Just a few years ago, hearing aid technology offered little hope for the profoundly deaf. But now, a biomedical company produces an electronic cochlear implant that bypasses the eardrum and connects directly to nerves in the ear, enabling a profoundly deaf person to hear well enough to discriminate words.
Application Summary
Hearing aids and other types of assistive listening devices amplify sounds so that people with mild to moderate hearing loss can hear better. However, for individuals who are profoundly deaf, even the most powerful hearing aids provide very little, if any, benefit. This is because a profoundly deaf ear typically has damaged or diminished sensory receptors that cannot respond to sound regardless of how loud it is.
A biomedical company set out to develop a cochlear implant to bypass damaged receptors and directly stimulate hearing nerves with electrical current. This device would allow individuals with less than 10 percent word discrimination to experience a significant improvement in hearing.
The cochlear implant involves attaching a microphone to the ear. The microphone picks up audible sounds and sends them to a speech processor that digitizes the sounds using a digital signal processing (DSP) chip inside the ear.
The digitized signal is then transmitted through a wire to a receiver that modifies the digitized signal so that it can be passed on directly to neural tissue. Because every patient's neural tissue is different, each speech processor is programmed for unique processing characteristics during an implant programming session.
During implant programming, an audiologist takes psychophysical measurements and programs the speech processor with the specialized software. Guided by the software and patient's responses, the operator makes adjustments to the processor's thresholds and sets comfortable sound levels.
Development Challenges
Creating the implant's programming software presented a challenge to the biomedical company's engineering team, as the engineers needed a method of collecting numerous waveforms from the implant's stimulator so that critical sound data could be integrated into the software.
Potential Solution
Initially, the researchers attempted to collect waveforms with a digital storage oscilloscope. But the instrument's low channel count and slow speed hindered the team's efforts. In search of a more efficient method of collecting the waveforms, the researchers turned to a portable PC-based solution.
IOtech's Solution
The biomedical company chose the WaveBook, IOtech's 1-MHz portable PC-based data acquisition system. The WaveBook was ideal for capturing waveforms because of the system's ability to collect multiple channels of data. In addition, the system's 16-bit analog-to-digital converter provided the required resolution for accurate harmonic reproduction of the waveforms, which were saved to the attached PC's hard drive and storage disks.
The WaveBook's ability to accurately collect a wide variety of waveforms, including complex, swept amplitude, swept frequency, and any combination of these waveforms was a great benefit. The system's ability to record large data files also was a great benefit, as it gave the test operator the expanded flexibility to experiment with different solutions to ensure that patients would be able to hear all possible audio frequencies evenly.
Conclusion
Using the WaveBook, researchers were able to develop a valuable software program that enables profoundly deaf patients to hear using cochlear implants. With this software, not only are implant adjustments easy to make, but now test operators have the flexibility to experiment with new techniques that may improve each patient's hearing. The WaveBook's memory capability, high-speed acquisition, and PC interface made it an ideal test system.
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