Drones are becoming increasingly popular, but there are still some people who are unsure about them. One of the main concerns is how loud they are.
Characteristics: how loud are drones
Drones are aircraft without a human pilot on board. They can be of various sizes and shapes and may or may not have wings. A drone can be remotely controlled by someone on the ground, fly autonomously following a pre-programmed flight path, or both. They are also known as unmanned aerial vehicles (UAVs). The furthest range for drones is about 200 kilometers from their remote control station.
Some drones resemble regular planes while others look like helicopters with propellers. Some others still look like large model airplanes while remaining undetectable to radar detection systems, while some other very small ones even look like insects!
Different drones with various types of propellers make different types of sounds. The larger the drone, the louder the noise it makes. For example, a large military drone like the MQ-9 Reaper has a cruise speed of about 400 knots and produces a constant low droning sound similar to that of a small airplane. In contrast, smaller consumer drones like the DJI Phantom make a high-pitched humming noise.
There are three types of drones: the smallest one is widely used for spying and surveillance too. Some have a very specific task such as providing support with firefighting or delivering packages to people's homes, while others can even be used as weapons! Also, each type of drone lasts differently, cause it all depends on the brand, size, and specification.
Why does it happen?
Drones' propellers produce a very loud noise. The more powerful the drone, the loud level would be higher.
Noise generation is due to the high speed of air going through each propeller's ring. The pitch and number of blades also affect loud levels. Also, aerodynamic efficiency has an impact on how many sound drones make. It was proved that bigger drones are noisier than smaller ones due to amplifier effects, which means that they amplify the noise produced by their own propulsors because of increased power levels.
Loud levels of drones produce depend on their size, shape, and propulsion power (American Insitute of Aeronautics and Astronautics n.d.). Other factors that could affect the sound drones make are weather conditions (humidity, air pressure) or their speed. According to the American Institute of Aeronautics and Astronautics (AIAA) "sound from a small UAS(unmanned aircraft system) may seem quieter than a large jet at the same distance because the smaller UAS emits a lower sound level in all directions."
The loud level drones produce varies depending on the model. This makes them not appropriate for urban/residential areas where people are trying to have a peaceful life, unlike in rural areas where drones' noise is usually not heard because there aren't many people around. Some models are even quieter than others so they could be more appropriate for urban areas provided that their other characteristics (size, shape) are also adapted to city use.
Noise pollution and drones
To measure how loud a sound is, we use a unit called the decibel (dB). A normal conversation between two people is about 60 dB. When you shout, it measures about 80-90 dB and if you use a chainsaw, it measures around 100 dB.
A drone produces loud levels from 30 to 90 dB. That's as loud as heavy city traffic or a dishwasher! Noise from drones can be annoying especially when they fly near residential areas. In some cases, drones can also produce dangerous noise levels of more than 120 dB at close range and can cause hearing loss! That means that if someone was standing just 5 meters away from the source of that level of noise for one hour, their hearing would be damaged.
For instance, drones with propellers that are not well balanced make a high-pitched whining noise that can be heard from far away and can be really annoying. In addition, when drones are flown at night, the bright light they emit can also disturb people's sleep. Besides, if the propellers are made of metal, they can also reflect light and create a blinding effect.
How to reduce noise pollution from drones? There are a few things that can be done in order to reduce the noise levels produced by drones:
- Use quieter propellers: Some companies have developed special "silent" propellers for drones that make less noise.
- Use a sound deflector: A sound deflector is a device that is placed around the propellers and helps to redirect the noise downwards and away from people.
- Fly the drone further away: The further away the drone is, the less noise it will make.
- Keep the drone in good condition: A well-maintained drone will produce less noise than one that is not.
How loud is 41db?
If you want to know how loud is 41dB, it means that the noise produced by the drone is relatively quiet. In other words, this noise level is not harmful and won`t disturb your peace. You can use such drones near your house without worrying about the noise they make. If you compare something with 41dB noise, it would be like the sound of a refrigerator working in the next room or leaves rustling in the wind. In general, 41dB is not a loud noise and you can use such drones without any problems.
Drones and hearing loss
Even though noise from a drone is not that loud but it can still cause permanent hearing damage to your ears if you are exposed to it for too long at close range. In fact, many countries have laws regarding how loud drones should be when they fly over city centers because the main concern regarding drones isn't noise pollution, but rather their potential danger to public health by causing people ear problems such as tinnitus or hyperacusis.
What does this mean for us?
Don't forget that this kind of aircraft was designed with a goal in mind which is usually surveillance and spying! So while we love them for all the fun things we can do with them such as flying high in the sky and taking unexpected and epic selfies with them, we also need to be careful and considerate in order for us and our dear ones not to experience any kind of damage when these kinds of aircraft start flying over city centers.
