Lyric is a unique hearing device designed to incorporate the advantages of both deep canal placement and extended wear. Deep canal placement provides many acoustic and cosmetic advantages, widely discussed with the advent of deep-canal CIC hearing aids in the 1990s1-6 and in a previous article about this device.7 Lyric remains in the ear canal 24 hours a day for up to 4 months at a time, creating a new category of hearing device and providing patients with a unique amplification experience.
|This article was submitted to HR by Tanya L. Arbogast, ScD, a research audiologist at InSound Medical Inc, Newark, Calif. Correspondence can be addressed to HR or|
The Lyric design and same-day sizing/fitting method are designed to allow for comfortable, deep-canal placement without deep ear canal impressions and without the need for the patient to fuss with the device(s) on a daily basis. This article describes patient candidacy and fitting protocols for the Lyric device.
Features of the Lyric Device
Basic features of Lyric are briefly described here (for more detail, see Arbogast and Whichard7). Figure 1 illustrates the components and placement of Lyric in an ear. Lyric is sized specifically for each ear and is available in 5 seal size combinations. Devices are stocked on the shelf for same day sizing and fitting. The seals are compliant, breathable, biocompatible, and designed to hug various shapes and sizes of ear canals for comfort while preventing feedback and migration. A moisture and cerumen repellent cap protects the internal components.
|FIGURE 1. Illustration showing the Lyric device and its placement in the ear canal.|
The sound processor is a single-channel, analog, wide-dynamic-range-compression (WDRC) circuit. The proprietary battery is designed and shaped to fit comfortably deep in the ear canal and to last up to 4 months. A flexible joint between the two seals accommodates the curvature of the ear canal.
Lyric is approximately 16 mm long and sits 4 mm or more inside the ear canal. The receiver delivers sound approximately 4 mm from the tympanic membrane. The placement of both microphone and receiver deeply in the ear canal allows optimum analog sound processing.
Lyric candidacy falls into four main categories: lifestyle, fitting range, medical history, and ear geometry.
Lifestyle. Patients who have been successful with Lyric come from all walks of life and range in age from 9 to 100. Almost all lifestyles are compatible with Lyric. However, it is not recommended for avid scuba divers or sky divers.
Fitting range. Lyric accommodates any type of hearing loss in the mild to moderately severe range (Figure 2), from flat to sloping.
Medical history. Although the greatest advantages of Lyric are its deep-canal placement and extended wear nature, these features preclude some patients from wearing the device.
|FIGURE 2. The Lyric fitting range is from mild to moderately severe.|
The outer and middle ear should be healthy. People with ear canal conditions (growths, skin conditions, recurrent otitis externa) or extremely thin, dry skin are typically not candidates. Middle-ear conditions that are not compatible with Lyric include tympanic membrane perforation, PE tubes, cholesteotoma, and chronic/recurrent otorrhea.
Medical issues requiring contraindication are any history of radiation therapy to the head/neck, cognitive abilities insufficient to understand the device, and TMJ disorder with otalgia. Medical clearance from a managing physician is recommended when the candidate is on prescription anti-coagulation therapy, has an immune disorder or uncontrolled diabetes, or has undergone chemotherapy within the last 6 months.
Ear geometry. Approximately 50% of ears are of a size and shape that can accommodate the first-generation Lyric. A new version of Lyric that will accommodate more ears is currently in development and scheduled for introduction in 2011.
The most common geometrical issues are canals that are too narrow and/or short. Other less common contraindications include a significant step-up in the canal floor, extreme v-shaped canal, or a large bulge in the canal. Fitting patients who are indicated for Lyric produces a high chance of successful wear. Contraindicated fittings increase the chance of discomfort and/or return for credit.
Ear Canal Visualization: A Critical Component in Deep Canal Fittings
Examination of the entire external auditory canal is critical to successful Lyric fittings—for both new fittings and device replacements. Examination allows the clinician to determine the need for cerumen management, evaluate ear health, and assess the shape of the ear canal relative to candidacy.
Appropriate equipment for canal visualization is imperative when working deeply in the ear. As such, an otoscope is not ideal due to relatively poor lighting and limited visual field. Although the initial learning curve may be steep, a microscope allows for excellent lighting and visualization, along with variable magnification levels (see McHugh and Traynor8 for an overview of the benefits of video otomicroscopy).
However, many successful Lyric practitioners use high-quality loupes with headlight and premium video otoscopes. An equipment upgrade increases patients’ perception of professionalism and it benefits all patients; these tools can be used to improve the examination of any ear canal, to perform cerumen management on any patient, to create excellent impressions, and to educate patients and their families.
