A new tool and method for achieving deep-canal impressions and devices

A new micro-in-the-canal hearing aid has been designed to satisfy patient desires of simplicity, comfort, and cosmetics. A field study using the device also suggests it provides exceptional sound quality and first-fit acceptance by patients, and ease of fitting for dispensing professionals.

Patients want invisible, comfortable hearing aids that are easy to use, and they routinely demand hearing aids that have excellent sound quality and speech-in-noise discrimination. Clinicians need proven solutions.

Becky Finlen, AuD, is manager of clinical product development at Phonak Inc, Warrenville, Ill. Correspondence can be addressed to HR or Dr Finlen at

With continued advancements in digital technology, the focus on sound quality, size, feedback suppression, and speech understanding in noise has provided significant benefits for many patients. Consumers continue to be conscious of cosmetics, simplicity, and comfort when pursuing amplification.

This article focuses on these concerns and proposes a solution for uncompromised sound quality through a fully featured, comfortable, custom-made hearing device called the Phonak nano. To validate the product, a field study was conducted to assess how the new device performs relative to these patient needs.

Simplicity. Moria1 referenced a survey of 300 people with hearing loss who had not purchased hearing aids, indicating that 82% of the respondents wanted to purchase discreet hearing devices, while 73% of the respondents were looking for no frills or accessories. Most patients are looking for simplicity and invisibility as the primary influences in their buying decision.

Simplicity comes in many packages. Some individuals do not want manual adjustments; they just want to wear it and go. In addition, hearing aids should adjust to most environments and provide the best sound quality. MarkeTrak V2 revealed the top-10 reasons for “in the drawer” hearing aids. The survey indicated one of the top-10 reasons is the frustration of manipulating a volume control. These patients also desired a “smart” hearing instrument that adjusted to the dynamic environment.

Figure 1. Styles of custom ITEs sold, 2008-2011, according to HIA year-end statistics.5

Figure 2. Phonak Lyric.

Figure 3. Phonak Nano.

Comfort. Beyond simplicity, comfort is also crucial. The MarkeTrak V data2 revealed that poor comfort was the number-3 reason for hearing aids to be placed “in the drawer.” Of the 907,200 respondents, 170,000 complained the devices hurt, fell out of their ears, or were uncomfortable to wear.

Building a custom shell for a discreet device that fits each unique ear is definitely an art. Understanding the contours of the ear via the impression is still challenging. Although taking an ear impression is really a straightforward process and not complicated, the impression remains the foundation to any successfully fit device. The technique and materials used can influence the result of the impression and comfort of the final custom device.

Chester Pirzanski3 has written extensively in HR about the best techniques for taking an impression for fewer remakes and optimal fittings. One of the most important steps of this technique is to place the oto-block just past the second bend and fill the ear completely. This allows the manufacturer to detail the impression correctly and determine how much to taper the tip of the canal, the most sensitive area, while maintaining an adequate fit.

Cosmetics. Cosmetics are another large factor for patients concerned with the size and appearance of the instruments. As hearing care professionals, it is important to understand the client and what satisfies them aesthetically in addition to providing a measurable improvement to their hearing loss. As stated in the HR Interviews with Sergei Kochkin,4 the benefit of a completely-in-canal (CIC) form factor to the consumer is less visible, and customers are still satisfied with the design and look of the CIC. Patients feel different about themselves when they are wearing a hearing aid; therefore it is important to understand what motivates each patient and provide an appropriate solution.

The CIC continues to gain traction in the market with the addition of a new emerging micro-in-the-canal (MIC) category. Figure 1, compiled from 2011 Q4 data published by Hearing Industries Association (HIA), suggests the market is responding positively to this nearly invisible option. CICs continue to increase in popularity, and the style split between custom, standard behind-the-ear (BTE), and receiver-in-canal (RIC) is nearly equal portions in the market.

Figure 4. Average audiograms of participants shown on the fitting range of nano.

The Phonak Lyric® instrument (Figure 2) is a pioneer in the extended-wear category with a 100% invisible product designed to be worn 24/7. Lyric is inserted by a certified hearing care provider and is placed in the ear for up to 4 months. For patients who contraindicate for Lyric, the emerging micro-in-the-canal (MIC) category is a viable option.

The Phonak nano (Figure 3) is a MIC product, brought to market based on the latest generation digital processing platform. The nano is designed to offer exceptional sound quality and user-friendly automatic sound adjustment technology in a discreet package that is comfortable to wear with high retention. It was specifically designed to meet the needs of the market relative to simplicity, comfort, and cosmetics.

The nano is approximately 20% smaller in volume than the previously smallest Phonak CIC hearing aid. The MIC requires a standard, good quality CIC impression per recommendations by Pirzanski.3 No deep impressions, special techniques, or materials are required. The nano is available in the Ambra and Solana product lines with similar features and performance. To maintain the device’s small size, the remote control and wireless features are not available with this product. The device is almost invisible when worn, with the faceplate typically recessed to the first bend.

