Title Hearing Aid Satisfaction

Hearing aid satisfaction is a pleasurable emotional experience as an outcome of evaluation of performance. Many tools have been designed to measure the degree of satisfaction overall, or along the dimensions of cost, appearance, acoustic benefit, comfort, and service. Various studies have used these tools to examine the relationships between satisfaction and other factors. Findings are not always consistent across studies, but in general, hearing aid satisfaction has been found to be related to experience, expectation, personality and attitude, usage, experience, type of hearing aids, sound quality, listening situations, and problems in hearing aid use. Inconsistent findings across studies and difficulties in evaluating the underlying relationships are probably caused by problems with the tools (e.g., lack of validity) and the methods used to evaluate relationships (e.g., correlation analysis evaluate association and not causal effect). Whether satisfaction changes over time and how service satisfaction contributes to device satisfaction are unclear. It is hoped that this review will help readers understand current satisfaction measures, how various factors affect satisfaction, and the way satisfaction is measured and may be improved to yield more reliable and valid data. Wong, Hickson & McPherson Hearing Aid Satisfaction 3 Introduction Satisfaction, according to the Oxford Advanced Dictionary (2000), is the good feeling that one has achieved something or when something that one wanted to happen does happen. Satisfaction has been variably described in the American Heritage Dictionary of the English Language (1996) as the fulfillment or gratification of a desire, a need, or an appetite; a pleasure or contentment derived from such gratification; and a source or means of gratification. Similarly, Oliver (1997) defines satisfaction as a pleasurable fulfillment in that the consumer feels that his or her needs, desires, and goals have been fulfilled in a pleasurable manner. Satisfaction is thus an emotional and pleasurable experience, that confirms that something right has happened and provides a driving force to sustain the effort that yields this feeling. Tse (1988) defined consumer satisfaction as “the consumer’s response to the evolution of the perceived discrepancy between prior expectations and the actual performance of the product as perceived after its consumption”. Oliver (1981) further described satisfaction “as an evaluation of the surprise inherent in a product acquisition and/or consumption experience.... Satisfaction is the emotional reaction following a disconfirmation experience (an evaluation of performance against expectations) which acts on the base attitude level and is consumption-specific”. Overall, satisfaction is commonly described as a pleasurable emotional experience, as an outcome of product performance evaluation against expectations. Satisfaction is crucial to the whole hearing aid fitting process and its importance in audiology is evidenced by the fact that it is frequently included as a measure of outcome (Cox and Alexander, 1999; Dillon et al, 1999; Kochkin, 2000a). Satisfied hearing aid users are often frequent users and sources of referral for other people with hearing impairment (Kochkin, 2000a). Allen and Rao (2000) and the National Research Council (1999) also Wong, Hickson & McPherson Hearing Aid Satisfaction 4 stated that satisfaction is necessary although not sufficient for a customer to be loyal. Customer satisfaction and loyalty directly affect customer retention. Thus, it is important to investigate the nature of hearing aid satisfaction and how audiologists can achieve higher satisfaction for their clients. A number of researchers have found that most hearing aid users are satisfied with their hearing instruments (Kochkin 1990; Sinclair and Goldstein, 1991; Kochkin, 1992; Bentler et al, 1993; Humes et al, 2002a; Humes et al 2002b). For example, the two Kochkin studies reported more than 50% of users were generally satisfied with their hearing aids. Kochkin (1996a), and Billie et al (1999) have found that more than 66% of participants were satisfied or very satisfied. In the study by Scherr et al. (1983), 91% of respondents rated hearing aid performance satisfactory or excellent. Souza et al. (2000) also found high overall satisfaction among hearing aid users. Hosford-Dunn and Halpern (2000) found that the overall satisfaction rating reached 71%. The average participant in the Cox and Alexander (2001) study was “considerably satisfied”. The studies mentioned thus far have all been conducted in the United States. Hearing aid users in other countries are also quite satisfied. In three separate Australian studies, 71 to 97% of users reported feeling satisfied or very satisfied with hearing aids (Dillon et al, 1991a; Dillon et al, 1997; Hickson et al, 1999). Purdy and Jerram (1998), and Jerram and Purdy (2001) found 70 to 76% of New Zealand hearing aid users satisfied with their hearing aid experience. Similarly, over 68% of British, German and Danish users were satisfied with their hearing instruments (Gatehouse, 1994; Stock et al, 1997; Parving, 2003). These results for general satisfaction are encouraging to