Bluetooth hearing aids receive sound from phones, TVs, and other devices by using a low-energy wireless signal that streams audio directly into both ears simultaneously. The technology works similarly to wireless earbuds, but with protocols specifically designed for the tiny batteries and small housings of hearing aids. Understanding the different standards and how they handle audio streaming, phone calls, and public broadcasts can help you choose the right hearing aids for your needs.
The Wireless Protocols Behind the Connection
Standard Bluetooth, the kind in your car stereo or wireless speaker, uses too much power for hearing aids. It would drain a small hearing aid battery in a matter of hours. Instead, hearing aids rely on Bluetooth Low Energy (BLE), a version of the technology that transmits data using significantly less power. Battery drain during active streaming runs around 3.0 to 5.0 milliamps depending on the product, compared to roughly 1.8 to 2.5 milliamps when the hearing aids are just amplifying sound without streaming. That difference matters when your battery needs to last a full day.
Because standard Bluetooth’s audio profiles weren’t available in the low-energy format, Apple and Google each created their own streaming protocols. Apple’s is called Made for iPhone (MFi), and Google’s is called Audio Streaming for Hearing Aids (ASHA). Both are built on Bluetooth Low Energy and work in essentially the same way: they send a high-quality stereo audio stream directly to both hearing aids at once, bypassing the need for an intermediary device. The result is better sound quality and longer battery life compared to older hearing aids that relied on standard Bluetooth.
How Audio Actually Reaches Your Ears
When you play a podcast, take a phone call, or stream music, your phone encodes the audio and transmits it over the 2.4 GHz radio frequency band, the same frequency range used by Wi-Fi routers and wireless keyboards. A tiny antenna inside each hearing aid picks up that signal. Fitting a 2.4 GHz antenna into something small enough to sit behind your ear or inside your ear canal is an engineering challenge. Manufacturers use miniaturized antenna designs with components placed directly on the antenna traces, which simultaneously shrink the antenna and tune its signal reception without needing a separate matching circuit.
Once the signal arrives, a processor inside the hearing aid decodes it and converts it to sound. Most hearing aids blend the streamed audio with the sound picked up by the hearing aid’s own microphones, so you can still hear the person next to you while listening to a phone call. You can usually adjust the balance between streamed audio and environmental sound through a companion app on your phone.
Connection Range and Signal Stability
Most Bluetooth hearing aids use Class 2 radios, which have a functional range of about 30 feet. That’s enough to keep a connection while your phone sits on a kitchen counter and you walk around the room, but the signal can drop if you leave your phone upstairs or on the other side of a large house. Walls, furniture, and other wireless devices can shorten that range further. If you’ve ever had a wireless earbud cut out briefly in a crowded area, the same interference applies to hearing aids.
Phone Calls and Hands-Free Use
One important limitation of the MFi and ASHA protocols is that they are one-way streams. They send audio from the phone to the hearing aids, but neither protocol originally supported sending your voice back through the hearing aid’s microphone. That meant you still had to hold your phone near your mouth or use a speakerphone during calls.
Newer hearing aids have changed this. Some models now support true hands-free calling by using the hearing aid’s built-in microphones to pick up your voice and transmit it back to the phone. This currently works most reliably with iPhones and iPads, and it typically needs to be enabled in your device’s accessibility settings. For Android phones or older hearing aids that don’t support this feature natively, manufacturers offer small clip-on accessories that act as an external microphone, temporarily turning the hearing aids into a full wireless headset.
Audio Delay During Streaming
When hearing aids process sound from their own microphones, the delay is just a few milliseconds, fast enough that you’d never notice. Bluetooth streaming introduces more lag. Wi-Fi and Bluetooth audio can add delays of up to hundreds of milliseconds, which becomes noticeable when you’re watching video. If the audio arrives even 100 milliseconds late, lip movements fall out of sync with speech.
Newer Bluetooth Low Energy Audio standards are expected to reduce this delay, though not quite to the level of a hearing aid processing sound in real time. For most phone calls and music listening, the lag isn’t perceptible. For video, many phones and TVs compensate by delaying the picture slightly to match the audio, but your experience will vary depending on the app and device.
Auracast and Public Audio Broadcasting
A newer technology called Auracast is poised to change how hearing aid users experience public spaces. Auracast allows a single transmitter to broadcast audio wirelessly to an unlimited number of compatible listening devices within range. Think of it like a public Wi-Fi network, but for sound. In a theater, airport, or house of worship, an Auracast transmitter connects to the venue’s sound system and broadcasts the audio over Bluetooth Low Energy. You select the stream on your phone or smartwatch, and the audio routes directly to your hearing aids.
The system doesn’t require pairing your device ahead of time. You simply scan for available streams, much like choosing a Wi-Fi network, and connect. Venues can broadcast multiple streams simultaneously, offering the main audio alongside options like language translations or audio descriptions. Auracast uses a newer audio format that delivers clearer sound with less delay than classic Bluetooth, and because it streams directly to compatible hearing aids, cochlear implants, or earbuds, it replaces the clunky loop systems and FM receivers that public venues have used for decades.
What Determines Compatibility
Not every Bluetooth hearing aid works with every phone. MFi hearing aids are designed for Apple devices and connect natively through the iPhone’s accessibility settings. ASHA hearing aids work with Android phones running Android 10 or later, though the quality of the connection can vary between phone manufacturers. Some hearing aids support both protocols, giving you flexibility if you switch phones.
The newest generation of hearing aids built on Bluetooth Core Specification 5.2 or later support the Hearing Access Profile, an industry standard designed to make hearing aids interoperable across brands and devices. This is part of the broader LE Audio standard and is intended to reduce the fragmentation between Apple-only and Android-only solutions. As more phones and hearing aids adopt this standard, the pairing process should become as simple as connecting any other Bluetooth accessory.
If you’re considering Bluetooth hearing aids, the most practical thing to check is whether the specific model supports your phone’s operating system. Your audiologist or hearing aid provider can confirm compatibility, and most manufacturer websites list supported devices.