Systematic analysis of the benefits of cochlear implants on voice production

Abstracts

OBJETIVO: Realizar uma revisão sistemática de pesquisas relacionadas às características vocais de crianças ou adultos com deficiência auditiva usuários de implante coclear. ESTRATÉGIAS DE PESQUISA: Foi realizada uma busca com os descritores voz, qualidade da voz e implante coclear, e seus respectivos correspondentes na língua inglesa, nas bases de dados Web of Science, Bireme, portal de teses e dissertações da USP e banco de teses e dissertações da CAPES. CRITÉRIOS DE SELEÇÃO: Os critérios adotados incluíram título condizente com a proposta deste estudo, casuística necessariamente englobando crianças ou adultos com deficiência auditiva de grau severo a profundo, pré ou pós-linguais, usuários de implante coclear e que tenham passado por análise perceptivo-auditiva e/ou acústica da qualidade vocal. RESULTADOS: Vinte e sete trabalhos foram classificados seguindo-se os níveis de evidências e indicadores de qualidade empregados pela American Speech-Language-Hearing Association (ASHA). Os desenhos dos trabalhos analisados foram considerados de média e baixa evidência científica. Seis trabalhos foram classificados como nível de evidência IIb, 20 como III, e um como IV. CONCLUSÃO: A qualidade vocal da criança ou adulto com deficiência auditiva usuário de implante coclear tem sido estudada em pequena escala. Não há um número efetivo de estudos com alto índice de evidência que demonstrem com precisão os efeitos do implante coclear na qualidade vocal desses indivíduos.

Voz; Qualidade da voz; Distúrbios da voz; Transtornos da audição; Implante coclear

EVIDENCE-BASED SPEECH-LANGUAGE PATHOLOGY AND AUDIOLOGY

Systematic analysis of the benefits of cochlear implants on voice production

Ana Cristina Coelho^I; Alcione Ghedini Brasolotto^II; Maria Cecília Bevilacqua^II

^IGraduate Program (Master's degree) in Speech-Language Pathology and Audiology, Bauru School of Dentistry, Universidade de São Paulo - USP - Bauru (SP), Brazil

^IIDepartment of Speech-Language Pathology and Audiology, Bauru School of Dentistry, Universidade de São Paulo - USP - Bauru (SP), Brazil

^{Correspondence address}

ABSTRACT

PURPOSE: To perform a systematic analysis of the research regarding vocal characteristics of hearing impaired children or adults with cochlear implants.

RESEARCH STRATEGY: A literature search was conducted in the databases Web of Science, Bireme, and Universidade de São Paulo's and CAPES' thesis and dissertations databases using the keywords voice, voice quality, and cochlear implantation, and their respective correspondents in Brazilian Portuguese.

SELECTION CRITERIA: The selection criteria included: title consistent with the purpose of this review; participants necessarily being children or adults with severe to profound pre-lingual or post-lingual hearing loss using cochlear implants; and data regarding participants' performance on perception and/or acoustic analysis of the voice.

RESULTS: Twenty seven papers were classified according to the levels of evidence and quality indicators recommended by the American Speech-Language-Hearing Association (ASHA). The designs of the studies were considered of low and medium levels of evidence. Six papers were classified as IIb, 20 as III, and one as IV.

CONCLUSION: The voice of hearing impaired children and adults with cochlear implants has been little studied. There is not an effective number of studies with high evidence levels which precisely show the effects of the cochlear implantation on the quality of voice of these individuals.

Keywords: Voice. Voice quality. Voice disorders. Hearing disorders. Cochlear implantation

INTRODUCTION

The main focus of the speech-language pathologist's work with individuals who are deaf and hard of hearing does not always include voice production. However, the vocal alteration can represent a very negative impact, interfering on speech intelligibility and decisively compromising social integration⁽¹⁾.

The cochlear implant (CI) provides global benefits on hearing perception, and consequently on expressive and receptive language, including improved vocal quality. It results on the optimization of speech perception, and therefore on the verbal communication of its users. Hence, the CI is known to be one of the most promising and effective technologies to remedy hearing loss^(2,3).

Extensive literature shows that the cochlear implant, in addition to all the hearing benefits, brings also great advantages for voice production. The most reported findings are improved noise and perturbation measures^(4-7), phonatory control^(4-7), fundamental frequency^(5,8), roughness and strain⁽⁹⁾, and pitch⁽¹⁰⁾. However, some studies did not find significant changes on the voice production of individuals who are deaf and hard of hearing and use cochlear implants^(11-13).

A literature review directed to the methodological aspects of these papers may help to understand these results, and serve as a guideline to what needs to be better explored. The present investigation is a systematic review, which consists on the application of scientific strategies that aim the critical evaluation and synthesis of a large number of studies on a given topic. Its relevance is the ability to condense and summarize results of several studies, producing different quantitative and qualitative indicators on the topic researched^(14-16).

OBJECTIVE

The purpose of this study was to perform a systematic review of researches related to the vocal characteristics of children and adults who are deaf or hard of hearing and use cochlear implants.

