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Year: 2007  Vol. 11   Num. 2  - Apr/June Print:
Original Article
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Speech Discrimination Index in Presbycusis
Índice de Reconhecimento de Fala na Presbiacusia
Author(s):
Ana Tereza de Matos Magalhães1, Maria Valéria Schmidt Goffi Gómez2
Key words:
Presbycusis. Aged. Hearing. Hearing loss sensorineural. Tearing tests.
Abstract:

Introduction: Presbiacusis has been mentioned as a main reason for the difficulty in speech understanding in elderly people. Nervertheless, clinical experience shows that elderly people presenting sensorineural hearing thresholds may present different speech recognition scores. Objectives: The aim of this study was to verify the hearing thresholds and the speech recognition score in elderly patients presenting presbiacusis. Material and Methods: The sample was composed of elderly patients referred to audiometry in the ENT department of Hospital das Clínicas of FMUSP. Fifty files were analysed, twenty seven males and twenty three females with average age of 73,6 years old. Results: The most frequent bilateral symmetrical sensorineural hearing losses found were with mild (41%) and moderate degrees (36%). Conclusions: The Pbmax scores varied among the patients, regardless of the degree of the hearing loss. In some cases the speech discrimination was poor and the hearing loss was mild; and in some other patients the speech discrimination was normal in moderate to severe hearing losses.

INTRODUCTION

The life expectancy has been increasing in all world-wide population. In Brazil the number of elderly people who are older than 60 years old exceeds 10 million(1). Thus, the necessity to better understand the alterations produced by the aging process appears, since they occur in some systems of the organism, among which the hearing.

The communication is a basic act in life, being the hearing an important factor so that it effectively occurs. The auditory due to age has negative impact in the life quality of these individuals, once it interferes with communication, mainly in noisy environments, making the social relations difficult.

The auditory loss is one of the most frequent chronic problems found in the aged ones and tends to increase with age, affecting 33% of those between 65 and 74 years old, 45% of the people between 75 and 85 years old and 62% of the people above 85 years old(2).

Presbyacusis is the term which refers to the aging process in relation to auditory loss, occurring in both genders(2). It appears from 60 years of age and depends on some factors. Both endogenous factors, as hereditary or heredity illnesses (for example: diabetes and hypertension), as exogenous factors, nutrition, stress and exposition to noise can influence the hearing loss(3).

The presbyacusis audiogram is initiated with auditory loss in the highest frequencies, later the lowest frequencies are also affected(3). That is, generally the hearing is normal in the 250 to 2000 Hz frequencies, with gradual decline for a mild auditory loss in high frequencies in women and more abrupt moderate auditory loss in men(2). Beyond these characteristics, the performance of the speech intelligibility may be around 35%(4).

Despite its high incidence, there is no way to prevent, to cure or to discover the causing factor of presbyacusis, it is only known that it appears and it is inevitable.

Schuknecht(5) described four classifications of presbyacusis: sensorial, which is characterized by the loss of ciliated cells and atrophy of the auditory nerve in the basal turn of the cochlea. The audiogram is characterized by auditory loss with abrupt fall in high frequencies and a proportional reduction on the ability of speech recognition. The neural presbyacusis is associated with the primary degeneration of neurons and nervous fibers, with the biggest loss in the base of the cochlea. It is characterized by the disproportionate loss of the ability of speech recognition to the auditory loss for pure tones. The metabolic or vascular stria presbyacusis involves the atrophy of the vascular stria. The audiogram has configuration with plain auditory loss and the speech abilities tend to be intact despite the loss. Finally, mechanic presbyacusis, which involves the hardening of basilar membrane or other mechanical disorders, which interferes with the sound transmission inside the cochlea. The auditory loss is slowly gradual, with descending configuration.

The presbyacusis has been mentioned as main clarifying factor of difficulty of speech understanding in individuals. However, this difficulty reported by the aged seems to be bigger than the expected one for the amount of auditory loss(6). On one hand, in many cases, through the audiometric configuration, auditory prosthetization with good prognostic is recommended. On the other hand, it is observed that even with the sound amplification, the difficulty of speech understanding continues being the most common complaint among these individuals(7).

The speech tests are important means to evaluate the receptive communicative function of the aged in an almost systematic way. They provide objective and easy to quantify on alterations information, derived from the auditory loss and ability of speech recognition in different situations(2).

The speech ability can be evaluated through the logoaudiometric threshold, in which the lowest intensity in which the individual manages to identify 50% of the familiar words that are presented to him/her is investigated. That would be the Speech Reception Threshold (SRT). It can also be evaluated through Speaking Rate (SR) which evaluates the speech discrimination by means of a list of monosyllabic words and disyllabic 40dB above the Speech Reception Threshold (SRT)(8).

In the clinical experience it is common to observe individuals with the same degree and configuration of sensorineural auditory loss which present different SR results(9).

Besides the fact that speech tests provide data on the communicative efficiency of the individuals, they also provide information for the distinguishing diagnosis related to the place of the injury and help in the election of individual auditory prosthesis.

