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ORIGINAL ARTICLE
Year : 2017  |  Volume : 4  |  Issue : 1  |  Page : 19-25

Comparison of two hearing aid fitting formulae in improving the patients’ satisfaction with amplification for experienced hearing aid users


1 Audiology & Vestibular Disorders Department, Faculty of Medicine, Cairo University, Cairo, Egypt
2 Audiology Unit, Hearing and Speech Institute, Cairo, Egypt
3 E.N.T. Department, Audiology Unit, Cairo University, Cairo, Egypt

Date of Submission30-Apr-2017
Date of Acceptance05-Jun-2017
Date of Web Publication31-Aug-2017

Correspondence Address:
Mai M El-Gohary
Audiology Unit, Hearing and Speech Institute, 22 El Baron City, Kattameya, Maadi Ring Road, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aaaj.aaaj_5_17

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  Abstract 

Introduction
The effectiveness of real word satisfaction is very important for optimal hearing aid (HA) fitting, which can be assessed using self-report questionnaires. The Client Oriented Scale of Improvement (COSI) and Abbreviated Profile of Hearing Aid Benefit (APHAB) are useful tools for assessing the effectiveness of HA in achieving patient satisfaction.
Patients and methods
This study included 20 hearing-impaired adults. Their hearing thresholds ranged from moderate to moderately severe sensorineural hearing loss and had previous experience with HAs. Their ages ranged from 18 to 60 years, and the mean duration of HA experience was 3.85±5.02 years. Participants were examined in three scheduled sessions: unaided, aided National Acoustics Laboratories-Nonlinear 2 (NAL-NL2), and aided desired sensation level (DSL) v5. Each session was scheduled 2 months after the previous session. Patient satisfaction was assessed using the COSI and APHAB questionnaires for each HA fitting formulae.
Results
Both formulae have improved patient’s five client needs of the COSI; however, NAL-NL2 had better final ability score compared with DSL v5. Using the APHAB questionnaire, both formulae have decreased the listening difficulty score significantly. Using APHAB questionnaire, NAL-NL2 showed significantly less listening difficulty compared with DSL v5 as regards difficulties in ease of communication, broadband noise, and reverberation. However, both formulae did not improve ‘aversiveness’ conditions.
Conclusion
Questionnaires are equally important to audiometric tests and should not be underestimated and hence should be relied upon it in HA-fitting verification.

Keywords: Abbreviated Profile of Hearing Aid Benefit, Client Oriented Scale of Improvement, desired sensation level v5, hearing aids, National Acoustics Laboratories-Nonlinear 2, questionnaires


How to cite this article:
Shabana M, Selim MH, Abd El-Latif SM, Hamdy MM, El-Gohary MM. Comparison of two hearing aid fitting formulae in improving the patients’ satisfaction with amplification for experienced hearing aid users. Adv Arab Acad Audio-Vestibul J 2017;4:19-25

How to cite this URL:
Shabana M, Selim MH, Abd El-Latif SM, Hamdy MM, El-Gohary MM. Comparison of two hearing aid fitting formulae in improving the patients’ satisfaction with amplification for experienced hearing aid users. Adv Arab Acad Audio-Vestibul J [serial online] 2017 [cited 2017 Oct 21];4:19-25. Available from: http://www.aaj.eg.net/text.asp?2017/4/1/19/213893


  Introduction Top


Hearing aid (HA)-fitting procedures usually focus on the evaluation of the prescribed gain and whether or not it matches the target, but it does not evaluate whether the patient will benefit from such prescribed HA gain. A patient can have significant benefit as measured using audiological tests but report dissatisfaction as reported by self-report questionnaires [1].

Recently revised independent fitting procedures, National Acoustics Laboratories-Nonlinear 2 (NAL-NL2) [2] and desired sensation level multistage input/output [DSL m(i/o)] [3], both increase sound audibility and speech intelligibility [4]. NAL-NL2 maximizes speech intelligibility and equalizes the loudness to that perceived by normal hearer. DSL m(i/o) normalizes the loudness across a wide range of input level based on the hearing thresholds [5]. Both formulae aim to increase real life satisfaction; however, there is scarcity of literature, which compares its effectiveness using self-report questionnaires.

