【 Weak current College 】 cabaret audio noise propagation characteristics and control-Power By 【 China power house network 】

1 Introduction

Cabaret audio equipment noise (Karaoke) harassment complaints, in recent years there has been an upward trend, especially in the residential area of singing rooms, hotels, etc. use Karaoke sound equipment, issued a strong noise, since this type of noise frequency bandwidth, high strength, noise penetrating ability is strong, and solid sound serious interference building living and rest. Because decorated staff lack the knowledge and experience, decoration structure, decorated out noise disturbance persists, give further control certain difficulties. 

This article on audio equipment noise propagation characteristics do research, and raised on the control of the structure from the decoration of the measures, noise for reference.

2 audio equipment noise propagation characteristics

Audio equipment noise generally 90 ~ 108db, and a wide frequency band, but to most low-frequency acoustic signal, often heard in the distance, low frequency sounds, such as percussion instruments sound, the kind of low-frequency ' Boom-Boom-"" sounds very tired brain. When the sound source on the first floor, noise can penetrate the building structure, the second floor noise reaching 40 ~ 50db or higher. 

We are a result of the arrival of the measured noise, as shown in table 1. The data from table 1 shows audio equipment noise attenuation characteristics of the noise attenuation is slow, each level noise attenuation 1db. 

Table 1 audio equipment noise propagation measurement

Measuring point location of sound source on the first floor, second floor, Room 3, room 4th floor room

Noise level db (a) 90 ~ 106424140

Field observations showed that the audio equipment noise at 35db following, it is hard to hear voices. Therefore, it can be used as a noise reduction 35db quantity pursuant to sound source noise level 100db, buildings in need of acoustics and noise attenuation should be about general design 65db noise volume should be considered by 70db. 

Audio equipment noise transmission has two: one is the air of the sound and solid sound. Through air media transmission, in accordance with the material for sound transmission loss calculation:

tl=20log(ωm/ρc)（1）

Type: ω = 2 π f, vibration round frequency: m-building component surface density kg/m 2; ρ c — air characteristic impedance. 

By the formula (1), under the same conditions (building elements surface density m, air-resistance ρ is the same as c), if the low-frequency signals, both circular frequency ω hours, materials for sound transmission loss is small, this is the audio device noise "penetrating" strong reasons. 

Some renovation roof surface density is small, contrary to the principle of "quality law", so that the sound transmission loss of building elements, such as a lower roof structure is the stars: 200mm glass wool + 0.8mm iron + 5-in-Board + 400mm air layer + 5-in-Board + 300mm glass wool + 5-in-boards. Although the sound layer, air layer is large, but the overall roof surface density (not building floor)-2 m, 22kg/increase of acoustics, noise-44db, second floor, is still available. 

Audio equipment noise propagation in another way it is a solid sound. Sonic or sound sources can stimulate the vibration caused by building elements to vibration forms that pollute the environment; or by building elements have a "second acoustic" so-called solid sound to noise pollution of the environment in the form. 

Solid borne sound without a fixed calculation methods, materials, general building elements of solid acoustic attenuation, 0.02 ~ 0.2db/m. Iron and steel and other metal components of attenuation smaller, can spread further. Table 2 is a commonly used materials of solid-borne sound attenuation. 

Table 2 General material solid acoustic attenuation

Materials iron brick concrete wood

Attenuation 0.01 ~ 0.03 0.02 ~ 0.13 0.03 ~ 0.02 0.05 ~ 0.33

The data from table 2 shows that noise through 5m distance of concrete wall, maximum attenuation before 1db. 

Audio equipment and renovation structure of vibration and vibration isolation on solid borne vibration and solid sound also has effects, such as audio equipment of speaker, due to improper placement method, and the building structure has a rigid connection, you will have a solid borne vibration and sound transmission. Observed that there is a rigid connection can increase 3 ~ 5db noise level of the sound effects or add 4 ~ 7db vibration transmitted vibration effects of. 

