Evidence shows that classic Bluetooth is not Made For All places
Since the introduction of the Made for iPhone and Bluetooth Low Energy protocols a hive of activity has been taking place among hearing aid manufacturers as they strive to integrate direct streaming technology into their hearing aids.
The technology offers two main benefits: lower energy consumption to provide longer battery run times and most importantly a way to stream audio signals directly to the hearing aids without an intermediate device.
As the name suggests, Made for iPhone was developed for Apple iOS devices and therefore direct streaming was restricted to this group of devices. Android users still need to rely on inconspicuous relay devices to enjoy streaming to their hearing aids.
Although an industry body called the Bluetooth Special Interest Group has announced that a Made for Android protocol* is under development, until recently the only option for directly connecting Android devices to hearing aids was the Bluetooth Classic protocol. Even so, Bluetooth Classic was discounted by many hearing aid manufacturers because it consumes significantly more power than the Made for iPhone technology. Another disadvantage was that Bluetooth Classic could only be connected to one device at a time, which meant only one hearing aid could receive a streaming signal. However, hearing aids are usually fitted to both ears, so a simultaneous Bluetooth connection to both sides would offer a far better streaming experience.
The challenge of delivering high-quality streaming in the real world
A well-known hearing aid manufacturer has chosen to integrate Bluetooth classic into their hearing aids in a bid to win the Bluetooth technology race. They have introduced a novel approach to solve the issue of providing a streamed signal to both hearing aids, despite Bluetooth Classic’s limitation of only being able to connect to one hearing aid.
To investigate the performance of Bluetooth Classic for hearing aids, Signia undertook a detailed study to ascertain whether this approach satisfies the needs of hearing aid wearers. The results of this study reveal a significant limitation: These devices fail to deliver a fundamental requirement of hearing aids with direct streaming, which is to stream an unbroken high-quality signal into the patients’ ears in a variety of real-world wearing environments.
The fundamental drawback of their approach is that they rely on a 2.4 GHz signal to transfer information between the hearing aids. The technical characteristics of the signal means that it is inefficient to transmit the signal in a straight line between both ears. Instead, the 2.4 GHz signal relies on reflections from walls and other hard surfaces when it’s transmitted from one hearing aid and received by the hearing aid on the opposite ear.
Provided there are hard surfaces in the wearer’s immediate vicinity then the signals are transmitted successfully between the ears and the wearer enjoys a continuous high-quality streamed signal. The problem arises when there are no hard surfaces such as walls and ceilings to facilitate transmission between the ears, such as in large halls or outdoor spaces. The study revealed that while Bluetooth Classic hearing aids performed well in indoor environments, in outdoor situations the performance fell well short of our threshold of acceptable streaming stability. For many participants in the study, the devices were frustrating to use in some environments.
A novel technology that fails to convince
In summary, while the introduction of this technology is a novel approach to increase compatibility amongst smartphones it fails to offer a high-quality unbroken streaming experience for wearers in a variety of real-world situations. Wearers can experience a good streaming experience indoors – at the hearing care professional’s office, at home, or at work for example – but they will inevitably be disappointed by the performance while commuting, walking, running and generally enjoying the outdoors with streamed music or phone calls.