The effectiveness of real word satisfaction is very important for optimal HA fitting, which can be assessed using self-report questionnaires [6]; the Client Oriented Scale of Improvement (COSI) and Abbreviated Profile of Hearing Aid Benefit (APHAB) are useful tools for assessing the effectiveness of HA in achieving patient satisfaction [7].

COSI is a scale in which the patient nominates five listening situations that need to be improved after amplification. After HA fitting the patient rates the degree of change and the final ability in a five-point scale. This makes COSI flexible and easy to be applied in clinical work as it is not comprise fixed predetermined questions that does not account for patient communication preference [8]. The APHAB questionnaire is more concerned with the disabilities of the patient than with the emotional factors. It is composed of 24 items divided into four subscales; ease of communication (EC) (communication in easy listening situations); broadband noise (BN) (speech understanding in noisy condition); reverberation (RV) (speech understanding in reverberant situation); aversiveness (AV) (the reaction to environmental unexpected sounds such as alarm bell). The patient completed the APHAB in unaided and aided condition and the benefit was calculated to be the difference between the two [9].

We aimed to compare the effectiveness of the recently revised NAL-NL2 and DSL m(i/o) formulae to improve the subjective satisfaction of patients with previous experience of wearing the HAs.


  Patients and methods Top


This research was conducted and designed by the cooperation of the Audiology Unit of Cairo University and the Audiology Unit of Hearing and Speech Institute. The study examined 20 adults’ patients suffering from moderate to moderately severe sensorineural hearing loss (flat or gradually falling configuration) who had previous HA experience. There were six male and 14 female patients. Their ages ranged from 18 to 60 years.

Exclusion criteria

  1. Conductive and mixed hearing losses.
  2. Retrocochlear pathologies.
  3. HA first users.
  4. Normal, mild, and profound hearing losses.


Each patient had three test sessions. Session one included history taking, basic audiological evaluation, the programming of the HA with one of the two formulae applied in this research, answering the unaided APHAB to assess the unaided difficulties, and choosing the five first priority needs of COSI questionnaire. Session two was scheduled at 2 months following session one and included HA reprogramming according to the second formula and answering COSI and APHAB based on the first formula. Session three was scheduled after 2 months of session two. It included answering the COSI and APHAB questionnaires for the second formula. The choice of the first formula was chosen randomly: 10 patients were fitted first with NAL-NL2 and 10 patients were fitted first with DSL m(i/o).

All patients were subjected to the following tests: history taking including age, sex, residence, occupation and specific special habits, audiological symptoms such as hearing loss, tinnitus, discharge, otalgia, and vertigo; full history of hearing loss, including onset, course, duration, expected cause, and history of HAs used; and physical and otological examination.

Basic audiological evaluation

The basic audiological tests were carried out for all patients to confirm the presence of moderate to moderately severe sensorineural hearing loss with flat or gradually falling configuration (flat is <5 dB rise or fall per octave, whereas gradually falling is 5–12 dB increase per octave [10]). Behavioral audiometry was carried out in a double-walled, sound-attenuated room using calibrated audiometers Interacoustic AC40 (Middlefart, Denmark). Air conduction pure-tone thresholds at frequency ranges from 250 to 8000 Hz and bone conduction thresholds at frequency ranges from 500 to 4000 Hz were assessed using Acoustic Immittancemeter: Interacoustics A/S AZ26 (Middlefart, Denmark), with a probe tone 226 Hz. The tympanograms were classified according to Jerger’s classification (A, As, Ad, B, and C) tympanogram [11].

Aided thresholds were presented through AC40 interacoustic loudspeaker placed at an azimuth of 0° and a distance of 1 m from the tip of the participant’s nose. Thresholds were assessed using a 10-down/5-up dB paradigm following clinical convention/standards of 500, 1000, 2000, and 4000 Hz warble signals.

Hearing aid programming

A desktop personal computer interfaced with HI-PRO system was used for programming the HA [Behind The Ear (BTE) digital HA Bernafon Inizia-3-system; Bernafon, Bern, Switzerland]. Monaural fitting was chosen due to financial reasons. The HA was programmed using the Bernafon manufacturer’s HA fitting software: OASIS version 21 according to NAL-NL2 and DSL m(i/o) formulae. HA gain, release time, and compression ratio were systematically adjusted using the programming software. Noise reduction was turned on.

