Portuguese Version

Year:  2002  Vol. 68   Ed. 1 - (5º)

Artigo Original

Pages: 28 to 33

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Assessment of the elderly auditory processing with and whithout presbicusis by ssw test

Author(s): Sandra Murad Quintero 1,
Rosely M. B. Marotta 1,
Sílvio A. M. Marone 2

Keywords: elderly, speech intelligibility, presbycusis.

Abstract:
Introduction: For a human being, the communication is an essential act in his life and thus, the preservation of auditory capability is vital. With the growth of life expectancy arises the need to understand better elderly people and their constant complaint of not understanding the speech in noisy environment, or in the environment with reverberation. Many writers relate this difficulty to the neurossensorial auditory loss frequently found in these people. However, in many cases this difficulty seems worse than the expected in view of the amount of hearing lost. This fact is not usually detected by conventional tests of tonal and vocal audiometry which provides the data relative to the auditory loss of the individual without describing how this loss affects his life, his day-by-day communication. Aim: To assess and compare the auditory performance of elderly people, both with normal hearing and with neurossensorial auditory loss characteristical of presbycusis, by SSW Test. Study design: clinical prospective randomized. Cases and method: 100 elderly people have been assessed, aged from 60 through 79. Of this number, 50 individuals showed neurossensorial auditory loss characteristical of presbycusis (a study group) and 50 elderly individuals with tonal hearing within normal standards (a control group). Before applying SSW test, these people had undergone anamnesis and audiologic and otorhinolaryngologic evaluation. Conclusion: No statistically relevant difference has been found between both groups. However, there was a tendency of worse performance of the study group under studied conditions. Thus, we found that the neurossensorial auditory loss cannot be considered as determining factor, but rather as an aggravating one in the elderly difficulty to understand the person's speech.

1 Audiologist, Master in Sciences, Medical School of University of São Paulo, working at the Sector of Audiology, Clínica Otorhinus-SP.
2 Professor, Ph.D., Department of Otorhinolaryngology, Medical School of University of São Paulo, director of Clínica Otorhinus- SP.

Study conducted at Clínica Otorhinus - Centro de Diagnose em Otorrinolaringologia de São Paulo

Address correspondence to: Sandra Murad Quintero - Rua Embaixador Ribeiro Couto, nº 351 - Moema - 04517-110 - São Paulo/ SP - Tel: (55 11) 5535-8006.- E-Mail: sandramq@uol.com.br

Article submitted on October 15, 2001. Article accepted on November 21, 2001.

INTRODUCTION

There is a large number of people over 60 years of age who have considerable difficulty to understand speech.

The population over 60 years of age in Brazil is greater than 10 million people, a figure that ranks the country among those who have the largest elderly populations in the world26.

Brazil is no longer a country of youth and age has become a factor of social discrimination. Communication is an essential act of human life and hearing skills should always be preserved.

As a result of increased life expectancy, we have to start to understand better the elderly.

Aging affects the social relationship of the elderly owing to psychophysical factors and social-culture nature, developing a characteristic process in the elder population of self-undervaluing and low self-esteem, aggravated by the communication difficulty.

Alterations resultant from aging are not uniform and affect the whole body30.

Presbycusis is characterized by high-frequency bilateral hearing loss owing to degenerative and physiological alterations to the auditory system as a result of aging4.

Sensorineural hearing loss (SNHL) is frequently detected in the elderly, as referred by different authors as the main factor to explain speech understanding difficulties of this population28, 16, 13.

In many cases, however, the communication difficulty reported by the elderly seems to be worse than expected based on the severity of the loss. Conventional audiometry (pure tone and vocal) provides data about hearing loss, but it does not describe quality of life or daily communication. Some authors wonder if the hearing loss is caused only by peripheral impairment or whether there is some central affection as well, reproducing a wide range of alterations, amounting to a cumulative final effect15, 2, 22, 12. SNHL was considered an aggravating factor to central auditory processing disorders (CAPD) by Diveneyi and Haupy (1997)7.

Speech understanding models proposed multiple sound perception and transmission processes by means of a series of processing steps, for final understanding at the cortical region.

The different changes that impair the auditory nervous system of the elderly possibly interfere in the capacity the elderly has to efficiently process the receiving speech, determining difficulties in speech understanding, regardless of the severity of SNHL 8, 9, 27, 30, 29.

The elderly normally show the need to take more time to process receiving information1, 10. The processes' speed may affect the skills required to keep a normal convention regardless of auditory sensitivity.

