What Do Drones Sound Like

What Do Drones Sound Like?

One of the surest ways to detect a drone flying above your house is by its sound. If you have never owned one, you may wonder, what do drones sound like?

Most people think drones sound like helicopters. Helicopters are heavier and use petrol engines; hence, they’re louder than drones. Drones are light but may be noisy or silent based on their type and model.

Drones with big propellers may be noisy. Their sound resembles that of a swarm of (angry) bees. The sound range could be between 35 to 90 DB based on their purposes and size.

Read on as I discuss the different drone sounds and how to identify them after flying different drones over the years.

What Do Drones Sound Like?

Drones may sound like a swarm of bees angrily buzzing above your head. However, this sound may be steadier, more sustained, and more consistent than a swarm of bees. Hence, it is less complex than the sound of bees.

Others sound like a lawnmower operating at a distance, a busy road, or a hummingbird.

Large drones flying close to you will emit about 70 to 80 Decibels (DB). However, when they fly higher to about 100 ft, the sound lowers to about 35 to 40 DB.

What Makes A Drone Noisy?

What Makes A Drone Noisy

Drone propellers, when rotating at a high speed, create vibrations. These vibrations generate audible sounds you can hear when a drone is flying near you.

The motor’s power and the propellers’ shape and number, aerodynamics, and drone material determine the volume and pitch of the drone sound.

Propellers

Propellers

When the propellers spin, they create a force to help the drone lift and move. Smaller drones with smaller propellers may have lower noise. In contrast, loud, deeper sounds come from drones featuring large propellers.

However, the material used on the propeller also determines how quiet or loud the drone is.

Even so, most modern drone propellers are made of carbon fiber. Though these propellers could hurt you if they come into contact with you, carbon fiber propellers are lightweight hence less noisy.

Notably, propellers with many blades are quieter than those with fewer blades. Also, the propeller’s curvature and angle may equally determine how loud your drone will be. 

Drone Motors

Drone Motors

Drones may feature brushed or brushless motors. High-end drones have brushless motors. Hence, they’re quieter.

On the contrary, drones with brushed motors are cheaper but louder. 

Aerodynamics

The drone’s body and frame highly affect its sound. Drones that feature less bulky aerodynamics experience higher air resistance.

Hence, they’re louder. On the other hand, drones featuring a smooth, streamlined design are quieter as they encounter minimal air resistance.

Material

Drones can be made of metal, plastic, or carbon fiber. Metal makes drones more noisy, while carbon fiber and plastic composites make them quieter.

How Can Drones Be Detected Through Sounds?

How Can Drones Be Detected Through Sounds

Detecting drones by their sounds is fun and makes you look like a professional pilot. Here’s how to detect a drone by its sounds.

Buzzing Sound: Most drones make a buzzing sound. It’s typically a high-pitched sound and is likened to a swarm of angry bees. It’s also a continuous and distinctive sound. 

Sound’s Pattern and Rhythm: The drone’s sound follows a particular pattern and rhythm, making it easy to know its usage. The pattern and rhythm of the sound may differ based on the use and type of drone.

Agricultural drones make a steady, consistent sound when spraying or monitoring farms. The high speed of racing drones gives them a rapid, rhythmic sound.

Flight speed and sound: How a drone takes off says a lot about its purpose. For instance, as racing drones maneuver speedily into the air, they produce a highly noticeable sound.

A drone for aerial cinematography may have a controlled, smooth sound when capturing cinematic footage.

Drone Sounds By Their Uses

The type and use of a drone determine how it’s made. Hence, different drones used in different fields have varying sounds. Let’s discuss them below.

Racing Drones

These are designed to fly fast and hence have fast-spinning propellers. They produce a unique buzzing, loud sound when taking off, about 80 DB. They have a smooth design and are made to be nimble.

Toy Drones

Due to their small size, toy drones make a soft, buzzing sound because of their small motors. Since they’re only used for fun, their noise level ranges between 40 to 50 DB.

Commercial Drones

Commercial drones spray crops, monitor their growth, shoot aerial videos, take photos, and deliver goods; hence, they have fast-spinning propellers.

These propellers make a steady, whirring, and soft hum sound. The range of their sound is 60 to 70 decibels (DB).

Military Drones

The role of military drones is to spy or fight. Hence, they have tough materials and sound engines and can fly for an extended time.

Their noise level, based on the type of military drone, can range from 50 to 90 DB. Drones used for missions that need stealth will be quieter than those used in active combat.

How Do I Reduce The Noise Of My Drone?

Imagine being hired to shoot videos at a relative’s wedding or church event. After replaying the video to check on the quality before delivery, you hear some buzzing noise in the background. It’s annoying and could mess up the overall quality of your videos.

Below are effective ways to reduce your drone’s sound.

  • Use nano-fiber material to make noise-reduction shrouds. These materials protect the blades and also capture the sound and direct it upwards, hence minimizing it.
  • Use raked wingtips; they’re more acoustic-friendly than propellers.
  • Replace fast-spinning propellers with large, slow-spinning ones to lower the sound of your drone.
  • Smooth propellers produce lesser noise, so install smooth ones. Alternatively, use sandpaper to make the current propeller surfaces smooth.

Noise from drones not only affects the footage you record, but it also has implications in our every day life.

According to this briefing by the Institute of Acoustics, drone noise can be more annoying than that of cars, affecting people and animals. The briefing also goes ahead to suggest ways of managing drone noise which include;

  • Researching further on the impact of noise from drones.
  • Minimizing the number of flight s needed.
  • Reducing the noise from the drones as much as possible by exporing different designs and technologies.
  • Creating designated flight paths.

Conclusion

Drone sounds differ based on the size and type of the drone. Bigger drones have bigger propellers, hence more louder.

Drones can sound like buzzing bees, busy roads, a hummingbird, or a lawn mower operating at a distance based on how they’re being flown and used. So, their sounds could range from 20 to 90 DB.

The higher the number of propellers, the lesser the noise, but the lower the number, the higher the noise. Fewer propellers have more work to do when the drone is flying, hence more noise.

You can reduce your drone’s noise by making the propellers smooth, using slow-spinning propellers or nano-fiber material to make noise-reduction shrouds.

Author
Peter Karanja

Peter is a licensed drone pilot and drone fanatic. He owns a DJI Air 2S that he uses to shoot videos for fun, enjoyment and for clients.

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