A step-by-step how-to guide to real-ear verification—and optimizing its benefits
Real-ear verification of hearing aid gain and features has a long history of being a hot topic in the literature—and remains so today. Numerous studies have pointed to the rationales for performing verification measures in terms of providing the highest level of service to the patient and the patient’s significant others.
Verification measures provide objective evidence of the appropriateness of the fitting by ensuring that target gains are met and output levels are adequately high, yet do not exceed the patient’s uncomfortable levels. They can also ensure proper functionality of the hearing aid, including features such as directionality and noise reduction, which can prevent unnecessary and time-consuming repairs and returns.
In addition, verification instills confidence in the patient about the quality of the hearing services received, and may promote greater satisfaction among both patients and clinicians alike.1-4
Overcoming Obstacles: Basic Verification in a Changing Field
Along with the reasons for verifying the hearing aid, there are innumerable studies showing the expected outcomes in the verification process of gain and features. These papers typically show screen prints of real-ear equipment results for “good”—and sometimes “poor”—fittings. While this literature is valuable for exhibiting what to expect after the measurements are obtained, often the steps taken to achieve these results are summarized only briefly. The middle step between the desirability and the outcome of proper verification measures is often omitted. Without this step, it may be difficult to know exactly how to verify an aspect of hearing aid performance.
Additional variables in hearing aid verification include the ever-changing aspects of hearing aid features as they are developed to higher and higher levels nearly constantly among manufacturers. Even if a clinician typically chooses to fit hearing aids from a few select manufacturers, understanding new features and how the settings affect the overall fitting can be challenging. Learning how these new features function, especially in terms of the expected performance while obtaining real-ear measurements, can be time-consuming.
Another variable that can alter verification procedures involves the equipment used in the process. For example, the Audioscan Verifit system underwent a software update in the past few years that introduced changes including the Viewport option.5 Likewise, GN Otometrics recently released a module-based verification system called the new Aurical, which includes a FreeFit system for probe-microphone measures.6 Changes in the verification equipment introduce new protocols and procedures for verifying aspects of the hearing aid.
Overcoming these variables entails taking time to understand the hearing aid features and learning about the changes in the equipment. It is beyond the scope of this article to detail the specific updates in hearing aid features today, or to provide specific steps for all the available verification systems. However, this article will outline general protocols for verifying gain and output, plus two typical hearing aid features: directionality and noise reduction. We will focus on probe-microphone measurements, and include “recipes” for verifying hearing aid audibility and these features.
As with any recipe, there may be variations that are also acceptable. This article in no way provides all possible ways of verifying each feature. Further, every case and patient is different, so accommodations must be made when using these “recipes” for clinical verification. Thus, this article only provides basic generic recipes for verification success with hearing aid features; further adjustments and “tweaks” may be necessary depending on the patient, the equipment used, and the “chef” (the hearing professional).
Preparing the Mise en Place
Professional chefs usually organize their kitchen equipment and ingredients for a recipe as a first step to ensure culinary success. This includes reviewing the recipe, measuring out ingredients, and ensuring that the necessary tools are functional and nearby before beginning to cook. This process, usually referred to as mise en place (French for “putting in place”), prevents oversights, such as a missing ingredient or a dysfunctional piece of equipment, from ruining or otherwise derailing preparation of the recipe.
In much the same way, getting ready to verify hearing aid gains and features with a patient requires preparing the mise en place, as well (Table 1). First, it is important to review how the real-ear equipment works, and have a rudimentary understanding of the features you’d like to verify. Then it is helpful to assemble and pre-measure the length of the probe-tube to be inserted in the patient’s ear. Finally, you should ensure that a chair for the patient, an otoscope, and any other materials you need for storing the real-ear measurement results (eg, a jump drive) are near the equipment. You also want to ensure that you have a PC and some other programming equipment in reasonable proximity to the real-ear equipment while the hearing aids are connected either wirelessly or via wires.
The recipes included here were written generally based on two commercially available real-ear systems today, the Audioscan Verifit and the Otometrics Aurical FreeFit. The Audioscan Verifit (Model VF-1) is a system that analyzes hearing aid performance, either when affixed to a standard coupler in the test box or while worn in the patient’s ear. It contains a Viewport option that streamlines the process of verifying audibility, directionality, noise reduction, and feedback. The Otometrics new Aurical is a modular system that assists in many aspects of hearing aid fitting. It includes a fitting audiometer, a loudspeaker, the wireless FreeFit Probe Microphone Measurements (PMM) unit, and a test box (coupler unit). It can be used as a complete system or as separate components. The FreeFit module is a collar that includes two probe microphone assemblies, allowing for wireless binaural measurements.
When using either real-ear system, verification of the fitting helps to demonstrate the benefits of hearing aid amplification to the patient and the patient’s significant other. Besides gain and output verification, both the Audioscan and the Otometrics equipment include convincing tools that illustrate the benefits of specific hearing aid features such as noise reduction and directionality. The Verifit on-ear system contains Speechmap, Insertion Gain, Directional, Feedback, Noise Reduction, Occlusion, and real-ear to coupler difference (RECD) tests. The Aurical PMM module consists of Dynamic REM, Speech Mapping, a customizable Freestyle test that may be used for demonstrating a wide range of hearing aid features, and FitAssist tools, such as the Feedback Finder and the Occluded Probe-Tube Detector.
