Last month I wrote some details about our brain’s function in the hearing process. Here are the foundational comments from my August article. “Acoustic energy vibrates down the ear canal against the ear drum, it is then changed into mechanical energy as it passes through the three small bones of the middle ear. Next it becomes hydraulic energy in the fluid fill tubes of the inner ear, the cochlea. Finally the sound wave as it moves through that fluid flows over microscopic inner hairs which change it into electro-chemical-neural energy signal that flies up the auditory nerve into the complex receivers waiting in the brain. The brain can make no sense of the sounds of life and relationships without the signals being properly processed into it. By the way, the four sound energy transitions happen in a millisecond. Your ears and brain work together as a system, with your brain doing most of the heavy lifting. Your brain uses the information from your two ears to orient for you by figuring out which direction sound is coming from. It is in the brain that sound waves become sounds that you recognize, and it is your brain that provides focus so you can separate unwanted noise from conversation. Right now, all four of those tasks are happening simultaneously and continuously inside your brain.”
Modern hearing aid technology, research and development, uses this brain-ear system importance as the guiding factors to create instruments that help the brain. A large segment of hearing aid research and development pushes the concept that the more channels or bands in the hearing aid circuit the better outcome for the patient. The things that factor into patient outcomes related to increasing the number of bands and channels are many, and the conclusions drawn by studies that have investigated the effect of band and channel numbers on patient outcomes are, at best, not conclusive. Because increasing numbers of channels and bands is an accepted fact of more advanced technology, sometimes for marketing and higher price justification, it is worthwhile to see what the actual research suggests at this time.
Jason Galster, PhD wrote, “Research in the area of channels or bands in a hearing aid's programming software, suggests that that seven channels are sufficient to shape a frequency response to match prescribed targets for most configurations of hearing loss. In addition to number of bands, a range of studies have investigated the impact that increasing the number of channels has on restoration of audibility and speech recognition ability. These studies suggest that hearing aids with as few as eight channels offer sufficient frequency resolution to restore audibility, even in listening conditions with background noise. Hearing aids offering fewer than eight channels may not offer sufficient frequency resolution to restore audibility of speech in the cases of particular hearing loss configurations and stimulus types.”
The Veterans Administration also did a major study with 1,500 hearing impaired patients and concluded that “speech discrimination or word recognition did not increase above eight channels in a hearing aid circuit.” The manufacturers will argue more channels equal better audibility, but audibility is hearing the sound while discrimination actually understands the words.
The brain needs certain information to understand speech and sound location. Modern hearing aids have amazing ability to do just that but it is not connected to having hundreds of channels. Most aids today come with 18, 32, or even 64 channels. I used the “more channels is better” reasoning for many years until further research began to show that increased number of channels will allow the circuit to do more astounding and needful internal computer processing things, but do not guarantee the brain will understand better.
Hearing care is health care. If you have the symptoms of hearing loss let a professional help you find out why. The hearing professional will help you sort out the technology level to meet your need, your budget, and answer your hearing need questions.