What model is the loudest?
The most powerful drone among those being sold today is the DJI Inspire 1, which costs more than $3000. According to AIAA, it has a noise level of 75db at 100 feet, 85 dB at 300 feet, and 90db at 500 feet. It was tested by Doc Searls, who also mentioned that "most are too loud" for residential use (Doc Searls 2015).
This means that drones are not appropriate for urban areas or near houses. Their loud level is way too high for this kind of area, where most people are trying to have a peaceful life. So, such loud drones like the DJI Inspire 1 should be banned from flying near houses or in urban areas.
Now we know that there are different types of drones, some of them are really loud, and some are not. So, it depends on the model which you choose. If you want to buy a drone for your child, better take the quietest one. But remember that all drones are banned from flying near houses or in urban areas because of their noise levels.
But what about the smaller and less powerful drones?
What models are quieter?
According to AIAA the aircraft with "the lowest SPL is the Nano Hummingbird which emits less than 40db at 100 feet, 50 dB at 300 feet, and 55 dB at 500 feet". The disadvantage it has is that it only weighs 2 grams and can't carry a camera.
Another drone that emits not as much noise as other drones is the AeroScope One, which only produces 57 dB of sound at 100 feet. It costs around $100 and can be bought online, but you need an amateur radio license to use it because it uses frequencies reserved for amateur radio operations: 36-50 MHz and 72-76 MHz (American Reserve of Aeronautics & Astronautics n.d.).
The loud level is less in such modern drone models as they have been designed to emit low noise. That's why we can see them more and more often in city parks and other public places where people are trying to relax. You can buy your child a drone of the brand "Blade" which is really quiet (its noise level is 45-50 dB).
So, it all depends on the drone model. The smaller and less powerful drones are becoming more popular because of their low noise level. But if you want to buy a drone, make sure to check its noise level before using it near houses or in urban areas.
What drone can I buy for my child?
In order to help buyers choose the right drone for their children, AIAA published a list of the 10 quietest drones currently available as well as their respective noise levels at 100 feet distance:
Drone Noise level at 100 feet:
- AeroScope One 57 dB
- Nano Hummingbird 41 dB
- MJX X101 40 dB
- Yuneec Breeze 39 dB
- Blade Chroma 38 dB
- Disney Wings Mini 37 dB
- EACHINE E010 36 dB
- Dji Mavic Pro 35 dB
- Dji Phantom 3 Standard 34 dB
- HS170 Predator 33 dB
So, the loud level of all these drones doesn`t exceed 60 DB which makes them good for children to use. Choose the one that is more suitable for your child according to the noise level and other parameters. Still, many users may think that it is too loud for a city if a drone is used there.
However, if you consider buying HS170 Predator or Dji Phantom 3 Standard which has a loud level of 33 dB and 34 dB respectively, you may be sure that their use won`t make much noise. Propellers that are specifically designed to minimize noise will also help to keep the drone's noise level down.
Will drones be a good idea for urban life?
The loud level drones produce is not appropriate for urban areas, where people are trying to have a peaceful life. There's also the privacy issue, which is even more important in an urban environment. Because of this, there could be regulations issued by local authorities making it illegal to use noisy drones near houses or banning them from city limits altogether.
Another thing about using drones in cities is that they're smaller and lighter than other models so they could threaten public safety more. They can crash onto people if their propulsion fails and aren't as stable as bigger drones with four propellers. Drones with propellers that are big enough to be heard from the ground can be annoying and disruptive, so it's important to consider the noise they make before using them in an urban area.
The loud level is also a disadvantage of drones in an urban environment. Besides, urban life and loud noises don't go together. So, if you live in the city, it's better to buy a drone that is specifically designed for silent operation. At the same time, city life and drones could be a good idea if we see more and more regulations being put in place to make sure that these devices are used safely and don't disturb the peace.
Finally, loud drones are not appropriate for use near houses or in urban areas because of the noise they produce. If you want to buy a drone, make sure to check its noise level before using it near houses or in an urban environment.
Bottom line
Drones in urban areas could be a good idea but only if their loud level and size are adapted to city life. For example, we could see smaller and lighter drones flying around people's heads, which would probably cause more accidents than when used somewhere else because of their small size and lower weight.
On the other hand, noise levels produced by drones at 100 feet distance vary from 40 dB (AeroScope One) to 90 dB (Dji Inspire 1). Dji Phantom 3 Standard produces 34 dB of sound at this distance so it can be used near houses even in the rural area where most people try to have a peaceful life because their sound won't annoy them that much.