As a lightweight structure be established between the wall and the wall, by calculating its natural frequency for 122hz, and sound sources of noise in the main producing resonance frequencies that are similar to those that, since the room wall walls and building structures without isolation measures, wall of vibration directly to upstairs, measured vibration level for the same conditions 71db room 120 brick wall, vibration sense between significantly lower vibration level measured as the difference between 67db, 4db.

3 audio equipment noise control

Audio equipment noise prevention should take comprehensive measures of governance. Such as strengthening management, strict approval; strengthening of supervision, the promotion of governance; lessons learned, the promotion of advanced control technology, and so on. Due to the particularities of the noise of audio equipment, this article is primarily on audio equipment noise control technology. 

Audio equipment noise control technology, and general mechanical and electrical equipment. Audio equipment noise from the sound source on governance, General acoustics technology such as acoustic, noise, etc. are difficult to use. In addition, it is necessary to take into account the transmission of vibration and noise, and consider the acoustics in the sound field. 

Audio equipment noise control fromup to consider architectural structure to minimize the transmission of vibration and noise. To do this, we combine on-site decoration, for audio equipment noise study. There are three room decoration is as follows:

1 # the room walls are brick structure, walls without additional processing. Roof frame with rubber vibration isolation pads, roof structure for: 50mm polystyrene Board + 650mm air layer + 50mm glass wool + 100mm rock wool + 20 mm plaster. 

2 # room walls are light steel structure, roof structure: 200mm glass wool + 0 8mm iron + 5-in-Board + 400mm air layer + 5-in-Board + 300mm glass wool + 5-in-boards. 

3 # room ceiling structure and 2 # rooms are the same, but the walls and roof are filling with 150mm perlite. The volume of the room is approximately equivalent to 45m×6m×45m. 

Table 3-comparison of room decoration

Room number 1 # 2 # 3 #

Ceiling surface density 25 43 22.5

Wall and treatment of brick, unprocessed light steel, untreated brickwork, filling and handling

Test two ss-100, frequency 40 ~ 16khz speaker as a sound source, on three room, speaker vibration isolating rubber pad. Test points in the three corresponding upstairs room noise level measuring point in the middle of the room, the vibration level measuring point in the room on the ground. Test instrument-he5931 vibration and noise pollution, the sound source noise jidiao to 96 ~ 100db (average 98db), background noise values do, vibration level is vertical value vlz. Test results are shown in table 4. 

Table 4 sound transmission loss measurement results db (a)

Decoration room 1 # 2 # 3 #

Upstairs noise level 39 37 43

Atrial Septal volume 65 60 67

Ground vibration level 61,267,860 following, no vibration sensing

From table 3 can be seen in table 4, room decoration structures on audio equipment noise audio and vibration have great influence. 1 # room ceiling has taken a vibration isolation, surface density also large, improving the acoustics of a room, a room than 2 #, vibration levels increased 4db also lower than 66db. 2 # room walls are light steel structure have resonance and vibration transmission, affected the sound and vibration isolation effect. 

3 # room decoration structures, ceiling and wall large fill the face of perlite, density increases, while the sound absorption, thus having a better effect, sound and vibration isolation effect. 

Because 1 # room walls does not do any additional processing, you will have a direct impact on acoustic, producing solid sound. 3 # room ceiling and no vibration measures, therefore, has not reached the upstairs noise (a) the following 35db. But the scene was 3 # hearing room has almost no singing sound, residents are satisfied with it. 

4 conclusions

(1) audio equipment noise low-frequency components, penetrating ability, stars, ballroom, hotel, etc. of karaoke sound equipment noise, serious pollution to the environment. 

(2) high strength, low frequency audio device of Sonic sound transmission through the air and the architectural structure of the solid of the sound and vibration pollution of the environment, is one of his character. Therefore, the decoration of the rooms is to solve the problem of noise reduction of structure. 

(3) reasonable repair structure can make noise and vibration reduction to environmental standards.