Each nano is custom-crafted using a completely digital design process and the latest material science. Thinner shell walls, a new faceplate, and battery door design, and other innovations allow for optimum component positioning, resulting in a device that sits deeper in the ear canal with the faceplate at the first bend. A tapered tip prevents contact with the bony portion of the ear canal for enhanced wearing comfort.

The device is not intended to be placed at the bony portion of the ear canal. However, the tip may extend into this area, eliminating the need for a special impression technique. Because the microphone is recessed farther into the ear canal, a new algorithm was designed to compensate for the resulting shift in frequency response.

Figure 5. Phonak nano (in gray and blue) versus a standard CIC.

Figures 6a-b. Size (top) and design (bottom) comparisons of the nano compared to a standard CIC shell (n=51).

Device geometry data are also transferred to the Phonak Target fitting software for an optimized first-fit result that facilitates spontaneous acceptance. The sound quality of the instrument is addressed through the chip design and the acoustic characteristics using Acoustically Optimized Venting (AOV). The nano shells have a thinner wall thickness to accommodate the electronics. In order to make the shell durable, a new shell material, which incorporates ceramic-like fillers specially adapted from the dental industry, was designed to achieve added shell stability and durability.

To confirm that the nano product met all of the ambitious design goals, it was critical to fit a large number of patients internally at Phonak and at independent hearing practices. The results of the Ambra nano field study are detailed below.

Field Study

Participants. A total of 51 patients participated in the Ambra nano field study, which ran from October 2011 to December 2011. Of those patients, 29 were male and 22 were female, and the average patient was 64.2 years old. All patients were selected through their experience level with hearing aids: new user, CIC or RIC wearer, and possible Lyric contraindication due to size of their ear canal.

Only patients with a bilateral, normal-sloping to moderately severe sensorineural hearing loss were selected to participate. The average audiogram of the participants, as well as the fitting range for the nano MIC (in light green), is shown in Figure 4, demonstrating a wide range of acceptable thresholds available for candidacy.

Of the 51 patients, 16 had previously wore a receiver-in-canal (RIC) BTE, 17 wore CICs, 17 were new users, and 1 patient had purchased a 1-year Lyric subscription but had trouble with fit due to size of the ear canal. The experience level for the participants varied, with the majority of participants representing either a “new user” or “more than 6 years” category.

Of the 51 patients in the study, 22 were contraindicated for Lyric due to ear canal size. All were successfully fit with Phonak Ambra nano, the company’s smallest custom product. The nano is designed with the faceplate positioned at the first bend. The individual geometry of the ear canal and entrance of the canal determines the placement of the faceplate, and therefore some patients were provided a nano with the faceplate located between the first bend and the entrance of the canal. Figure 5 shows the Phonak nano (in gray/blue) versus the standard CIC (in yellow) in an ear canal.

Procedure. Five dispensing offices located across the United States participated in the study, accounting for 41 of the 51 patients; the remaining 10 patients were fit internally at Phonak (Chicago area). Each dispensing professional obtained 8 or more people who met the selection criteria. The clinician was required to take an adequate CIC impression, which encompassed the full ear geometry and extended just past the second bend to allow fabrication of the most appropriate nano device for each ear.

Figure 7. Sample picture of nano (left) and standard CIC (right) in the same ear.

An audiogram and previous wearing history were obtained prior to the start of the study. Each patient was scheduled for three appointments to undergo an evaluation of the overall fit, sound quality, and spontaneous acceptance. The participants were fit with both an Ambra nano and a CIC style (without components) for size and design comparison. In addition, questionnaires were completed during the appointments and at home during the study period. The dispensing professional completed the patient fitting questionnaires during patient visits. The professionals also completed a questionnaire to obtain information about their perceptions of the fitting.

Of the original 51 patients who participated, 3 dropped out of the study after the first appointment due to time commitments. Data were captured during the first appointment for all patients.


Acceptance. Several subjective measures were obtained during the initial fitting and home trials. It was important to have patients rate overall appearance and first-fit sound quality prior to any adjustment to the hearing aid. Questions relating to the size and design of the devices (compared to a CIC without electronics) were asked within 5 minutes of the initial appointment (randomization was done for the questions relating to the shell styles). Ratings were obtained for first-fit acceptance of overall sound quality and comfort of the nano devices, with average spontaneous acceptance of 80.4%. The “new user” or “previous user” categories equally accepted the initial fit of sound quality and comfort of the instruments.

Figures 8a-b. Comfort and retention ratings at initial fitting.

