Sound Reflection: Why a Barrier Must Be 10m+

In summary, a barrier needs to be at least 10m tall for sound reflection because sound waves need a physical obstacle to bounce off of. A shorter barrier can still provide some sound reflection, but it may not completely block the sound. The distance between the sound source and the barrier also affects sound reflection, with a closer distance decreasing the effectiveness of the barrier. Materials that are dense and have a smooth surface, such as concrete and metal, are best for sound reflection barriers. Other factors that can affect sound reflection include the angle of the sound waves, wind direction, and nearby structures or objects.
  • #1
denian
641
0
i read in the book. it stated that sound can be reflected by a barrier and the barrier must be large ( 10metre or more ).

why?
 
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  • #2
In general, waves don't interact much with barriers that have a width that is smaller than the wavelength of the wave.

The "why" for this is a longer explanation.

a wavelength of 10 meters is a low frequency sound; you could hear a hand-clap echoing off a wall smaller than that. FOr any echo of voice, you would want at least a 5 m wall, but the larger the better.
 
  • #3


The reason a barrier must be at least 10 meters in order to effectively reflect sound is because of the wavelength of sound. Sound waves have a specific wavelength, which is the distance between two consecutive peaks or troughs in the wave. The longer the wavelength, the lower the frequency of the sound.

When sound waves hit a barrier, they will either be absorbed, transmitted, or reflected. If the barrier is too small, the sound waves will simply diffract around it, which means they will bend and continue on their path. This is why we can still hear sounds from behind a small barrier, such as a fence or a wall.

However, if the barrier is large enough, it will cause the sound waves to reflect off of it. This is because the barrier is now bigger than the wavelength of the sound waves, and the waves cannot diffract around it. Instead, they will bounce off the barrier and travel in a new direction.

A barrier that is at least 10 meters in size will effectively reflect sound waves with a longer wavelength, such as those produced by low frequency sounds like thunder or a large engine. This is why we often see large barriers, such as noise barriers on highways, which help to reduce the amount of sound that reaches nearby neighborhoods.

In conclusion, the size of a barrier plays a crucial role in sound reflection. A barrier must be 10 meters or more in order to properly reflect sound waves with longer wavelengths, providing effective noise reduction.
 

1. Why does a barrier need to be at least 10m tall for sound reflection?

Sound waves travel in a straight line until they encounter an obstacle, at which point they reflect off of it. To completely block the sound from reaching the other side, the barrier must be tall enough to act as a physical obstacle for the sound waves to bounce off of. A 10m barrier is typically enough to completely reflect the sound waves and prevent them from passing over the top.

2. Can a shorter barrier still provide sound reflection?

Yes, a shorter barrier can still provide some sound reflection, but it may not be enough to completely block the sound. Sound waves can diffract and bend around obstacles, so a shorter barrier may still allow some sound to pass through or over it.

3. How does the distance between the sound source and the barrier affect sound reflection?

The closer the sound source is to the barrier, the more the sound waves will spread out and diffract around the barrier. This can decrease the effectiveness of the barrier for sound reflection. Therefore, it is important to have a sufficient distance between the barrier and the sound source for optimal sound reflection.

4. What materials are best for sound reflection barriers?

Materials that are dense and have a smooth surface are best for sound reflection. This is because sound waves are more likely to bounce off of a solid, smooth surface rather than being absorbed or scattered by a rough or porous material. Concrete and metal are commonly used for sound barriers due to their density and smoothness.

5. Are there other factors that can affect sound reflection besides height and material of the barrier?

Yes, other factors such as the angle of the sound waves hitting the barrier, the direction of the wind, and the presence of nearby structures or objects can also impact sound reflection. These factors can cause sound waves to diffract or scatter, reducing the effectiveness of the barrier for sound reflection.

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