The present work aimed to verify the audiometric degree and configuration and to relate with the speech ability by means of SRT and SR values of individuals affected with presbyacusis.


MATERIAL AND METHOD

This study was approved by Comitê de Ética e Pesquisa - CAPPesp at Diretoria do Hospital das Clínicas and at FMUSP through the protocol number 1042/06.

The sample consisted of patients of the Otorhinolaryngology sector of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo forwarded to the Audiology sector for accomplishment of the audiometry which presented the following criteria of inclusion:

- Individuals who were older than 60 years old, of both genders, based on the criterion established by the Estatuto do Idoso(10);

- Individuals who present audiometric configuration of presbyacusis, that is, bilateral and symmetrical hypoacusia, generally with descending audiometric curve and above of 2000Hz in the initial phase, considering that the serious frequencies can also be affected(11);

- Data of the Logoaudiometria: SRT - the results are expressed in dB, which represent the recognition of 50% of the speech material, and must be found in levels of up to 10 dB above the average thresholds of 500, 1000 and 2000 Hz (Redondo and Lopes Son, 1997). And SR which are expressed in detection rate and consider normal limits between 90 and 100% and modified limits below 89%(12);

- Individuals who do not have otology or ear surgery;

- Individuals who do not carry congenital syndromes or craniofacial malformations.

In the audiometry, the audibility thresholds were classified according to BIAP - (Recommendation number 02/1 bis, 1996)(13) being the average of the auditory thresholds in the frequencies of 500, 1000, 2000 and 4000 Hz:

- normal auditory thresholds: up to 20 dB;

- minimum auditory loss: of 21 dB the 40 dB;

- moderate auditory loss:
Degree 1: from 41 dB to 55 dB.
Degree 2: from 56 dB to 70 dB

- severe auditory loss:
Degree 1: from 71 dB to 80 dB
Degree 2: from 81 dB to 90 dB

- deep auditory loss:
Degree 1: from 91 dB to 100 dB
Degree 2: from 101 dB to 110 dB
Degree 3: from 111 dB to 119 dB

- anacusis: 120 dB

The classification of the SR values were based on Jerger and Speaks (14):

- normal Limits: 100% 92%
- Slight difficulty: 88% 80%
- moderate Difficulty: 76% 60%
- poor Discrimination: 56% 52%
- very poor Discrimination: below of 50%

50 patient medical records which presented the inclusion criteria were investigated, being 27 male and 23 female, with average age of 73,6 years (from 60 to 97 years).

The results have been placed in tables for better visualization.


RESULTS

The presence of minimum, moderate degree I and II and severe degree is observed, being the most frequent minimum degree (41%) and moderate degree I (36%). Comparing the classification of the SR with the minimum auditory loss, it is observed that most is within the normality limits (51%) and light difficulty (32%). However, in the auditory loss moderate degree I equal number of patients with limits which are within normality (25%), fast difficulty (25%) and very poor difficulty (25%) of SR is observed. (Table 1).




In Table 2 the average SR values are found (in %) in the different degrees of auditory loss, in which it is noticed that the value of SR diminishes as the auditory loss increases, however this reduction is small.




The SR data have also been compared with SRT values of patients and average percentage of SR was carried through (Table 3).




In the normal limits of SRT, the SR values are within normality (41%) or with light difficulty (36%). Between 26-40 dBNA most is whithin normality (41%), followed by light difficulty (21%) and very poor discrimination (15%). The 41-55dBNA SRT classification of light difficulty (35%) is more frequent, after normal limits, moderate difficulty and very poor discrimination appear. with same frequency (19%). Between 56-70dBNA, the most frequent difficulty is moderate and very poor discrimination (36.5% each) (Table 4).




DISCUSSION

Predominance of male patients in the total sample with 54% is observed, and female patients with 46%, which agrees to the literature, which observes significantly bigger auditory loss in men(15).

The audiometric configuration was bilateral, symmetrical, descending(16), of minimum and moderate degree I and II and severe degree, which agrees to Baraldi et al(17) findings, who, when comparing elderly patients with and without hypertension, found in the group without hypertension 38.9% patients with light degree and 27.8% with moderate degree and 2.8% with severe degree, resembling the results found in this study.

It is observed that the SRT thresholds which are within normality have the best speech recognition results, which is expected for cochlear alterations. However, the results show that in some cases with the same degree of auditory loss different SR values were found. Despite the increase of the auditory loss, a homogeneous distribution of speech recognition values is found, which vary from the best results (96%) to the worst ones (6%). Even in normal ears percentage of aged patients with poor speech recognition performance were found.

It is believed that there is a decrease in the speech intelligibility performance as age advances. Jerger (18) had already mentioned in his study the disproportion of auditory loss. When the average of auditory loss was between 40-49dB, the maximum value of speech discrimination declines 80% in the group of 10-19 years of age to 60% in the group of 80-89 years. He also suspected that the speech discrimination has more peripheral evidences than central ones to explain this phenomenon.

Yoshioka and Thornton(19) comment that the speech discrimination is very affected when the auditory loss is light, changing the recognition from "very good" to "reasonable" when the slope of auditory loss is steep. For moderate losses to severe ones, all of them presented poor discrimination, however it was possible to observe in our findings that exactly in moderate losses there is great variety in the speech ability.