It should be recognized that other REM/fitting systems are available, and most of the recipes below would also apply to them and their features. To prepare the mise en place for most verification equipment, even before the patient arrives, a recipe for equipment readiness as shown in Table 1 can be followed.
Recipes for Verification
Recipes for verifying hearing aid gains and maximum outputs, and how to verify directionality and noise reduction, (click here for recipes in pdf format). The gain and output measure ensures that the hearing aid is properly programmed for the patient’s hearing loss. The core principles for ensuring proper hearing aid gain and output are that soft and conversational sounds are audible to the patient, and that loud sounds are not too loud.
Verification of directionality and noise reduction provides evidence that the features are working, and gives information about the amount of reduction of background noise provided by each feature. Fine-tuning of the hearing aids can occur in concert with verification procedures when the devices are connected to the fitting software. In some recipes, figures are available, which were obtained through the new Aurical FreeFit system.
Variation: You may also test noise reduction with the same test used to verify gain and output. Select a noise-like stimulus at an average or loud level and observe over about 20 seconds how the hearing aid reduces the level of the noise. Capture the curve and save/print it for a record to insert in the patient’s file.
The Pièce de Résistance: Sharing the Results with the Patient
The pièce de résistance refers to the best aspect of something, which makes the entire collective experience extraordinary, distinctive, or significant. When verifying hearing aid gains or features, the pièce de résistance is communicating the results of your tests to the patient. This highlights to them the professional nature of your services and the value of their purchase—and assures them that their hearing aid not only is functional but also can be beneficial for their specific hearing needs.
Audibility and comfort. When communicating the gain and output verification results, start by explaining the display screen. The display includes hearing thresholds and measured/estimated levels of discomfort to the patient. The display also includes the area where speech sounds occur across the frequency range for typical conversation input levels. Frequently, the fitting target curves for the patient’s hearing loss are also displayed.
Explain that the probe-tube, which is placed in the ear canal, measures the amplified signal at the eardrum level with the hearing aid in place. Different input levels are used to demonstrate the amplification for soft sounds and loud sounds, and, when compared to the hearing thresholds, also provide a direct indication of the audibility of sounds to the patient. The test with a loud input level ensures that loud sounds in the real world will not exceed the patient’s measured levels of discomfort.
Directionality. The directional test can be used to describe to the patient how the feature works. Explain that sounds from the back are reduced while sounds from the front are maintained. Since people usually attempt to face the person speaking, directionality can make it easier to discriminate sounds in background noise.
Noise reduction. To communicate the results of noise reduction verification, inform the patient that you are testing the ability of the hearing aid to reduce noise and thereby make listening in noisy situations more comfortable. If you have set the noise reduction feature to a “Strong” setting to best show the feature’s capabilities, inform your patient of this change, and whether it will be a temporary setting or one that will be used by the patient after the fitting.
Explain that the first curve shows the response of the signal immediately before the noise reduction takes effect or with noise reduction “off,” and that the second curve shows the reduced response when noise reduction is activated. The difference between the two curves is the amount of noise reduction the hearing aid provides.
Real-ear verification is generally considered a “best practice” when fitting and fine-tuning hearing aids. Knowing the basic procedures in verifying the hearing aid is, at least, half the battle. Yet it is also important to communicate the results to the patient, to assure confidence in the professional services provided, as well as the effectiveness of the patient’s hearing aids. Both of these factors can have a large impact in the success of the fitting as a whole, and can help promote a higher degree of satisfaction.
Degustation is a word used in the culinary world to mean an “appreciative sampling of different foods.” Verifying hearing aid gains, outputs, and features also gives the hearing care professional and the patient a good idea of the spread of functionality afforded by the technology. By illustrating hearing aid outputs and features on the real-ear equipment display screen while different sounds are presented, the patient is treated to a more meaningful and sensory fitting experience.
Correspondence can be addressed to HR or Tammara Stender, AuD, at .
- Strom KE. HR interviews Sergei Kochkin, PhD. Hearing Review. 2005;12(11):24-32,82. Available at: www.hearingreview.com/issues/articles/2005-10_03.asp. Accessed January 18, 2012.
- Valente M, Potts LG, Valente M. Signal testing approaches: clinical procedures to improve user satisfaction with hearing aids. In: Tobin H, ed. Practical Hearing Aid Selection and Fitting. Baltimore, Md: Department of Veterans Affairs; 1995:Chapter 6.
- Stender T, Appleby R, Hallenbeck S. V&V and its impact on user satisfaction. Hearing Review. 2011;18(4):12-21. Available at: www.hearingreview.com/issues/articles/2011-04_01.asp. Accessed January 18, 2012.
- Kochkin S, Beck DL, Christensen LA, et al. MarkeTrak VIII: The impact of the hearing healthcare professional on hearing aid user success. Hearing Review. 2010;17(4):12-34. Available at: www.hearingreview.com/issues/articles/2010-04_01.asp. Accessed January 18, 2012.
- Audioscan. Verifit Online User Manual. Dorchester, Ontario: Audioscan. Available at: www.audioscan.com. Accessed January 18, 2012.
- GN Otometrics. Aurical FreeFit Quick Start, Fitting Systems and Online User Manual. Available at: www.otometrics.com. Accessed January 18, 2012.
- Bagatto MP. Optimizing your RECD measurements. Hear Jour. 2001;54(9):32,34-36.
- Holube I, Fredelake S, Vlaming M, Kollmeier B. Development and analysis of an International Speech Test Signal (ISTS). Int J Audiol. 2010;49(12):891-903.