Before the advent of modern audio systems, a large number of large cinemas used to resemble the Opera Orchestra to create a similar "player" in front of the screen, which was later replaced by a horn mounted behind the screen. The opera house uses reverb to increase the volume to the audience. Many composers, including Mozart's large concert halls that don't like excessive reverberation, limit the expressiveness of their musical details. Mozart often prefers to perform outdoors so that the music outside the details can be heard.
Longer reverberations reduce the sharpness as the volume increases. The correct reverberation to evolve into an imaginary ideal is to reflect the short distance (short path length) of the surrounding area and the stage, and open a large area for a long distance (long path length).
It can be said that the specific classical music is suitable for reverberation of different characteristics. But no type of reverb is suitable for all classical music and all acoustic instruments. When the sound system developed, the cinema was plagued by the problem that the auditorium was too large to produce excessive reverberation.
This architectural acoustic problem is always plagued by the combination of hearing and visual effects, and often has little or no solution because it can't see anything (this is architectural acoustics). At that time, many architects believed that the urban environment, including our homes, especially in auditoriums and cinemas, should have better reverberation, and the absorption of sound was negated as “room lossâ€. Insufficient and erroneous understanding of acoustics directly contributes to excessive noise pollution to the city.
Many of the early large cinemas had little or no acoustic absorption, and the decorative ceilings provided good diffusion, but rarely absorbed sound, and no cinema audience intended to watch movies in a gorgeous lobby or movie theater. Money is wasted a lot, but it is not better used to improve the proper hearing of the film.
Modern and diverse theaters often have red pleated soft cloth materials hanging on the walls as the main decoration and high-frequency absorption, but may not contribute to the absorption of low frequencies. Ceilings that are often not acoustically absorbed, except for standard soundproof bricks, are sometimes used in office buildings. Welcome to China Home Theater Network
Echo and reverb
When the surround sound began to develop, some research institutes pointed out that this goal cannot rely on increasing the sound track. The audience only needs to listen to the mono cinema to understand the plot of the story, and the clarity and stereo imaging are destroyed by excessive echo and reverberation. The technical possibilities, coupled with good tracking, were limited. At the time, the dialogue of many movies was only produced in the middle channel speakers, left and right and their surround channels, providing only a minimum percentage of volume as a simple match for the picture. , as shown below:
A simple clapping applause will spur the echo in front of the cinema to the entire wall, floor and ceiling and evolve into reverberation, which will be clearly heard. As a general rule, the first 30 milliseconds of early reflections will be masked by some direct sounds and less audible. The echo and reverberation after 30 milliseconds will be heard in the room.
But the most common sounds from the speakers will continue and produce echoes and reverberations throughout the movie room, becoming the speaker's decreasing tail and continuing to cycle.
No matter who argues that these reverbs provide a pleasant aesthetic experience, it does cover and pollute new sounds to varying degrees and directly interfere with speech intelligibility, destructively changing what we hear, This made a story that undermined the movie.
Most modern cinemas are built to limit the sound from the cinema, often using curtain wall materials to absorb high frequencies, but have little effect on low frequency absorption (as shown below). If the folded soft cloth material absorbs 50% (-3 dB) of 500 Hz energy, the sound will have to collide with the soft cloth 20 times to reduce it to 0.0001% (-60 dB), so the -3 dB only hears a slight decrease. .
Comparing a small and large cinema made of the same building materials, the sound travels at a speed of about 344 meters per second. Each time the sound hits the wall, assuming that a% is absorbed and reflected, the average distance between the wall, floor and ceiling is described as 'mean free path' or 'average free time'. Welcome to China Home Theater Network
The average distance between walls in a small cinema is closer to that of a large theater, and the sound is more absorbed and reflected from the wall (in the same amount of time). In a large old movie theater with no soft cloth on the wall, in addition to a small amount of air attenuation, the high frequency reverberation energy will be less absorbed and louder. However, in a smaller one
The bass frequency has long been due to the wavelength and the directionality of the propagation, and the inverse square law does not apply to a small cinema. This is also similar to the spread of subwoofers.
The bass energy in a large theater will reduce the collision with the wall, and the inverse square ratio method will be applied to a certain extent. In other words, a large theater will have less bass energy in two-thirds of the position. Overall, the low frequency absorption is still insufficient, which will cause the low frequency sound spectrum to be blurred, and the action film depends on the effect of the bass energy, which is the latest design trend of cinemas in the history of cinema.
Sound absorption
Furniture, soft cloth and walls absorb acoustics, especially high frequencies, but the absorption of low frequencies is very limited. Further, the gap between the soft pack and the wall can be better absorbed including lower frequencies. The degree of absorption of sound energy depends on the type, weight and surface area of ​​the material. Mineral fiber cotton (glass fiber cotton) has the highest absorption capacity, which can convert air molecules into heat and consume them. It should be noted that the glass fiber material is irritating and prone to skin irritation, so it needs to be included in the fabric for use.
1/4 wavelength rule
The sound absorbing material must be placed at a distance from the wall and ceiling, preferably at the lowest frequency of 1/4 wavelength, which will include all higher frequency absorption, such as soft or fiberglass. Please note that the ceiling should also be included.
It is conceivable that it may be considered impractical to mount the acoustically absorbing material at a distance of 2 meters from all walls, but this is indeed closer to achieving a better sound absorption. In fact, this will only be turned on when the light is turned on. It is visually felt that the cinema is slightly reduced, but the cinema will have a greater sense of sound. And when the absorption environment is good, people feel relaxed and calm down, which can greatly enhance the enjoyment of enjoying the movie.
Before you rush out to buy a new solar powered dusk to dawn lighting, there are a few factors that you should consider. Here are the top features you will want to look out for in solar dusk to dawn lighting, and why they are important.
Weatherproofing and Durability
Dusk to dawn lights are meant to be used for outdoor spaces, so it is important that they can withstand the elements. All outdoor lights are waterproof to some degree. For the best waterproofing, you should look for a dusk to dawn light that has a high IP rating.
IP, or Ingress Protection, ratings are the measure of how well-sealed an encasing is. An IP over 65 will not just keep out moisture, but dust too, and will stay dry even if submerged in deep water. If you live in an area that sees a lot of storms and wet weather, a high IP rating is a good indication that you will be able to use your dusk to dawn outdoor lights for a long time without needing to replace or repair them.
Energy Efficiency
Solar powered lights get their charge from the sun, so they are generally very cost effective in your home. Leaving your solar powered floodlights on all night will not run up your energy bill. That said, the best dusk to dawn lights will still use energy efficiently so that they can hold their charge to stay up all night.
Brightness
Dusk til dawn lights, in general, are not as bright as other floodlights, because they are designed to stay up all night without losing their charge. The average dusk to dawn light will have around 1,000 lumens – that is bright enough to illuminate a larger outdoor space like a driveway or garden, but not so bright that it will disturb the neighbors or keep you up all night.
Like with all flood lighting, the brightness of dusk to dawn floodlights is measured in lumen. The higher the number of lumen, the brighter the light it will be. For reference, an average kitchen or bathroom bulb will have around 800 lumen or less – and some solar floodlights can go all the way up to 3,000 lumen.
Dusk To Dawn Solar Light, Solar Dusk To Dawn Security Light, Solar powered Flood Light Dusk To Dawn, Solar Powered LED Dusk To Down Floodlight, Dusk To Dawn Yard Light
Jiangmen Biaosheng Solar Energy Technology Co., Ltd. , https://www.bsprosolar.com