Smart application improves hearing implants
An Antwerp University researcher has developed a cloud-based application that means a major leap forward in the fine-tuning of electronic hearing devices
A near-perfect ear
Compared to all our other senses, our hearing is probably our most important sensory organ. Hearing is essential to humans’ existence. Hearing impairments run through all segments of society and can manifest themselves at different phases in people’s lives: They can affect people as they grow old or they can develop with an injury, while others are born with them.
The cochlear implant is the first technological development that offers a radical breakthrough for patients with severe sensory disabilities. As rudimentary and subpar to the healthy human ear as the cochlear implant may currently be, it has already proved essential for the social integration, communicative abilities, and comfort and happiness of people with hearing disabilities.
A cochlear implant operates in a different manner from traditional hearing aids. They provide direct stimulation of the auditory nerve in the cochlea inner ear structure, bypassing all the damaged parts of the ear, while a hearing aid only enhances the sound signals entering the inner ear.
In other words, a cochlear implant doesn’t directly deliver sound, but electrical signals that are transported to the auditory nerves. Its external speech processor – usually worn behind the ear – picks up sounds from the environment and converts them into a digital signal.
But because a cochlear implant stimulates between five and 25 little hairs connected to the auditory nerves in the cochlea, the electrical signal has to be fine-tuned very precisely.
“There are around 100 parameters that can be adjusted,” says Bart Vaerenberg, who wrote his PhD at the University of Antwerp on the fine-tuning process or “fitting” of cochlear implants.
Most of these parameters relate to the amount of electrical current delivered to the electrodes and to the signal processing strategy, or how sound is transformed into a digital, electrical signal.
It’s a major hurdle to find the best parameters for each implant recipient
“It’s still a major hurdle for audiologists to find the best set of parameter values for each cochlear implant recipient,” Vaerenberg says. “To determine which set of parameters is better, the recipient’s hearing is assessed psycho-acoustically in different domains such as audibility thresholds, loudness growth function, spectral discrimination, and ultimately, speech understanding. This is called the outcome and it is assessed repeatedly over time.”
During his research, Vaerenberg developed a new software application that assists audiologists during this cochlear implant fitting procedure. This “intelligent” FOX app – the name is a reference to the FOXP2 gene that plays a key role in speech and language development – inspects the current parameter values of the recipient’s cochlear implant processor and determines how his or her hearing can be improved, based on the deficits observed.
The remarkable thing about FOX is that it’s a cloud-based application, which means that it’s capable of learning from the individual cases offered by the entire community using the application. “This allows the system to constantly improve over time,” says Vaerenberg.
A more objective approach
Until now, the fitting process has been performed manually by adjusting the parameters in accordance with the patient’s feedback.
“This is by definition a subjective approach, usually targeted at auditory comfort – ‘does this sound more pleasant or not?’ and often not in line with a recipient’s auditory performance as it would be expressed through psycho-acoustical measurements,” Vaerenberg says. “The use of FOX ensures a systematic approach that drives the recipient towards maximal performance.”
The parameters of the cochlear implant moreover need to be readjusted over time, which is a consequence of adaptation and learning effects. This underlines the importance of Vaerenberg’s application.
The FOX system is already available for the Advanced Bionics implant system, one of four global cochlear implants manufacturers, and it will become available through market leader Nucleus soon.
Vaerenberg is currently working at Otoconsult, a Flemish consultancy firm focused on professional audiologists. He performed his PhD research under the umbrella of a Baekeland mandate – named after Leo Baekeland, the Flemish-American inventor of Bakelite. This is a formula in which a private company gets financial support from the Flemish government agency for Innovation through Science and Technology if it “adopts” a doctoral researcher.
Photo courtesy Otoconsult