Questionnaires

The questionnaires (Arabic versions) were administered after using each fitting procedure for 2 months to assess its benefits. The scores were compared and examined to assess the changes in performance after each fitting. COSI questionnaire was developed by the NAL Arabic Translation of the COSI [12]. The COSI is an open-ended scale in which the patient chooses up to five listening situations from a list of 16 situations in which he or she experienced communication difficulties that affect his daily life activities. The situations are ordered according to its importance to the patient, and then the patient chose the degree of change, which estimates HA benefit and the final ability, which estimates hearing instrument performance at this specific need. In both measures a higher number means better improvement.

APHAB form ‘A’ was used with the original Cox scoring [9]. The goal of the APHAB is to quantify the disability caused by hearing loss, and the reduction in that disability achieved with HAs. The APHAB uses 24 items covering four subscales referring to speech recognition in daily environments: EC includes six items describing the effort involved in communication under relatively easy listening conditions; BN includes six items describing speech understanding in the presence of multitalker babble or other environmental competing noise; RV includes six items describing speech understanding in moderately reverberant rooms; and AV of sounds includes six items describing negative reactions to environmental sounds. The results of each subscale were given as percentages of difficulty with listening in that specific situation after 2 months’ experience with the HA. The participants completed the APHAB at both aided and unaided conditions by indicating what percentage of time they experience difficulty in each situation described in the inventory. A person’s score on each subscale is the mean rating of the six items making up the subscale. A global score is the mean of the scores for all items in the EC, RV, and BN subscales, which assess the increase in speech understanding in various everyday environments. The benefit was calculated by subtracting the aided average from the unaided average.

Statistical analysis of the collected data

Results were collected, tabulated, and statistically analyzed using an IBM compatible personal computer with SPSS (version 20, Released 2011, IBM SPSS Statistics for Windows; IBM Corp., Armonk, New York, USA). Student’s t-test is a test of significance used for comparison of quantitative variables between two groups of normally distributed data, whereas Mann–Whitney’s U-test was used for comparison of quantitative variables between two groups of not normally distributed data. The analysis of variance test was used for comparison of quantitative variables between more than two groups of normally distributed data with LSD test as post-hoc test, whereas the Kruskal–Wallis test was used for comparison of quantitative variables between more than two groups of not normally distributed data with Tamhane’s test as post-hoc test. A P of less than 0.05 was considered significant.


  Results Top


This study included 20 hearing-impaired adults who previously used the HA. Their mean age was 38±16 and their ages ranged from 18 to 60 years and the duration of HA experience was 3.85±5.02. The sex distribution was as follows: six (30%) male and 14 (70%) female. They had moderate to moderately severe hearing loss.

Aided thresholds

[Table 1] demonstrates that there were no statistically significant differences between the two formulae.
Table 1: Comparison between the aided thresholds of National Acoustics Laboratories-Nonlinear 2 and desired sensation level v5 formulae at the different frequencies

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Client oriented scale of improvement

The priority needs for all patients (from 1 to 6) are the following ([Figure 1]): conversation with one or two in quiet; conversation with a group in noise; television/radio at normal volume; increased social contact; feel embarrassed or stupid; hear traffic. The majority of patients have chosen category number ‘1’ (conversation with one or two in quiet) in COSI questionnaire as the first priority need to be improved. [Table 2] presents the comparison between NAL-NL2 and DSL m(i/o) formulae as regards the final ability with HA in improving the five client needs. NAL-NL2 formula statistically significantly improved the final ability of the patient at needs 1 and 4 compared with DSL m(i/o) formula. [Table 3] presents the comparison between the mean degrees of change in the two fitting formulae in the five reported client needs. It demonstrates that NAL-NL2 had statistically significantly better degree of change compared with DSL m(i/o) at need 1 and 4. [Figure 2] shows the distribution of the degree of change in the five reported needs of COSI questionnaire. Using NAL-NL2 formula, ‘much better’ was the most frequently chosen degree of change [42 (42%) times out of 100 times], whereas ‘better’ was the most frequently chosen in DSL m(i/o) [38 (38%) times out of 100 times].
Figure 1: First priority need from the 16 different categories in Client Oriented Scale of Improvement