When evaluating the size of the instruments, participants were asked to hold both the nano and the CIC devices in their hands. The clinician asked how they would rate the size of each device using the rating scales listed in Figure 6. A total of 85% of the patients indicated the nano was “small” or “just right,” while 53% of the participants indicated the CIC met those same standards. Instrument design was evaluated the same way, using the rating scale listed in Figure 6b. In this case, 78% noted that the nano was “very appealing” or “appealing,” while 55% noted the same for the CIC. Therefore, in a side-by-side comparison, some patients did notice a positive difference in the size and design of the nano.

Figure 7 shows pictures of the nano compared to the standard CIC for one participant at 90º viewing angles. The standard CIC is just visible at the entrance of the canal, while the nano device is hidden behind the tragus and is nearly invisible.

Fit. Participants were asked to rate the comfort of the nano device once inserted into their ears during the initial fitting. The comfort and retention of the devices were two of the main focuses of this new form factor. A total of 92% of the participants indicated the nano device was comfortable at the initial fitting. In addition, it was rated as having good retention by 98% of the participants during the initial fit (Figure 8).

To determine the visibility of the devices, the participant’s family or friends were asked to rate how visible the devices were in the ear from the front (0º) and from the side (90º). In nearly all circumstances (93%), the devices were “not” visible from the front. When family members or significant others were asked if a nano was visible from the side, less than 10% reported it to be visible. More than 80% reported that the aid was not visible or that only a bit of the aid was observed, which supports the nano’s near-invisibility claim. As previously identified with the size and design outcomes, the nano was invariably the smallest custom product modeled for each participant.

Sound quality. Participants were asked about the sound quality of the fitter’s voice and their own voice. The results yielded a rating of 100% “acceptable” for the first-fit sound quality of the fitter’s voice and 76% “acceptable” sound quality for the patient’s own voice (Figure 9). The dispensing professionals then had the opportunity to make adjustments to the devices.

During the study, each clinician tested participants in an unaided and aided test setting for soft speech (in quiet) at 50 dBSPL. Figure 10 shows there is a wide range of variability for the unaided soft speech at 50 dB, with the mean at 57.8%. Aided scores yielded improved performance among participants with a mean of 86.6%. Therefore, patients demonstrated excellent understanding of soft speech as shown by good discrimination ability.

Figure 9. First-fit sound quality rating prior to fine-tuning adjustments.

Figure 10. Speech discrimination scores of soft speech (50 dB) in quiet in soundfield.

Figure 11. Dispensing professionals’ perceptions of impression-taking technique required for nano.

Results from Clinicians

It was important to provide questionnaires to the participating hearing care providers to see how they rate the new MIC form factor. The dispensing professionals indicated that they were not challenged by taking a good standard CIC impression as required for the nano device (Figure 11). Since the impression-taking technique is not a new process, providers should be comfortable obtaining the impression and not have concerns about selecting the nano as an option for patients.

The clinicians were also asked how they perceive the size and design of the nano MIC form factor for each patient. The size of the nano was perceived as “small” or “just right” by 92% of the clinicians; the design was rated as “very appealing” or “appealing” by 87% (Figure 12).

Figures 12a-b. Dispensing professionals’ perceptions of size and design of nano.


The new MIC form factor, as utilized in the Phonak nano, is customized for each patient and designed to provide a discreet fully featured comfortable hearing device. This study indicates that the participating patients rated the nano highly for spontaneous acceptance of the sound quality, design, size, and comfort.

Participating care professionals in the study found the new device to be an appealing and easy-to-fit hearing solution. The Phonak nano is specifically designed for patients wanting a nearly invisible comfortable hearing aid with uncompromised sound quality.


The author thanks Amy Jachim, AuD, from Phonak for her assistance with the test protocol and data collection. In addition, Phonak thanks the five customers for participating in the study: Aberdeen Audiology; Associated Hearing Pro, LLC; Geneva Hearing; Kaczmarski Hearing; Pacific Hearing Inc.

  1. Moria A. Four transformative patient demands: convenience, size, simplicity, and flexibility. Hearing Review. 2011;18(4):36-42.
  2. Kochkin S. MarkeTrak V “Why my hearing aids are in a drawer”: the consumer’s perspective. Hear Jour. 2000;53(2):34-41.
  3. Pirzanski C. Earmolds and hearing aid shells: a tutorial part 2: impression-taking techniques that result in fewer remakes. Hearing Review. 2006;13(5).
  4. Strom KE. HR Interview…Sergei Kochkin. Hearing Review. 2005:12(10):24-32, 82.
  5. Hearing Industries Association (HIA). HIA quarterly statistics report, 4th Quarter 2011 Statistics; 2012.

Citation for this article:

Finlen B. Improved Hearing with a New Discreet Micro-in-the-Canal Hearing Instrument Hearing Review. 2012;19(04):28-33.