Does Sound Travel Up or Down? Here’s the Answer

Apartment living can introduce you to a cacophony of noises from many sources in all directions. If you’ve ever felt a neighbor’s bass booming through your living space in time to their awful music, then you know the problems this can present all too well. In such a situation, you may be looking to find the culprit and wondering where they live. Are they above or below? Well, does sound travel up or down?

So, which way does sound travel, up or down? Actually, neither. Sound will spread out in all directions unless something blocks or redirects it. It may travel at different speeds through different mediums such as air or solids, but it will continue to expand in all directions equally unless something acts upon those sound waves.

Interestingly, not all types of sounds will travel the same distance. Certain types of sound have much greater reach than others. Moreover, how the sound is traveling will also affect how far it can reach. Is the sound being transferred through solid surfaces such as walls and floors, or is it just projecting through the air? Let’s dig a little deeper into each of these and see how they affect the direction and distance which sound travels.

How Does Sound Travel?

Once a sound is created, it continues to project out in the form of sound waves that spread in all directions. The sound travels until it is redirected by coming into contact with another surface, such as a wall. Once it contacts a hard surface, many of the sound waves will be reflected and the wave will continue moving in a new direction with less energy. 

Sound can also be transferred through contact. Sound travels along hard surfaces by way of vibration, which can continue to travel through any surfaces that are in contact with the surface where the sound originated. 

Low-frequency sounds tend to travel more through contact as they have more energy and create more vibration. Higher-frequency sound travels through the air and is more easily absorbed and reflected than the lower-frequency noise.

Do All Sounds Travel the Same Distance?

So, how far can sound travel? As we mentioned, low-frequency sounds contain more energy, which means they also travel farther. On the other hand, high-frequency sound travels less distance overall since the sound waves contain less energy. This is the reason that they are reflected and absorbed more easily.

In an apartment, it’s much more difficult to tell where low-frequency sounds are coming from. The sound travel can be so great with low-frequency sounds that it could be coming from anywhere in your building. Alternatively, higher-pitched noises don’t travel as far. Thus they must be originating closer to your living space. This makes them easier to find and identify.

Do All Sounds Travel the Same Speed?

Since lower-frequency sounds contain more energy, you may expect the speed that sound travels at to be accelerated. However, all frequencies of sound move at the same speed. What affects differences in sound travel speed is the medium through which the noise travels. 

Compared to air, sound travels 15X faster through steel. This means that the pumping bass from a stereo anywhere in your building can easily travel through the structural steel beams that hold your apartment together and travel quickly from one end to the other. This can make it quite challenging to determine where an offending noise is even coming from. 

Water transmits sound four times faster than air, though nowhere near as fast as steel. Interestingly, sound waves even move faster in warm air when compared to cold air. 

In an apartment, this can mean that sound will find certain mediums through which it can travel fastest and allow it to be spread the farthest. For instance, noise may transfer through the concrete floor very quickly and spread across an entire level of the building. However, it may reach the wood used to construct the walls and no longer move as quickly. This may stop the sound travel much quicker, which prevents it from spreading to other floors.

Does Sound Travel Up or Down in an Apartment?

If you live in an apartment, you’re probably subject to a lot of extraneous noise. Footsteps are easy to hear above your head. But, how about that booming bass from a neighbor’s stereo? When you hear that, you’re wondering does sound travel up or down so you can find which neighbor is making all the ruckus. 

Sound will travel both directions evenly through the apartment building. However, the lower floors will tend to have more noise than the higher floors. This is because most of the noise is generated on the floors of the apartments above. 

Once a sound is generated on the floor, it will travel from the floor into the walls that connect. From there, it will spread out in every direction via vibration. That said, often the floor and walls are made from different materials that will transmit the sound at different speeds. 

As you get higher in an apartment building, there are fewer floors above your head where noise can be generated. On the bottom floor, there could be many rooms directly above you that are all starting points for noise generation. On the top floor, there’s nothing above your head to create noise, so you’ll only deal with noise coming up from below you.

Can upstairs neighbors hear downstairs neighbors? Not normal sounds like walking and talking. Generally, a thick concrete floor will separate you from the people below you. This floor transmits sound from contact very well, but that noise won’t travel as well up the walls since they’re constructed from wood. This is the reason you hear the footsteps above your head, but your upstairs neighbors don’t hear you walking around. 

Can you Direct Sound?

Sound can be directed, deflected, and absorbed. Sound waves carry energy which can be dissipated, reflected, and nullified. Once you kill the energy, the sound wave dies and the noise stops traveling. Of course, different frequencies respond differently to each of these methods of redirection.

High-frequency sounds can be reflected quite easily. All it takes is a hard surface. Since high-frequency sound waves don’t contain much energy, they don’t have enough power to cause vibration, which will transfer sound. 

When a high-frequency sound wave hits a hard surface, it’s reflected off the surface and moves away in a new direction. This deflection does absorb some of the sound wave’s energy, though, which means the reflected sound is quieter and has even less energy.

Sounds in the higher frequencies can also be absorbed fairly easily since they don’t contain very much energy. Instead of a hard surface, for absorption, you’re looking for something soft such as studio foam, blankets, even furniture can help absorb high-frequency sounds. 

Low-frequency sounds have different characteristics because they contain so much more energy and can create vibration. This means they can’t be deflected very well. The wave won’t bounce off a hard surface instead of being absorbed into the surface as vibration, which will transfer the noise.

Although they can’t be reflected very well, low-frequency sounds can still be absorbed. However, nullifying these high-energy sound waves will take a lot more than with the high-frequency noises. Lower sounds will require a lot of dampening material to absorb. 

Products designed to absorb higher-frequency sound waves tend to be 1” thick to about 3” thick. This is plenty for absorbing the energy of the higher sounds and nullifying them. The high-energy low-frequency sounds will require more in the line of 6”-12” thick sound-absorbing material to cancel that much energy.

For more information on controlling low frequency noise please see our articles How to Keep Bass From Going Through Walls, How to Block Out Low Frequency Noise.

 

How to Direct and Control the Noise

Many products exist to help absorb, deflect and redirect sound. Sound control panels come in many sizes, shapes, and colors. They can match your decor and will do a great job of containing the higher frequency sounds. Noise-control curtains can also prevent noises from coming in or out through windows, doors, and other weak points where sound often escapes.

Low-frequency sounds are much harder to get rid of. Since these high-energy sound waves are transferred most through contact, it’s best to decouple any low-frequency noise generators from any hard surfaces. For instance, subwoofers and large speakers should be placed on rubber risers or mats. This will help stop the transfer of sound through the floor and will reduce the amount of noise spreading to your downstairs neighbors. 

Conclusion

Apartment living can be a noisy situation that’s hard to control. If you’re like me, you’ve probably been wondering if sound travels up or down, trying to determine where the worst noise is coming from. Hopefully, now you understand how sound travels in all directions but moves at different speeds through different mediums. You’ve also got a few ideas for how to mitigate the issue, which I hope will help you find some peace in your home.

If you found this information useful, please share it with others who may also have too much excess noise in their lives. I will respond to any questions or comments left in the comments box below, so feel free to ask me anything.