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Table 2: Comparison between the final ability score (%) of Client Oriented Scale of Improvement questionnaire in improving the five client needsa using National Acoustics Laboratories-Nonlinear 2 and desired sensation level multistage input/output formulae

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Table 3: Comparison between National Acoustics Laboratories-Nonlinear 2 and desired sensation level multistage input/output formulae ‘degree of change’ in improving the five client needsa of Client Oriented Scale of Improvement

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Figure 2: The distribution of degree of change in the five reported needs of Client Oriented Scale of Improvement questionnaire

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Abbreviated profile of hearing aid benefit

[Table 4] presents the comparison between the mean and SD of global APHAB and APHAB subscales as regards the listening difficulties without HA, with HA using NAL-NL2 formula, and with HA using DSL m(i/o) formula, as follows: EC, as a listening difficulty, was highly statistically significantly improved in aided condition using NAL-NL2 and DSL m(i/o) than without HA use. EC was statistically significantly better in NAL-NL2 than in DSL m(i/o). BN, as a listening difficulty, was highly statistically significantly improved using NAL-NL2 formula and statistically significantly improved using DSL m(i/o) formula than without HA. BN was highly statistically significantly better in NAL-NL2 than DSL m(i/o). RV, as a listening difficulty, was highly statistically significant improved in aided condition using NAL-NL2 and DSL m(i/o) than without HA use. RV was highly statistically significantly better in NAL-NL2 than in DSL m(i/o). AV, as a listening difficulty, showed no statistically significant difference neither between the two HA fitting formulae nor between the formulae and without HA. Global APHAB score for listening difficulties was highly statistically significantly lower for NAL-NL2 and DSL m(i/o) than without HA (P1 and P2 values), and NAL-NL2 has highly statistically significantly lower global score compared with DSL m(i/o) (P3 value) ([Table 4]). [Table 5] presents the comparison between mean and SD of HA benefit, scored using APHAB subscales using NAL-NL2 and DSL m(i/o) formulae. NAL-NL2 formula has a highly statistically significantly better HA benefit score for EC and BN compared with DSL m(i/o), whereas there were no statistically significantly difference between the two formulae as regards RV and AV.
Table 4: Comparison between global Abbreviated Profile of Hearing Aid Benefit and Abbreviated Profile of Hearing Aid Benefit subscales, without the hearing aid, using National Acoustics Laboratories-Nonlinear 2 and desired sensation level multistage input/output formulae

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Table 5: Comparison between hearing aid benefit scored by Abbreviated Profile of Hearing Aid Benefit subscales using National Acoustics Laboratories-Nonlinear 2 and desired sensation level multistage input/output formulae

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  Discussion Top


Client Oriented Scale of Improvement

The COSI is a useful tool for assessing listening needs and the effectiveness of HA fittings in meeting these needs, as reported by the patients [6]. The current study has demonstrated improved subjective satisfaction with HA across different listening situations. The majority of patients have chosen category number ‘1’ (conversation with one or two in quiet) in COSI questionnaire as the first priority need to be improved. This is in agreement with the results of Scollie et al. [3]. They studied patients with bilateral moderate to moderately severe sensorineural hearing loss including 24 children and 24 experienced adults and 24 new HA adult users. Prescriptive targets were calculated according to DSL i/o algorithm. The COSI questionnaire used to evaluate HA performance indicated that the largest mean COSI scores were in situations of listening in quiet, listening to the television or radio, and in conversation in a group with noise in the background. Similarly, the average degree of change was 4.1, corresponding to a rating of ‘better’. Similarly, in the current study ‘better’ was the most frequently chosen degree of change using DSL m(i/o) formula.

Emerson and Job [13] studied 111 adults with moderately severe to severe sensorineural hearing loss; COSI questionnaire was given before HA fitting, 2 weeks after HA fitting and 6 months later. They reported that ‘conversation with one or two in quiet’ is the first priority need and ‘better’ was the most frequent degree of change frequently reported by the patients.