The difficulty the elderly present to understand speech in the presence of other simultaneous sounds is explained by tests specifically designed to assess speech understanding in noise or in a reverberating environment.

Many authors6, 11, 17, 23 reported that there are differences in measuring speech understanding in the elderly, in noise and in the presence of reverberation, from other measures in silence, and they suggested that the tests should become part of the audiological battery to assess auditory functions of the elderly.

Conventional audiometric measures are not sufficient to describe the reaction of the patients concerning the hearing loss and their skills for daily living communication and psychosocial function5.

The main reason for suggesting auditory processing assessment is the lack of information of individual communication provided by conventional audiometry.

Central auditory processing disorder (CAPD) is a rupture in one or more than one steps of auditory processing, generating a hearing disorder in which there is an impairment to analyze and interpret sound patterns, which may be a result of sensorial deprivations, hearing losses, neurological problems, and others24.

SSW test was described by Katz (1962)19 and adapted to Portuguese by Borges (1986)3. The selection of this test was based on its easy and quick applicability, and because it is not influenced by peripheral hearing losses3, 20, making it a very reliable tool for the study of the elderly.

The change in terminology from central auditory processing disorders (CAPD) to auditory processing (AP) was suggested by Jerger; Musiek (2000)18, because it emphasizes interactions of the disorders both in the peripheral and the central portions, differently from defining a specific anatomical site.

Considering that high frequency hearing losses, characteristic in presbycusis cases, may impair the performance of AP skills, we investigated whether it was a determining factor for AP abnormality in the elderly, or if aging central nervous system affections per se would justify the constant complaint of the elderly of not understanding speech in noise and reverberated environments, not explained by means of basic audiological assessment.

Material and method

We evaluated 100 subjects from Clínica Otorhinus - Centro de Diagnose em Otorrinolaringologia de São Paulo, divided into two groups.

The control group consisted of 50 subjects, ages ranging from 60 to 79 years, 10 men and 40 women, presenting pure tone thresholds in frequencies 0.25,0.50, 1, 2, 3, 4, 6 and 8kHz £ 25 dB HL.

The studied group consisted of 50 subjects, ages ranging from 60 to 79 years, 21 men and 29 women, with bilateral symmetrical sensorineural hearing loss, characteristic of presbycusis, with pure tone audibility thresholds ranging from 30 to 60dBHL, considering frequencies 4, 6 and 8kHz and frequencies 0.25, 0.50, 1 and 2kHz £ 25 dB HL; audiometric curve configuration symmetrical in both ears, with interaural audibility threshold difference of £ 15 dB HL, absence of air/bone gap, speech reception thresholds (SRT) £ 25 dB HL.

We tried to match subjects in the control and studied groups according to age.

All subjects were right-handed, spoke Portuguese as maternal language and were fluent in reading, regardless of educational level. Speech Reception Thresholds (SRT) £ 25 dB HL, Perceptual Speech Recognition Index (IPRF) = 100 % of correct identifications and imitanciometry with normal curve Type A14, in addition to presence of contralateral reflex in both ears in frequencies of 0.50, 1, 2, and 4kHz, were required.

Criteria for exclusion in both groups were:

· Middle ear affections;
· History of ear or brain surgery;
· Central damage;
· Subjects who had already participated in auditory stimulation;
· Presence of neurological or emotional disorders;
· Subjects who used illegal drugs, alcohol, antidepressant drugs or any drugs that had effects on the central nervous system.

All subjects were submitted to audiological history, ENT assessment and audiological assessment (pure tone audiometry, vocal audiometry and imitanciometry) in order to investigate data about auditory performance of subjects and to exclude diseases that could interfere in the study. We asked the subjects to sign a Term of Informed Consent. SSW test adapted to Portuguese3 was applied using the compact disk volume 2, track no. 6 that comes with the manual of instructions25. We used the audiometer Madsen-Midimate 602, phones TDH-39 and MX- 41, appropriately calibrated.

The test was performed at 50 dBSL considering the mean of frequencies 0.50, 1 and 2kHz or the most comfortable intensity, ranging from 55dBHL to 75dBHL.

The quantitative analysis of the results was performed for the conditions Right Competitive (DC) and Left Competitive (EC) and the qualitative conditions of Auditory Effects (EA), Order Effect (EO), Inversions (Inv.) and Type A.

Graph 2. Distribution of the percentage of conditions for the SSW test, decreasing order of alteration, in the control and studied groups.