RESEARCH STRATEGY

To perform this systematic review, we followed the concepts of the online course promoted by the Brazilian Cochrane Center and by the Laboratory of Distance Learning - LED-DIS of the Department of Health Informatics of Universidade Federal de São Paulo/Escola Paulista de Medicina, available at http://www.virtual.epm.br/cursos/valida.php. The literature review was based on the question "What are the effects of cochlear implants on the voice of individuals who use this device?"

To search for studies, we used three key-words from the Health Science Descriptors (DeCS) and four key-words from the Medical Subject Heading Terms (MeSH). The DeCS terms used were "voz" (voice), "qualidade da voz" (quality of voice) and "implante coclear" (cochlear implant). The MeSH terms were "voice", "voice quality", "cochlear implant" and "cochlear implantation". We used different combinations of these terms (Chart 1), with the connector "AND".

The bibliographic research (Table 1) was performed in the databases Web of Science (www.isiknowledge.com); Bireme - Virtual Health Library - BVS (www.bireme.br), comprising the databases LILACS, MEDLINE, Cochrane Library, SciELO and IBECS; Digital library of theses and dissertations of the Universidade de São Paulo (http://www.teses.usp.br/); and CAPES's digital library of theses and dissertations (www.capes.gov.br/servicos/banco-de-teses). There was no restriction regarding the publication year.

SELECTION CRITERIA

A pre-selection of all the publications/studies whose title seemed to be related to the question proposed in this systematic review was performed. To be analyzed, the study should necessarily include children or adults with severe to profound hearing loss, pre- or post-lingual, using cochlear implants. Another selection criterion was the performance of auditory-perceptual and/or acoustic analysis of the voice of the CI users.

We excluded duplicated publications (85), publications whose full texts were not found (13), whose language was not Portuguese or English (15) and whose content did not correspond to the purpose of this review (2354). At the end of the search, 27 relevant publications remained for the systematic review, which included a letter to the editor and two master's thesis. The others referred to published studies, 2 performed in Brazil and 22 in other countries.

DATA ANALYSIS

All the publications were analyzed and classified following the levels of evidence employed by ASHA in 2004, adapted from the Scottish Intercollegiate Guideline (Chart 2). Moreover, the studies were analyzed based on a proposal^(16,17) of eight quality indicators to evaluate studies, which include: the study design, blinding, sampling/allocation, group/participant comparability, outcomes, significance, precision and intention to treat.

Chart 3

RESULTS

Regarding the levels of evidence, six studies were classified as IIb, 20 as III, and 1 as IV. The designs of the studies found were considered of good and lower scientific levels, although it is important to consider that non-experimental studies have great value for understanding a certain subject.

Regarding the quality indicators, 23% of the studies are quasi-experimental and 77% are non-experimental; 66.67% present groups that are comparable and adequately described; 70.78% present valid and reliable outcomes; in 85%, the confidence interval is calculable and the p-value is reported; there are evidence of randomization and blinded assessors in 29.62% of the publications. The intention to treat^(6,7) was not considered, since this indicator applies only for controlled trials.

The heterogeneity of the methods used in the studies makes it difficult to understand how the use of cochlear implants can benefit the vocal quality of individuals who are deaf and hard of hearing. The results of the studies are diverse and often controversial (Chart 4). In many cases, the importance of understanding the voice of the individual with a CI is not clear.

Although all the studies unanimously report that the use of the CI provide some benefit for voice production, the reports of these benefits are inconsistent. Factors such as the advantages provided by the CI for voice production, improving oral communication and how these advantages can help in a therapeutic process, or even how they can be considered as one of the many criteria to decide which device will be used, are not well described.

We noticed predominant use of Kay Elemetrics' softwares (48.14%) in case of acoustic analysis of the voice signal as a part of the methodology. Eight studies (29.62%) involved auditory-perceptual evaluation of the voice, all with evidence of randomized samples and blinded raters. One study considered the different types of cochlear implants in the evaluated population.

CONCLUSION

With this review, it was possible to observe that the quality of voice of children and adults who are deaf and hard of hearing and use cochlear implants has been studied on a small scale. There is not an effective number of studies with high levels of evidence that demonstrate precisely the effects of the cochlear implant on the quality of voice of children and adults who are deaf and hard of hearing.

To improve the quality of the studies regarding scientific evidence, the studies must be carefully designed, with a significant number of participants, according the possibilities of the centers in which they are performed. Moreover, a methodology based on the quality indicators proposed by ASHA should be adopted in future studies about the theme.

AKLOWLEDGEMENTS

The authors would like to thank the São Paulo Research Foundation (FAPESP), for the financial support, process n^o. 2008/07948-1.

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Conflict of interests: None

Received: 3/5/2012

Accepted: 7/17/2012

Study performed at the Graduate Program in Speech-Language Pathology and Audiology, Bauru School of Dentistry, Universidade de São Paulo - USP - Bauru (SP), Brazil.

Publication Dates

• Publication in this collection
  07 Jan 2013
• Date of issue
  2012

History

• Received
  05 Mar 2012
• Accepted
  17 July 2012