Fitting of the Device
Lyric can be sized and fit in one office visit that takes approximately 1 hour. Device replacement visits take approximately 10 minutes. The procedure is fairly simple and routine but does require special training and practice.
Sizing. Fitting Lyric on a new patient begins with the sizing procedure. The goals of sizing are to determine if the ear canal can accommodate the device and, if so, the maximum insertion depth and appropriate seal sizes.
|FIGURE 3. Illustrations of the sizing tools.|
Sizing consists of two steps: 1) length sizing and 2) lateral seal sizing. The length sizer is a thin tube with a very soft, flexible tip (top of Figure 3). The sizer is inserted into the canal until the soft “noodle-like” tip touches the tympanic membrane. The clinician feels the touch in the recoil of the sizer. Because the tip is soft and flexible, there is no pain associated with this procedure. The length of the canal is measured by referencing the posterior canal opening with the color bands on the sizer. This determines if the ear is long enough for Lyric and the maximum Lyric insertion depth.
The lateral seal sizer comes in three sizes: small, medium, and large (lower part of Figure 3). The clinician starts with a small sizer, moving up in size depending on the results. The lateral sizer is placed at the appropriate insertion depth using proprietary slider forceps designed for placing lateral sizers and devices at a specific depth. The fit of the seal around the circumference of the canal is assessed. The presence of gaps indicates the need for a larger size, while a tight fit and/or folds/bunching in the seal indicates the need for a smaller size.
Ears may be contraindicated for too narrow if the small sizer is too large (more common) or for too large if the large sizer is too small (less common). The best-fitting lateral seal size is determined, and then the medial seal size is deduced based on the lateral seal size and canal shape assessment.
Placing and programming in the ear. The correct device size, determined during sizing, is programmed with the HandFit® wireless programming system. A computed program is calculated based on the audiogram. Five parameters can be adjusted by the clinician either before placement or in situ: soft level gain, low frequency cut, volume, max volume, and high-frequency boost.
The ear canal is lubricated and the device is slowly inserted to the appropriate insertion depth using the slider forceps. The clinician uses the measured maximum insertion depth from sizing, patient feedback, and the feel of the insertion to determine the best placement. Once it is placed, the clinician turns the device on with the SoundLync® magnet and adjusts the program if necessary.
Lyric Removal and Re-Fit
Lyric can be removed by a clinician, patient, or loved one at any time, usually when the device stops functioning. The SoundLync contains a removal tool or a blunt-nosed tweezer can be used. Once removed, it can be replaced only by a trained professional.
Re-fit office appointments are typically 10 minutes, at which time the patient receives an entirely new Lyric device; the battery is not changed in the removed device (ie, devices are not refurbished). On average, patients can expect 5 to 6 re-fit visits per year, and whenever there is an upgrade in technology, the patient receives the newer technology at their next re-fit. In between re-fits, patients enjoy hearing 24/7 without having to fuss with or maintain their hearing device.
Fitting the world’s first and only extended wear hearing device requires a uniquely specialized sizing and fitting process, without the need for deep canal ear impressions. The Lyric sizing and fitting process is a proven technique that is both safe and comfortable. It has been used by hundreds of hearing professionals on thousands of patients.
Like all hearing devices, Lyric is not for everyone; patient selection is key to maximizing success and satisfaction. Fitting appropriate patients leads to excellent outcomes for both patient and clinician.
- Killion MC, Wilber LA, Gudmundsen GI. Zwislocki was right… Hearing Instruments. 1988;39(1):14-18.
- Agnew J. Acoustic advantages of deep canal hearing aid fittings. Hear Instrum. 1994;45:22-25.
- Gudmundsen GI. Fitting CIC hearing aids—Some practical pointers. Hear Jour. 1994;47(11):10, 46-49.
- Staab W. Introduction to deep canal principles. Sem Hear. 1996;17(1):3-20.
- Mueller HG, Ebinger K. CIC hearing aids: Potential benefits and fitting strategies. Sem Hear. 1996;17(1):61-80.
- Chasin M. CIC Handbook. San Diego: Singular Publishing Group;1997:69-81.
- Arbogast TL, Whichard S. A new hearing aid class: the first 100% invisible, extended-wear hearing aid. Hearing Review. 2009;16(4):20-26.
- McHugh GR, Traynor RM. Video otomicroscopy: a new “vision” in cerumen management. Hearing Review. 2009;16(5):14-20. Accessed July 30, 2010.