The purpose of this paper is to demonstrate evidence-based best practice for hearing aid fitting procedure. Literature review has been completed, and when evidence based studies were not found, manufacturers’ white papers were reviewed. This patient is a 75 year old man who has a bilateral symmetrical mild to moderately severe sensorineural hearing loss above 500 Hz with good word recognition scores in each ear. The patient expressed difficulty talking to his wife in the car and from distance at home.
He reported they do not go out often, but when they do, it is typically just a group of three or four people. He is retired and works with his wife in her own business at home, making handmade wooden crafts. He is not concerned about cosmetics and prefers a hearing aid that sits behind his ear like the ones his neighbor has. Given the degree and configuration of his hearing loss, I would recommend a receiver in the canal hearing aid with an open dome, particularly Starkey Muse Micro RIC-312 with a 50-gain receiver. Why this hearing aid is a good fit for this patient will discussed in the paper.
Consultation and Selection Before determining the patient’s candidacy for hearing aid fitting, a complete audiological assessment should be conducted (American Speech-Language and Hearing Association [ASHA], 2006). This process starts by otoscopic examination of the external auditory canal to rule out cerumen impaction that may affect the hearing test results and the fitting process and to rule out any abnormality in the shape and size of the external auditory canal (Iwahashi, de Souza Jardim, Sizenando, & Bento, 2011).
Air and bone conduction thresholds, speech recognition testing, and immittance testing must be obtained to determine the type and degree of the hearing loss prior to choosing the style and technology of the hearing aids (Iwahashi et al. , 2011). Another important part that can help in the fitting process is to measure the patient’s uncomfortable loudness levels. According to Mueller and Bentler (2005), several studies and hearing aid protocols, such as the Independent Hearing Aid Fitting Forum Protocol (Cox, 1995), have recommended measuring individual uncomfortable loudness thresholds as part of the hearing aid assessment.
These levels help in determining the maximum output levels of the hearing aid (Iwahashi et al. , 2011; Mueller & Bentler, 2005). Information about the patient’s history of recurrent middle ear infections is also important and could affect the choice of the hearing aid style (Iwahashi et al. , 2011). After gathering this information, the audiologist should make appropriate referral for medical management as needed, and a medical clearance for hearing aid use should be obtained as recommended by the Food and Drug Administration (FDA, 2015).
The cumulative test results, recommendations, and treatment plan should be discussed with the patient and guide the audiologist in the selection process (ASHA, 2006; Iwahashi et al. , 2011). It is essential to start the fitting process as soon as the hearing loss is confirmed and the medical clearance is obtained (Iwahashi et al. , 2011). The patient’s readiness and acceptance of the hearing aids should be examined. It is also important to have sufficient information about the different environments the patient is exposed to on a daily basis (Iwahashi et al. , 2011).
Furthermore, it is important to know which situations the patients feel are most affected by their hearing loss (Iwahashi et al. , 2011). There are several assessments and questionnaires that help the audiologist explore and know the patients’ communication needs in order to provide them with specific goals and realistic expectations. The patient will complete the Client Oriented Scale of Improvement (COSI; Dillon, James, & Ginis, 1997). The areas that examined by the COSI are the ones the patient is having the most difficulty with and wants to improve with the amplification (Dillon et al. 997).
The patients state up to five specific goals and situations that they feel they are most limited by their hearing loss and prioritize them (Dillon et al. , 1997). The COSI should be completed by the patient before the hearing aid fitting as recommended by Dillon et al. (1997); it provides the audiologist with good information, it takes a short time, and has good test-retest reliability (Dillon et al. , 1997). Another reliable measure that can be used with hearing aid candidates is the Hearing Handicap Inventory for the Elderly (HHIE; Ventry & Weinstein, 1982).
The HHIE measures how the patients perceive their hearing handicap (Ventry & Weinstein, 1982). These measures also aid in determining the technology level and features necessary for the patient’s communication in daily living activities. In addition to the audiological assessment information, the audiologist can incorporate the patient’s communication limitation and goals in the selection of the hearing aid and hearing assistive technology (Dillon et al. , 1997). In addition to the patient’s communication needs, the patient’s non-auditory needs play a role in the process of selecting and fitting the hearing aids.