Studies on the temporal auditory processing of aged patients who complain about difficulty to understand speech show that this ability does not have relation with the level of auditory loss. Pinheiro e Pereira(20) had evaluated the auditory processing in aged patients and found the binaural synthesis ability modified, which would be responsible for understanding in noisy places. Then, the complaint of difficulty of auditory understanding even with a good adaptation to sound amplification device could be explained by a dysfunction of the auditory processing(7). Thus, studies on the auditory processing would be interesting, once the SR is carried through in ideal listening situation, which does not occur in daily reality(21).

Considering so many different speech ability indices in the aged, we find that the classification of Schuknecht(5) is founded and necessary to better understand the differences between the presbycousis.

Although some explanations and suggestions on the relation of poor discrimination and level of hearing exist, what we find is the real difficulty to understand speech in the aged ones, thus harming their communication and consequently affecting their quality of life.


CONCLUSION

The sample presented as average of age 73,6 years, with predominance of male patients (54% and female 46%), with bilateral and descending symmetrical sensorineural loss auditory, of predominantly minimum degree and moderate degree I according to BIAP(13).

The SR values, based on Jerger and Speaks(14), and SRT ones according to auditory loss, presented varied resulted, which shows that even if the auditory loss were minimum, the discrimination was sometimes very poor or in the moderate auditory losses they presented normal limits of SR.


BIBLIOGRAPHICAL REFERENCES

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2. Weinstein BE. Presbiacusia. In: Katz J. Tratado de audiologia clínica. 4ª Edição. São Paulo: Manole, 1999, p. 562-576.

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5. Schuknecht HF. Further observations on the pathology of prebycusis. Arch Otolaryngol, 1964, 80:369-382.

6. Quintero SM, Marotta RMB, Marone SAM. Avaliação do processamento auditivo de indivíduos idosos com e sem presbiacusia por meio do teste de reconhecimento de dissílabos em tarefa dicótica- ssw. Rev. Bras. Otorrinolaringol., 2002, 68(1):28-33.

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9. Caporali SA, Silva JA. Reconhecimento de fala no ruído em jovens e idosos com perda auditiva. Rev. Bras. Otorrinolaringol., 2004, 70(4):525-32.

10. Estatuto do Idoso, 2003 Disponível em: www.serasa.com.br/guiaidoso/107.htm. Acesso em: 15/dezembro/2006.

11. Hungria H. Presbiacusia. In: Otorrinolaringologia 6° Edição. Rio de Janeiro: Guanabara Koogan, 1991, p. 377-381.

12. Frota S. Avaliação básica da audição. In: Frota S. Fundamentos em Fonoaudiologia - Audiologia. 2ª edição Rio de Janeiro: Guanabara Koogan., 2003, p. 41-60.

13. BIAP-Bureau International d'AudioPhonologie, 1996 Disponível em: www.biap.org/biapanglais/rec021eng.htm. Acesso em: 10/novembro/2006.

14. Jerger J, Speaks C,Trammell J. A new approach to speech audiometry. J. Speech hear. Desord., 1968, 33:318.

15. Valete-Rosalino CM, Rozenfeld S. Triagem auditiva em idosos:comparação entre auto-relato e audiometria. Rev. Bras. Otorrinolaringol., 2005, 71(2):193-200.

16. Amaral LCG, Sena APRC. Perfil audiológico dos pacientes da terceira idade atendidos no Núcleo de Atenção Médica Integrada da Universidade de Fortaleza. Fono Atual, 2004, 7(27):58-64.

17. Baraldi GS, Almeida LC, Borges ACLC. Perda auditiva e hipertensão: achados em um grupo de idosos. Rev. Bras. Otorrinolaringol., 2004, 70(5):640-4.

18. Jerger J. Audiological findings in aging. Adv. Oto-Rhino- Laryng, 1973, 20:115-124.

19. Yoshioka P, Thornton AR. Predicting speech discrimination from the audiometric thresholds. J Speech Hear Res., 1980, 23(4):814-27.

20. Pinheiro MMC, Pereira LD. Processamento auditivo em idosos:estudo da interação por meio de testes com estímulos verbais e não-verbais. Rev. Bras. Otorrinolaringol., 2004, 70(2):209-14.

21.Almeida LC. Comportamento auditivo: estudo em um grupo de idosos, 2006 (Tese de Mestrado - UNIFESP - EPM).











1. Speech Therapist
2. Doctor Speech Therapist in Communication Disorders Science by UNIFESP - EPM (Fonoaudióloga da Clínica de Otorrinolaringologia do Hospital das Clínicas da FMUSP)

Hospital das Clínicas - Faculdade de Medicina da Universidade Estadual de São Paulo

Ana Tereza de Matos Magalhães
Address: Rua Santa Cruz, 805 apt 102 São Paulo-SP ZIP- 04121-000

This article was submitted to SGP (Sistema de Gestão de Publicações) of R@IO on April 2, 2007 and approved on April 17, 2007 at 22:49:09.

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