Get Started

Ultrasonic Beacon: Silent Privacy Threat


Grayson Rodriguez

Jul 12, 2023 | 8 min read
  • Online threats




Ultrasonic Beacons . You may have never heard of this term, but they may have quietly influenced your life. Ultrasonic beacons are high-frequency sounds that are inaudible to humans but can be captured by the microphones of mobile devices , allowing marketers to track your behavior and preferences.




What are Ultrasonic Beacons?

How do Ultrasonic Beacons compromise your privacy? What risks do they pose?

What privacy data can be leaked through ultrasonic beacons?

How can you block Ultrasonic Beacons? What measures can you take to protect yourself?

Using MetroVPN to prevent intrusion by Ultrasonic Beacons


What are Ultrasonic Beacons?


Ultrasonic beacons are high-frequency sounds that are inaudible to humans. They can be emitted by media such as TVs, billboards, and websites to send information to mobile devices . This information can include product recommendations, coupons, surveys, and more, with the aim of attracting user attention, increasing engagement, and fostering loyalty.


When your mobile device, such as a smartphone, tablet, or laptop, receives an ultrasonic beacon, it captures the sounds through the microphone and converts them into digital signals . These signals can be recognized and decoded by applications installed on your device, enabling interaction with the ultrasonic beacons. For example, when you see an advertisement on TV, your phone may receive an ultrasonic beacon that prompts you to open a related app or website, or sends you a discount code or a chance to win a prize.


The working principle of ultrasonic beacons is clever. They enable wireless communication between different devices without the need for technologies like Wi-Fi, Bluetooth, or NFC. As a result, ultrasonic beacons can span across different platforms and channels, achieving wider and more precise marketing effects.


How do Ultrasonic Beacons compromise your privacy? What risks do they pose?


Ultrasonic beacons can be embedded in any type of speaker, such as TVs, computers, radios, or store audio systems. They can also be hidden in web pages, advertisements, or even websites. Whenever you open a web page or view an advertisement containing an ultrasonic beacon, your phone receives the signal. However, this requires prior authorization for certain apps to access your microphone. But often, users are unaware that they have granted such permissions to apps, or are unaware of how these apps will utilize these permissions.


What privacy data can be leaked through ultrasonic beacons?


① Websites you have visited.
② Advertisements you have seen.
③ Stores you have visited.
④ Products you are interested in.
⑤ Devices you use.
⑥ Individuals you are in contact with.

Individually, these pieces of information may not seem sensitive. However, when aggregated, they can create a very detailed user profile reflecting your interests, habits, preferences, social relationships, and more. Such user profiles can be used to deliver more accurate advertisements to you, sold to third-party organizations, or even exploited for scams or extortion.


In addition to privacy breaches, ultrasonic beacons pose other risks. Due to the need for rapid transmission and reception, ultrasonic beacons are difficult to authenticate and encrypt. This means they are susceptible to hacking or forgery. For example, hackers can use ultrasonic beacons to send malicious code to your phone or deceive your phone with a fake ultrasonic beacon.


How can you block Ultrasonic Beacons? What measures can you take to protect yourself?


Although ultrasonic beacons are inaudible, they may collect your privacy data without your knowledge. So, what can you do to prevent them? Here are some simple yet effective methods to help reduce the impact of ultrasonic beacons:

① Review installed applications

Do you really need all of the apps? Delete those you rarely use or have forgotten about. Some apps may use ultrasonic beacon technology without explicitly informing you, such as certain games, social media, or shopping apps.

② Check app permissions

For the apps you keep, carefully review the microphone permissions you have granted them. Disable microphone access for apps that do not require it.

③ Use firewalls or interceptors

There are browser extensions or mobile apps that can help intercept or block ultrasonic beacons. For example, SilverDog is a Chrome extension that acts as an audio firewall to block ultrasonic beacons. PilferShush is an Android app that listens for ultrasonic sounds and alerts you to which apps might be using them.

④ Use headphones or mute your device

When you do not need to use the microphone, plug in headphones or switch your device to silent mode. This prevents the microphone from capturing ultrasonic beacons and also avoids disturbing others.


Using MetroVPN to prevent intrusion by Ultrasonic Beacons


If you want to protect yourself from the intrusion of ultrasonic beacons, you need a reliable VPN service to encrypt your network traffic, hide your real IP address, and prevent any third-party surveillance or data theft. MetroVPN is an excellent VPN application that provides such services.

MetroVPN is a secure, anonymous, and fast VPN service that allows you to freely stream, game, and work online. It offers the following advantages and features:

① Multi-device

One account can protect up to 5 devices, not just your Windows device.

② Strict no-logs policy

It guarantees no recording or storage of users' browsing data and activities.

③ Easy to use

No complex processes, just open the app and connect with a single click to enjoy protection.

④ Ultra-fast speed

You can experience high-speed uploads and downloads with no delays or buffering, enabling seamless streaming anytime, anywhere.

⑤ Global servers

You can enjoy more online freedom as MetroVPN has 6500+ servers in multiple countries and regions.


  • Unblock
  • Netflix
  • Movie

จนกว่าจะได้รักกัน(Love at First Night): The New Wave of Thai TV Dramas

Apr 12, 2024 | 6 min read
  • Netflix

Unlock Netflix restrictions and watch the สาธุ now

Apr 11, 2024 | 7 min read
  • Movie

เทพยุทธ์สะบั้นฟ้าท้าสวรรค์(Burning Flames): Journey Through Adversity to Illuminate the Path of Freedom

Apr 9, 2024 | 6 min read

Best deal for MetroVPN 12 months plan

30-day money-back guarantee