The patients’ cognitive ability, expectation from the hearing aids by the patients and their significant other, and motivation should be explored. The non-auditory factors do not predict the success of the hearing aids; however, they are significantly related to the perception of the patient’s disability due to the hearing loss (Gatehouse,1991). Having information about the patient’s vision and motor ability help in the selection process to ensure their ability to insert and remove the hearing aids and change the battery (Erber, 2003; Iwahashi et al. , 2011).
If the patients have poor motor skills or visual problem, then they would need a support system to help them with the use and care of their hearing aids (Erber, 2003). Additionally, changes and modification to the hearing aid design may be conducted to accommodate for the patient’s impairments (Erber, 2003). After obtaining all the needed information about the patient’s audiological assessment and communication needs, the hearing aid style, technical features, and hearing assistive technology can be selected appropriately for the patient’s individual goals.
I selected a receiver in the canal hearing aid for each ear with an open fit and a 50-gain receiver. RIC hearing aids are suitable for patients with a mild to mediate sloping hearing loss (Galster, Yanz, & Freeman, 2008). Additionally, Kuk and Baekgaard (2008) recommended an open fit RIC for patients with hearing threshold better that 20 to 30 dB HL at 500 Hz and better than 50 to 60 dB HL at 1000 Hz, these thresholds and recommendations are consistent with the current patient and the selected hearing aid style.
Binaural hearing aid fitting was recommended to this patient to help in localization and speech understanding. Kalluri (2014) explained that with Starkey’s auditory scene analysis feature, spatial location cues are used to help in localization with binaural hearing. Because the patient has a quiet lifestyle, his only complaint is the inability to understand his wife’s speech in the car and from distance; I recommended the standard level with 16 channels. He would still have the features but not as powerful and advanced as the high level technology.
This hearing aid has a telecoil option, and the receiver’s fitting range is considered good for this patient’s hearing loss. This decision is based on the information from the patient and his spouse about his difficulties and communication needs. Kuk and Baekgaard (2008) recommended having signal processing features, such as noise cancellation, directional microphones, and feedback cancellation, when fitting a patient with open-fit hearing aids to lessen the disadvantage that comes from the direct sounds the patient receives from the open-fit.
The occlusion effect is a common issue among patients with normal hearing in the low frequencies or have a mild hearing loss and it is defined by Dillon (2012) as the enhancement of sound pressure level in the external auditory canal at the low frequencies when the ear is occluded with the hearing aid. This occlusion effect can be resolved by fitting the patient with an open dome (Winkler, Latzel, & Holube, 2016).
I selected an open dome for this patient based on the recommendation of Kuk and Keenan (2006) of using an open-fit hearing aid for patients with a 20 dB HL or better hearing threshold at the low frequencies. Careful consideration should be taken for low frequency gain provided by the software or fitting formula as recommended by Winkler et al. (2016). Another reason I selected this hearing aid is that the patient can benefit from the natural/direct low frequency sound quality, which may result in a possible improvement of localization (Winkler et al. , 2016).
The selected hearing aid has a directional microphone. The benefits of directional microphones are most prominent at the low and moderate loudness levels for patients with an open fit hearing aid (Bentler, Wu, & Jeon, 2006), which is due to the low frequency direct sound. While the directional benefit comes from the microphone, the direct sound does not benefit from the directional microphone or hearing processing (Bentler et al. , 2006). Keidser, Dillon, Convery, and Mejia (2013) found that the patient’s perception for directional microphones benefit was better with better directivity in the low frequencies.
Winkler et al. (2016) explained if the low frequency direct sound is louder than the high frequency amplified sound, then the patient would not benefit from the technical features of the sound processing. I selected a hearing aid with a good feedback cancellation feature based on the recommendation from Chalupper and Kasanmascheff (2008) and Lantz, Dyrlund Jensen, Haastrup, and Ostergaard Olsen (2007). They suggested that having digital feedback cancellation is important to ensure that the hearing aid is providing appropriate gain for the patient’s hearing