note, and the hope is that by studying the elements that underlay satisfaction, we can help our clients to be even more satisfied. This paper reviews 45 studies on hearing aid satisfaction under five main sections: (1) Current hearing aid satisfaction measures, Wong, Hickson & McPherson Hearing Aid Satisfaction 5 (2) Methodologies of hearing aid satisfaction studies, (3) Findings on the effect of intrinsic factors on satisfaction, (4) Findings on the impact of extrinsic factors on satisfaction, and (5) Problems with hearing aid satisfaction measures. In the first section, two commonly used hearing aid satisfaction measurement tools, will be described: the Satisfaction with Amplification in Daily Life (SADL) (Cox and Alexander, 1999) and the MarkeTrak Satisfaction Survey (or MarkeTrak). In the second section, methodologies used in studies on hearing aid satisfaction are summarized in the text and Table 4. Due to the vast number of measures used in various studies, readers are advised to refer to Table 1 for abbreviations used. In the third and forth sections, results from studies concerning how various intrinsic and extrinsic factors relate to satisfaction are discussed (see Table 5 and Table 6 for summaries). While general conclusions are drawn from studies, conflicting findings are noted. Shortcomings related to hearing aid satisfaction measures and suggestions on how these measures can be improved are covered in the last section. Current hearing aid satisfaction measures In the literature, overall hearing aid satisfaction has consistently been related to the dimensions of cost, appearance, acoustic benefit, comfort, and service (Cox and Alexander, 1999; Kochkin, 2000a). To date, only two hearing aid satisfaction measures have been somewhat “standardized”: the Satisfaction with Amplification in Daily Life (SADL; Cox and Alexander, 1999) and the MarkeTrak Satisfaction Survey (or MarkeTrak). The items in the SADL assess hearing aid satisfaction in four subscales (Table 2): 1. Positive effect items evaluate improvement in performance and psychological benefit. Cox and Alexander (2000) concluded from previous studies that this “domain appears to be the largest single contributor to variance in overall satisfaction (p. 370)”. Wong, Hickson & McPherson Hearing Aid Satisfaction 6 2. Service and cost items tap dispenser competence, cost and product dependability; 3. Negative features items relate to problems in noise, feedback and telephone use. 4. Personal image items are related to appearance. Item development, test-retest reliability, and validity measures of the SADL were evaluated by Cox and Alexander (1999, 2000), and Hosford-Dunn and Halpern (2000) confirmed its factor structure. Participants are asked to rate the hearing aid on a seven-point scale, with descriptors equal interval apart (Cox and Alexander, 1999). The descriptors are “not at all”, “a little”, “somewhat”, “medium”, “considerably”, “greatly” and “tremendously” with accompanying scores of 1 to 7. Composite scores are calculated for each of the four subscales and for the full scale (global score). Interestingly, individuals are never asked to rate satisfaction directly. Even so, Cox and Alexander (2001) found that scale and subscale scores were related to satisfaction in general. The MarkeTrak, which has surveyed the largest samples among all hearing aid satisfaction measures, has been conducted five times since 1989, and different versions are referred to as MarkeTrak I to V (Kochkin, 1990; Kochkin, 1992; Kochkin, 1996a; Kochkin, 1996b; Kochkin, 1997a; Kochkin, 1997b; Kochkin, 1998; Kochkin, 1999; Kochkin, 2000a; Kochkin and Rogin, 2000). The current MarkeTrak surveys overall hearing aid satisfaction and satisfaction in three main categories. Items in the categories are grouped on an a priori basis, as follows: 1. Product Feature items examine areas like fit or comfort, reliability, use in noisy situations and battery life. There are 20 statements. 2. Listening Situations consist of 14 statements that tap listening in small groups, restaurant, car etc. 3. The Service factor is made up of six statements (e.g., quality of service, knowledge of dispenser). Wong, Hickson & McPherson Hearing Aid Satisfaction 7 There are 40 items. A five-point Likert scale of “very satisfied”, “satisfied”, “neutral”, “dissatisfied” and “very dissatisfied” is used for response categories. Participants are asked to evaluate their level of satisfaction for each statement. Results obtained from all respondents of a survey serve as norms to which subgroups of respondents or respondents of future surveys can be compared. These results are often reported as percentages of respondents being satisfied with each item. Although the MarkeTrak has been conducted about five times over the past 15 years, no data on reliability and validity has been reported. Nevertheless, it has been regarded as one of the most informative satisfaction measures. Its advantage rests on extensive sampling, and provision of data for comparison across various characteristics at different times. The SADL and the MarkeTrak measure similar constructs, mainly dealing with listening and benefit in various situations, sound quality, cost, reliability of the product and services