Graph 3. Results of the comparative analysis of normal and abnormal findings in the SSW test.

The normal range was based on Katz description (1996)21.

Acoustic analysis was performed using Wilcoxon-Mann-Witney test, Chi Square Test and/or Fisher exact test.

We determined the level of 0.05 or 5% to reject the null hypothesis of all results.

The present study was approved by the Ethics Commission of project analysis - CAPPESQ, from Hospital das Clínicas and from FMUSP, under protocol number 367/99.

RESULTS

In order to better understand data, we decided to initially present distribution of numbers of errors in absolute values, means (x), standard deviations (SD) and medians (M), for each studied condition both for the control and the studied group, respectively, shown in Tables 1 and 2. We noticed an increase in the mean number of errors in most conditions evaluated in the studied group (Graph 1).

Next, we presented the results of the comparison between the groups concerning number of errors in absolute values for each studied condition (Table 3). There was no statistically significant difference between the groups in the studied conditions.

In Graph 2, we observed the percentage distribution of conditions of SSW test, in decreasing order of alteration, in the control and studied groups. We observed higher percentage of alterations in the conditions DC and EC for both groups.

As to analysis of normal and abnormal findings in the SSW test, considering abnormal the cases that presented one or more abnormal conditions, and normal as the cases that did not present any abnormal condition, we detected an occurrence of 60% of abnormal cases in the control group and 66% of abnormal cases in the studied group (Graph 3).

DISCUSSION

The conduction of the present study was the result of the observation of many cases of difficulty in speech understanding by the elderly in normal hearing conditions, making us wonder whether the difficulty was related with the hearing loss presented by the patients or with auditory processing disorders related to aging.

Speech understanding difficulties by the elderly may be related to the inability to efficiently process the receptor speech.

Upon the analysis of the conditions concerning the number of errors in absolute values (Table 3), there was no statistically significant difference in any of the studied conditions comparing the two groups, demonstrating similar level of alterations in both groups. Thanks to the observation of mean values (Graph 1), we detected worse performance in the studied group in the majority of the studied conditions.

Based on such data, we can realize that SNHL may not be considered as the determining factor in AP disorders of the elderly, but they may be seen an aggravating factor, in accordance with the findings by Diveneyi; Haupy (1997)7 and disagreeing from the data by Solomon et al. (1960)28, Jerger et al. (1991)16 and Humes et. al (1992)13.

In Graph 2, we could observe that the conditions that were affected the most, in both ears, were DC and EC which are conditions in speech competitive environment, which is in agreement with the complaints of the elderly of not understanding speech in noisy and reverberating environment.

As to findings of normal and abnormal results in SSW test, considering them abnormal if the case had one or more abnormal conditions, whereas it was considered normal when no conditions were abnormal, we noticed similar performance in the groups, and the control group presented 60% of abnormal cases and the studied group, 66% (Graph 3).

In our study, most of the cases of the control group presented abnormalities in the SSW test, considering the normal ranges established by Katz (1996)21. Therefore, we may infer that the age factor suggests AP abnormalities regardless of SNHL level.

Speech understanding models proposed multiple processes of transmission and reception of sounds, by means of a series of processing stages for final interpretation at the cortical region.

The main differences that occur under the organic and physiological aspects of the auditory system of the elderly8, 9, 27, 29, 30, both for the central and peripheral portions, possibly interfere in the elderly ability to efficiently process receptive speech, frequently generating speech understanding difficulty, regardless of SNHL severity.

Based on such analysis, we believe it is not convenient to use only one procedure to diagnose AP in the elderly. The inclusion of other procedures, including electrophysiological methods, becomes necessary for a more precise assessment18.

The audiologist should be fully aware of all harmful effects of AP disorders to elderly subjects concerning communication function, especially if the patient has as aggravating factor the presence of SNHL, in order to help him or her to establish the best possible communication.

A more comprehensive understanding of the communication problems of the elderly patients is vital to perform good preventive management and successful social reintegration.

CONCLUSION

· There was no statistically significant difference between the groups; however, there was a trend towards worse performance of subjects with presbycusis, under the studied conditions.
· Sensorineural hearing loss is not a determining factor, but rather an aggravating factor for speech intelligibility in the elderly in noisy and reverberation environments.
· Abnormalities resulting from aging per se were not seen as hindrance to effective processing of data.
· For a more precise assessment about auditory processing disorders of the elderly, we believe that other assessment protocols should be included in the routine assessment procedures.

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