Ask Lemmy

As someone who works in live entertainment, Bluetooth is the bane of my existence. Every single show, I get multiple people asking if they can connect their hearing aids to my system via Bluetooth. The issue is that this question comes from a fundamental misunderstanding of how Bluetooth works.

Hearing Assist Systems have a variety of methods. All have their benefits and drawbacks. But notably, the requirement for HAS is that they provide an identical experience to the user as someone who isn’t hard of hearing. And that’s one of the big drawbacks of Bluetooth. Bluetooth introduces lag. HAS typically works either via radio, infrared light, EM loop, or wifi. And only the first three are acceptable for live events, while wifi is more popular for gyms.

The first three HAS all send an audio signal to the user without lag. Radio is a good example because most people understand how they work. The venue has a low power radio broadcaster (because FCC limits how powerful your radio broadcasts can be without an extremely expensive license) in the room, then each user can dial a receiver to that specific band. Then they’re able to plug headphones or a neck loop into the receiver. And boom, you have a distributed HAS with very little effort. Infrared does the same basic thing, with a light transponder instead of a radio antenna. The receivers watch for that light, and send the signal to the headphones. Lastly, EM coil. Many hearing aids have the ability to listen for EM broadcasts. The venue can install a loop around the room, which acts as a giant electromagnet. The hearing aid user switches to that EM mode, and they can pick up that magnetic signal. This is particularly popular in schools, where radio would have a lot of interference from rooms being so close together; The hearing aid user only hears the signal when they’re inside of the loop.

But all three of these have one thing in common: They have zero latency. The hardware to take an analog audio signal, convert it to radio/infrared/EM, and broadcast it, is faster than the time it takes for the audio signal to move from a singer’s mouth to the microphone. It’s nearly instant, because it’s all analog. There is no digitization that needs to take place; Ir’s just converting one type of energy (electrical energy from the audio signal) into other types of energy. And that is easy and cheap to do.

WiFi is popular for gyms, because it introduces a delay in the audio signal. WiFi requires packets, which requires a digital conversion. And that packetization takes time. It’s a processor calculating 1’s and 0’s. But it’s acceptable for gyms, where you’re only listening to a TV mounted on the wall. They can delay the video signal by the same amount, and you’re golden. Now the delayed video signal and the delayed wifi audio are arriving at the same time, so the experience is identical regardless of how you’re listening. But you can’t delay a live event. Shit on stage happens in real time. So WiFi isn’t an acceptable medium for live events.

And Bluetooth is even worse than wifi, because it requires pairing. The Bluetooth protocol requires a handshake between the broadcaster and the receiver, which means it can’t be scaled to larger crowds. Even with the issues of wifi, you can at least broadcast it to an entire room. But for Bluetooth, you would need an individual broadcaster for every single person who wants to connect. It doesn’t scale. It would be like needing to install a new radio antenna for every single person who wants to listen to the radio broadcast. It simply isn’t scalable.

Plus there’s the fact that Bluetooth is a digital system that requires packets just like wifi, which introduces that latency. Even the best Bluetooth systems designed for specific brands (like AirPods being designed specifically for iPhones) have latency. And that’s under ideal conditions. A potential bluetooth system meant for hearing aids wouldn’t be operating under ideal conditions; It would be designed to be compatible with as many different devices as possible, which means you can’t use bespoke programming to reduce latency. And in a venue where you’re hearing both the room noise and the hearing aid, any amount of latency will cause an “echo” effect that makes it completely unusable.

But none of that matters, because I still get annoyed Karens going “but I can connect to my phone, so why can’t I connect to your system?” And even if I bothered explaining all of this, the most I’d get is an entitled scoff.