoustic characteristics of the auditorium:

The volume of the internal space is large, and the required sound absorption is large.

The interior is a place of public activity, which requires high requirements for environmental protection and firefighting. Therefore, the project is required to meet the relevant national regulations.

The museum is a public event venue and therefore has high requirements for the beauty of the decoration.

It is required that sound-building materials have good anti-impact and anti-wear capabilities.

Therefore, the design mainly uses wooden sound-absorbing structures, MLS diffusers, acoustic diffusers, and cloth acoustic panels to basically solve the influence of the parallel sides of the Esse Auditorium on the sound quality of the interior, so that Esse Auditorium meets the requirements of the national acoustic standards.

Addis Ababa Auditorium Acoustic Sound Design

Smallpox: Auditoriums and theatres cannot exceed 5.5 seats/m3 per seat, so the ceiling height above the stage is controlled between 6 and 7 meters. The ceiling of the audience hall ceiling cannot exceed 9.5 meters. According to the overall control principle of the reverberation of the auditorium, soft mattresses are installed on the ground and fibration carpets are laid on the walkways to reduce the strong reflection sound energy on the ground. Therefore, sound absorption processing may not be considered for ceilings.

Stage backdrop: According to the function of the auditorium, the main function is to hold reciprocal and academic reports and exchanges. In order to prevent the sound from being reflected from the background wall to the microphone during the meeting or communication, the whistle could be generated by the wheat whistles. Therefore, medium-high-frequency sound-absorbing materials should be used for the background wall. Recommended material 50mm thick cloth acoustic board. In order to avoid the monotonous visual effect of the background wall using the swimsuit material, mix and match 18 mm acoustic decorative panels.

Walls on both sides of the stage mouth: The walls on both sides of the stage mouth play an important role in enhancing the lateral energy factor of the front seats. Therefore, acoustic reflection plates (hanging plates) reflecting sound energy are recommended in this area. The reflector thickness cannot be less than 18mm and the amount is about 180 square meters.

Walls on both sides of the audience hall: 9m away from the stage mouth. Since the wall surface is closest to the sound level on both sides of the stage mouth, the acoustic energy decays slowly. The sound energy reflected from the wall surface into the audience seat This will create a longer reverberation time in the middle of the auditorium to make the audience feel cloudy. Therefore, diffusion material is suitable for this site. The sound reinforcement material is recommended to use an MLS diffuser with a wide diffusion frequency and mix acoustic diffusers with ideal low-frequency diffusion (this diffuser can be customized according to the project requirements). The thickness of the MLS diffuser is not less than 33mm, and the acoustic diffuser height is not less than 200mm.

The middle part of the first floor of the audience hall has a large area of doors and windows. It is recommended to use sound-absorbing curtains to handle the phenomenon, so as to reduce the rumbling sound caused by the strong reflection of the glass and confusion of the audience’s hearing. The back wall of the first floor of the audience hall, the back wall of the second floor, and the side wall of the second floor are far away from the sound source, and the attenuation of sound energy at mid-high frequencies is obvious. Therefore, it is recommended to use materials with sound absorption at low frequencies, such as wooden perforated sound-absorbing structures. The perforation rate of the wooden perforated sound-absorbing structure was 11%, and the sound-absorbing black felt was attached after filling the 50 mm sound-absorbing cotton.

Seat

In order to reduce the audience’s influence on the indoor sound quality, the sound absorption of the seat satisfies the following requirements: Seat sound absorption performance table

The surface layer of the seat is made of woven fabric and has good sound-transmitting performance. The upper and the back of the backrest are non-perforated reflective surface materials, and the lower surface of the seat is a perforated material.

Walkway

In order to reduce the reflection of acoustic energy from the walkway surface, it is recommended that the walkway be made of fibrillated carpets with a certain sound absorption function. The thickness of the carpet is not less than 10mm.

Sound insulation design

With reference to the provisions of GB/T50356-2005, the background noise limit in the museum is NR-35, so the sending and returning ducts leading to the halls, etc., should be equipped with noise elimination, noise reduction, and shock absorption measures. There is a barrier that causes regenerated noise. In order to control the noise value of the indoor background and reduce the interference of the indoor noise on the auditorium, it is recommended that all indoor walls be acoustically treated.

Air conditioning section

After air-conditioning system equipment vibration and noise are directly introduced into the hall, air-conditioning noise introduced via the air inlet and return air inlets is the main source of noise and must be given adequate attention.

Addis Ababa auditorium acoustic design effect

Beautiful and elegant decoration, good visual comfort.

The sound-absorbing material does not have the dust pollution of glass fibre particles, nor does it have formaldehyde pollution, and meets the air quality and environmental protection requirements of the site.

It has a good sound. That is, low, medium, and high tones are properly balanced.

Sound-absorbing material to meet the fire rating requirements.

The sound in the venue is relatively clear, and there are no sound defects such as silent dyeing.

After the project is implemented, the acoustic environment and the on-site environment are suitable.

Addis Ababa auditorium acoustic material performance requirements The material performance requirements used in this design plan are as follows:

1) Acoustic sound absorption performance meets acoustic design requirements;

2) No glass fibre dust pollution, to meet environmental protection requirements;

3) Formaldehyde emission reaches E1 level or above;

4) Fireproof performance of sound-absorbing material meets fire-fighting requirements.

5) Has mold and moisture resistance; With excellent durability, stability and resistance to mechanical damage.