In contrast, Dillon et al. [14], Polonenko et al. [6], and Shabana et al. [7] reported ‘conversation with a group in noise’ to be the first priority need. However, listening in quite was from the five client needs. Conversation with a group in noise was the second priority need in our study. This could be attributed to the fact that the majority of our patients were housewives, usually spending much time with their families, so they were more concerned with listening in quite than in noise.

Both formulae improved the patient’s five client needs. However, NAL-NL2 had better final ability score compared with DSL m(i/o) in all client needs, reaching statistical significance in need 1 and need 4 ([Table 2] and [Table 3]).

Using NAL-NL2 formula, ‘much better’ was the most frequently chosen degree of change [42 (42.0%) times out of 100 times], whereas ‘better’ was the most frequently chosen in DSL m(i/o) [38 (38.0%) times out of 100 times]. This is in agreement with Shabana et al. [7], who studied 19 adults with moderately severe sensorineural hearing loss, fitted with nonlinear HA; three HA fitting formulae were applied and compared as regards the functional performance of real life situations. They reported better or much better in 84.2% with NAL and 36.9% with DSL. NAL provided better results compared with DSL.

Abbreviated Profile of Hearing Aid Benefit

Using APHAB questionnaire, NAL-NL2 showed less listening difficulty in different real-life listening situations compared with DSL m(i/o). Both formulae have decreased the listening difficulty score significantly; however, NAL-NL2 score was statistically significantly lower/better than DSL m(i/o) in difficulties in EC, BN, and RV. However, both formulae had similar results as regards AV, which represents the patient reaction to loud environmental sounds and both formulae did not improve this condition compared with unaided situations. Moreover, AV dissatisfaction increased using both formulae, although not reaching statistical significance level ([Table 4]). This is in agreement with Shabana et al. [7], who reported similar results, however, that the AV was mostly perceived using DSL than using NAL.

Amorim and Almeida [15] studied 16 patients with bilateral symmetric moderate-to-severe sensorineural hearing loss, fitted with NAL-NL1. At the initial period of HAs adaptation, after 4 weeks and 16/18 weeks of amplification, they reported that the majority of patients presented a statistically significant increase in the benefit with HAs using APHAB. However, they observed that AV increased, suggesting an increase in acoustical signal audibility after amplification.

In the current study, APHAB benefit scores showed better improvement in EC, BN, and RV in NAL-NL2 than in DSL m(i/o), which was statistically significantly better in NAL-NL2 in EC and BN only ([Table 5]). Only the AV benefit score was negative; Walden et al. [16] reported that patients with long-term hearing loss have unrealistic expectations and report increased AV to loud sounds encountered in their daily life. In addition, patients who wear HA with noise reduction also reported increased AV problems after HA fitting than when they were unaided [17],[18]. Both new and previous HA users should be counseled to understand increased audibility after HA fitting [19].

Patients reported in both questionnaires more satisfaction with NAL-NL2 than with DSL m(i/o). This could be attributed to the fact that patients were experienced HA users. It is fairly well documented that nonexperienced HA users prefer less amplification compared with experienced HA users [20]. Currently, DSL m(i/o) does not incorporate a correction for gain, based on new or experienced HA user status [3]. NAL-NL2 incorporates adjustments of gain adaptation for adult new HA users with more than mild hearing impairment [2].

Aided thresholds

Unlike questionnaires, the aided sound field thresholds showed no statistically significant differences between the two formulae. This is in agreement with Johnson and Dillon [4], who examined the impact of both formulae on seven hypothetical hearing loss configurations. They concluded that both formulae have comparable overall loudness, comparable speech intelligibility in quiet and in noise and the insertion gain differences were small for flat sensorineural hearing loss, ±5 dB.

Cox and Alexander [9] reported that the objective methods measuring HA benefit might not be correlated with patient’ self-reported benefit in adverse listening situations and the lack of correlation in adverse situation could be due to the presence of other factors that determine patient’s satisfaction such as central auditory processing of speech and cognitive ability. In addition, different factors encountered in ‘real life’ situations may not be present in ‘well formulated’ testing condition. We conclude that questionnaires are equally important to audiometric tests and should not be underestimated and hence should be relied upon it in HA fitting verification.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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