Why do hearing aid users experience connectivity problems?
In our last blog post, we reviewed what Bluetooth® wireless technology is, the two main different types of Bluetooth, and how Bluetooth hearing aids work. In this blog, we’ll look at some common reasons why users may experience connectivity problems with their hearing aids – and suggestions to minimise these issues.
There are many reasons for connectivity problems, but the most common are:
- Bluetooth technology uses the 2.4 GHz frequency band
- Bluetooth technology needs a clear line of sight for best transmission
- The hearing aid needs to be within range of the device
- Bluetooth technology hops between different frequencies
- The pairing process is complex
The 2.4 GHz frequency band
The 2.4 GHz frequency band is part of the Industrial, Scientific, and Medical (ISM) zone of the radio frequency (RF) spectrum. Bluetooth Low Energy divides the frequency range into 40 channels, each 2 mHz wide. FCC licensing is not required in this band, so it’s full of other devices including Wi-Fi, microwaves, security cameras, baby monitors, garage door openers, and much more! The signal can receive interference from any of these sources and can lead to a poor Bluetooth connection.
- What might help: Avoid other devices that operate on the same frequency band, such as those mentioned above. Keep some distance between these devices and hearing aids to minimise potential issues.
Bluetooth technology needs a clear line of sight
Bluetooth range is affected by obstacles including walls, floors, humidity, precipitation, people, and even a person’s own body. In fact, the human body is one of the most difficult obstacles as we are mostly water and water is a super absorber of Bluetooth.
The advertised maximum range of a Bluetooth device assumes no obstacles. The amount of signal loss varies by the type of obstacle and the material. Think about when you are trying to hear someone in the next room and the difference between the volume and clarity of what you can hear if the wall that separates you is made of wood compared to concrete. That signal loss is what is happening to the Bluetooth signal.
- What might help: To help improve signal strength, keep the hearing aid and the connected device in close proximity with a direct line of sight, and avoid obstacles, such as walls or large objects, between them. If possible, position the device on the same side of the body.
The hearing aid needs to be within range of the device
One of the most difficult scenarios for keeping a stable connection is if the user walks in and out of range of the connected device, causing reconnections. The reconnection process is complicated and can fail, which leads to disconnection. Hearing aid users are at a greater risk of walking away from their phone than a headphone user. Typically, when a headphone user walks away from their connected phone they take off the headphones and reconnect when they need to use them again. A hearing aid user is not going to take off their hearing aids when they are done streaming from their phone.
- What might help: Staying within the recommended Bluetooth range specified by the manufacturer, typically around 10 meters (30 feet). As mentioned earlier, keep in mind that obstacles and signal interference can reduce the effective range, so it’s important to try to maintain a direct line of sight between the hearing aid and the connected device.
Bluetooth technology “hops” between frequencies
Part of what makes Bluetooth technology robust can also interfere with the signal. Bluetooth technology uses adaptive frequency hopping to overcome interference. The primary device (in our case, a phone) will maintain a channel map that classifies how well each channel is functioning and shares that map with the secondary device (in our case, a hearing aid). The channel map is continuously updated. The Bluetooth signal will change frequencies if it encounters interference in a particular channel, maybe from a Wi-Fi signal or other device. However, when the signal hops, it may make the audio choppy or even interrupt the signal completely.
- What might help: If users experience frequent signal drops or interruptions, they can try turning off other nearby Bluetooth devices or moving away from crowded areas with multiple Bluetooth signals.
The Bluetooth pairing process is complex!
Pairing devices can be very complex and can be disrupted if there is corruption of any data packet exchanged during the process. If this happens, the pairing process (or “handshake”) has to start over and it slows down the pairing process. Devices that are already paired may also interfere with the pairing process of a new device. For example, it is possible that a paired headset may interfere with the pairing of a car stereo or vice versa.
- What might help: Follow the step-by-step instructions carefully on how to pair. If you’re having trouble pairing, try resetting the Bluetooth settings on both the hearing aid and the device and start the pairing process from scratch. Some devices may have dedicated apps that simplify the pairing process, so consider using those if available.
Finally, it’s also important to remember that the hearing aid use case is more complex compared to streaming with wireless headphones. A set of Bluetooth wireless headphones does not need to use Apple direct streaming to stream audio and a separate app to adjust volume or check the battery status.
In a future post, we’ll discuss LE Audio – the latest generation of Bluetooth audio.
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