obtained. Value, as measured under the Product Feature category on the MarkeTrak, refers to the performance of hearing aids relative to price and perceived performance. Thus, value, together with reliability of the hearing aid, are related to the Service and Cost subscale of the SADL. The Service factor of the MarkeTrak is also assessed under the Service and Cost subscale of the SADL. Items from the MarkeTrak that evaluate problems in hearing aid use, such as feedback, are reflected in the SADL’s Negative Feature subscale. Sound quality and listening in multiple situations on the MarkeTrak are similar to the SADL’s Positive Effect subscale. Humes et al (2002b) found global SADL scores on a population with one month of hearing aid use experience comparable to MarkeTrak IV norms. Global MarkeTrak IV scores correlated moderately with global SADL scores (r = .75, p < .01), but less with SADL subscale scores (r = .42 to .62, ps< .01) Other studies have employed hearing aid satisfaction measures (e.g., Stock et al, 1997) that have not been evaluated as extensively as the MarkeTrak and the SADL. Table 3 Wong, Hickson & McPherson Hearing Aid Satisfaction 8 lists descriptions of a few common hearing aid satisfaction measures and Table 4 provides a list of all hearing aid satisfaction measures used in the studies reviewed in this paper. Nonetheless, these studies have revealed important findings about how hearing aid satisfaction relates to many factors such as type of hearing aid, sound quality, listening environment, benefit, experience and attitude, expectation, counseling, and usage. These findings are summarized in Tables 5 and 6 and will be discussed in the following three sections. The Appendix contains information on the research methodologies, aims and findings of these studies. Methodologies of hearing aid satisfaction studies A total of 45 studies were reviewed. Table 4 summarizes the types of hearing aid satisfaction measures in the various studies. General satisfaction was measured in 32 studies; satisfaction in specific aspects (e.g., cost, reliability, performance) was measured in 19 studies. Most studies used a categorical scale, although sometimes the categorical scale was associated with a numeric scale. For example, the SADL employs seven-point categorical scale of this kind. Depending on the location where the study was conducted, different measures were used. For example, many studies from the United States employed the MarkeTrak or the SADL. These are the most commonly used measures, appearing nine and five times in the studies described here. Eight Australian studies used the Hearing Aid User’s Questionnaire (HAUQ), while other countries used a mix of measures. Because satisfaction is a perception, self-report measures are used to assess it. Other outcomes such as benefit, problems, usage, service, disability, handicap, are measured by using either self-report or objective tools such as speech recognition tests and pure-tone thresholds. Wong, Hickson & McPherson Hearing Aid Satisfaction 9 Table 4 also summarizes the demographic details of participants in the various studies: • Most studies were conducted in the United States, with a small proportion from Australia, Europe and New Zealand. Most studies were performed on a participant pool of less than 200; however, a few studies were very large scale, with data collected mostly with the MarkeTrak Satisfaction Survey (e.g., Kochkin 2000a). Studies by Dillon et al (1999) and Parving et al (2003) included more than 4000 and 14000 participants, respectively. • Most participants were elderly with a mean age of 65 or above. • Four studies examined satisfaction in new users, a few studies compared results from experienced and new users (e.g., Cox and Alexander, 2000; Kochkin, 2000a), but others did not discriminate between these two types of users (e.g., Gatehouse, 1994; Hickson et al, 1999). A few other studies evaluated experienced users only (e.g., Newman and Sandridge, 1998). • Whether participants had binaural fitting was not stated in most studies and we assume that no differentiation between these participants was made. • Ten studies focused on particular styles of instruments, others reflect results from various styles. Three studies reported satisfaction with digital hearing aids. Participants have various degrees of loss but direct comparison cannot be made across studies as some studies have reported average hearing level only (i.e., Gatehouse, 1994; Brooks and Hallam, 1998), and some reported hearing in the better ear (e.g. ̧ Brooks and Hallam, 1998; Purdy and Jerram, 1998). • Test intervals were specified in 25 studies, spanning from 1 or 2 weeks to 4 years post fitting, with the majority assessing satisfaction in the first year. With the exception of the studies by Bentler et al (1993), McLeod et al (2001), and Humes Wong, Hickson & McPherson Hearing Aid Satisfaction 10 et al (2002a), all were cross-sectional investigations. The Appendix details research studies on hearing aid satisfaction. The studies can be divided into three categories according to their purposes: (1) Development and validation of the measurement scales (i.e., Cox and Alexander, 1999, 2001; Hosford-Dunn and Halpern, 2000; Humes et al,