Q: The more I look, the more I see, (or just barely see), people wearing the small, behind-the-ear hearing aids. I could probably get my mother to wear them if they would work for her, but she has been told they wouldn’t. Are there any that might?
The popularity of open fit products has increased significantly over the past 5 years. Although other factors (eg, directional microphones, improved cosmetics related to BTEs) may have played some part, the increase can be mostly attributed to the popularity of open fit products among dispensing professionals. Two of the most significant reasons for this are the ability to receive them faster, since there is no customization, (i.e. no earmold or ear impression), and the relative ease there is in fiiting them –
Every major poll of hearing professionals over the last 4-5 years has shown a preference for fitting Open Fit products. The main reason for this is likely the fact that acceptance of hearing instruments is higher for those fit with Open Canal style instruments; there are several reasons for this, but the two most common are the cosmetics, they are significantly less obvious, and a distinct difference in the occlusion effect, which is what causes many hearing aid wearers to hear their own voice louder than they have in the past.
Although popularity within the Hearing Instrument Professional community does not equate to product effectiveness in everyday listening situations, there is some evidence suggesting that OC wearers enjoy some unique advantages, specifically better sound quality of their own voices, better localization, and improved cosmetics. Another study suggests that, for the proper candidate, there may be no downside to fitting OC products.
Given that OC products enjoy widespread popularity, the focus of recent some studies was to investigate whether OC products have any inherently unique problems in their design or use, (Berkely and Taylor, 2007).
There does, however, appear to be a potential downside to OC products.
There is both laboratory and real-world evidence that suggests OC products have some unique features that make them a superior choice for some patients. Additionally, a number of studies have concluded that there is no downside to fitting OC products on properly selected candidates. Although these statements are supported by evidence, this study indicates there are some potential problems with OC products, possibly contributing to lower than expected patient satisfaction.
1. Problems associated with occluding cerumen and acoustic feedback, while perhaps not as common in OC products, continue to be the major causes of lower than expected patient satisfaction, from the viewpoint of dispensing professionals.
2. Ineffectiveness in noise was reported to be more common in OC devices than in non-OC devices. This finding, although not entirely unsurprising, warrants further discussion. Given the large venting, the directionality of OC devices is confined to frequencies above 1500 Hz.5 This lack of directivity below 1.5 kHz may explain why speech understanding in noise is one of the leading factors contributing to lower than expected satisfaction. Dispensing professionals need to be aware that OC products may not offer their patients optimal signal-to-noise ratio improvement.
3. Another factor contributing to lower patient satisfaction for OC users compared to their non-OC counterparts is an inability to insert and remove the device. This might be related to the fact that OC devices are smaller than other conventional products. Results would suggest that dispensing professionals need to spend more time training the OC user on proper insertion and removal techniques.
4. The domed tip and thin tube need to be changed more often than the traditional plumbing found on non-OC products.
5. Given the narrow diameter of the thin tubing used with OC products, insufficient high-frequency gain may be a widespread problem, especially when the majority of professionals rely on first fit algorithms without probe microphone verification.
Based on the fact that OC devices enjoy widespread popularity and very high satisfaction ratings from professionals, it is important to investigate carefully some of the potential problems associated with OC devices that may contribute to lower than expected patient satisfaction. There have been several reports that shed light on some of the potential limitations associated with OC device use.
These findings drive home the point that no single model or style is the all encompassing answer when it comes to Hearing Instrument selection. Although OC popularity continues to rise, it is the responsibility of the professional to customize the style and model to best meet the needs of each patient in everyday listening situations. While OC devices offer many advantages, many of which have been substantiated with real-world evidence, they do have limitations.