The main characteristics of electroacoustic system in modern stadiums can be summarized into three aspects:
★ Pay more attention to the sound effect of the auditorium and venue;
★ In order to meet the use needs of the opening and closing ceremonies of large-scale sports games or artistic performances, more attention should be paid to the corresponding "flow" sound amplification system;
★ Electroacoustic system pay more attention to the use of digital network transmission and control system.
The electroacoustic system of the gymnasium mainly includes
1. Meet the on-site sound amplification system for sports matches
2. Mobile sound amplification system for the opening and closing ceremonies and large-scale theatrical performances
3. Automatic priority broadcast system for multi-stage broadcast (including emergency broadcast)
4. Digital networked signal transmission and control system
5. Power amplifier and signal transmission fault automatic detection system
Basic requirements of sound amplification system in gymnasium
1. Sports venues are often used for sports matches or mass gatherings, so the basic requirements for the sound amplification system are to ensure the intelligibility (or clarity) of language amplification first. This may seem simple but in practice it is not easy to actually satisfy stadium seating (or the majority of seating) with good hearing.
2. If there is a large-scale opening and closing ceremony of the sports meeting or a large-scale high-level artistic performance, then the sound amplification system combined with the high-quality "mobile system" and the original "fixed" installation system will be used in combination, which will have a better effect and a more economic way.
3. The audience in modern stadiums is different from the traditional "spectators", but more of them are "fans" who support the participating teams. The atmosphere of the sports matches is warm. However, as for sound amplification, the level of "background noise" increases and is random, so it should be paid more attention in the design of sound amplification system.
Specification for acoustic characteristics of stadiums
1. Specification for acoustic characteristics of gymnasiums
"Code for Acoustical Design and Measurement of Gymnasiums" is a national industry standard edited by China Academy of Building Sciences and approved by the Ministry of Construction. It has been implemented since March 1, 2001. Its main contents include: General provisions; Architectural acoustics design; Noise control; 5 parts of sound reinforcement design and acoustic measurement (see JGJ/T131-2000,J42-2000 for details).
The competition hall is basically divided into the competition hall of the comprehensive gymnasium; Natatorium, competition hall, skating hall, etc.
2. Acoustic characteristics of stadiums
At present, there is no written standard for acoustic characteristics of stadiums in China. According to recent data from FIFA and DFB, the requirement of sound amplification steady state pressure level for stadium seats is about 105dB.
The requirements of the acoustic characteristics of the main sound amplification system of the newly-built or reconstructed stadiums for the 2008 Beijing Olympic Games;
Sound pressure level: 95dB in normal use; Maximum loudest pressure level (emergency broadcast)106dB.
Transmission frequency characteristics: language use 100Hz ~ 5KHz±5dB;
Music use 100Hz ~ 15KHz±5dB.
Language Clarity: Fast language transfer index Rasti ≥0.5.
It is important to point out that although the stadium is not an enclosed space, it cannot be treated simply as a free sound field in acoustic amplification design. Most stadiums have "canopies" above the audience seats for sound reflection. A typical stadium with a seating capacity of tens of thousands of people will have an empty reverberation time of about 5 seconds, and the reverberation time will also be about 3 seconds when the stadium is full with the audience. Therefore, sufficient attention should be paid to the design of sound amplification system.
The sound field control is the fundamental of sound amplification system design
Sound amplification belongs to the category of applied acoustics. No matter indoor or outdoor sound amplification can be separated from the acoustic environment (or sound field) where the sound amplification is used. The final effect of sound amplification is the embodiment of the comprehensive effect of construction sound and electroacoustic, so the basic problem of sound amplification system design is acoustics, which is to complete the analysis and design calculation of sound field of sound amplification based on construction sound.
If a sound amplification field is evaluated from the acoustic characteristic index of the sound amplification system, it mainly includes the maximum pressure level, transmission frequency characteristic, inhomogeneity of sound field and transmission gain, etc. If an amplified sound field is evaluated from the perspective of sound sensation, it mainly includes the clarity of language and music, as well as the sound quality effect of "many attributes" of replay, etc.
Whether it is indoor or outdoor sound amplification, there is more or less sound interference in the sound amplification field, perhaps this is inevitable. The presence of interference in the amplified sound field will affect the language clarity and music clarity of the amplified sound, and will damage the sound quality of the amplified sound replay. Modern sound reinforcement design is no longer "satisfied" with the sound pressure level and the ununiformity of sound field in the general sense, but pays much attention to the problem of sound interference in the sound field, and tries to reduce the sound interference to the minimum in the design, which is the focus of modern sound reinforcement design.