AUDIOMETRY WEBER AND RINNE TESTS AS COMPARED TO PURE-TONE THRESHOLDS • THOMPSON, ALISON Κ., B.A. (SP. & Η. TH.) ( W I T W A T E R S R A N D ) Speech Therapy Department, General Hospital, Johannesburg SUMMARY Results of the audiometric Weber and Rinne tests were compared t o pure t o n e thresholds in 1 8 5 Bantu patients. The frequency of 1 0 0 0 Hz was selected as being most suitable for Weber and Rinne testing. T h e Weber w a s found t o be of limited diagnostic value even w i t h unilateral c o n d u c t i v e losses whilst the Rinne displays a fair degree of efficiency and is of value as a routine supple- ment t o audiometric threshold tests. OPSOMMING Resultate van die o u d i o m e t r i e s e Weber en Rinne t o e t s e is m e t s u i w e r t o o n drempels vergelyk. 1 8 5 - B a n t o e pasiente is as proefpersone gebruik. Die fre- kwensie van lOOOhz is as die geskikste vir die Weber en Rinne t o e t s e gereken. Die Weber is, selfs met eensydige geleidings verlies, van beperkte diagnostiese waarde gevind, terwyl die Rinne 'n redelike graad van doeltreffendheid g e t o o n het en aanvullend b y die o u d i o m e t r i e s e drempel t o e t s e gebruik kan word. At the hearing clinic at Baragwanath Hospital, Johannesburg, routine audio- metric Weber and'Rinne tests were fairly frequently found to be inconsistent with pure tone thresholds. In the present study, a large number of pure tone audiograms were compared with audiometric Rinne and Weber results. In recent years, very little has appeared in the literature concerning the Weber and Rinne tests. That which has appeared deals almost exclusively with testing by means of tuning forks. Most authors stress the need to include the Weber and Rinne in a battery of tuning fork tests including the Schwabach and Gelle t e s t s . 1 ' 3 , 6 , 8 , 1 1 , 1 ? Reliability of these tests has been questioned by these workers but they are nevertheless considered to be useful in supple- menting audiometric results. Testing by means of the audiometric bone vibrator has certain advantages over testing by means of tuning f o r k s . 2 , 8 , 1 3 The bone vibrator maintains its , intensity output at any desired level, whereas the tuning fork fades rapidly in intensity, especially in the high frequencies. 1 1 In addition, the bone vibrator permits a standard presentation which is independent of the ear of the o p e r a t o r . 5 , 1 3 MATERIALS AND METHODS Hearing assessments of 185 South African Bantu of both sexes with an age range of 12 to 75 years were analysed. These were taken randomly from the Tydskrif van die Suid-Afrikaanse Vereniging vir Spraak- en Gehoorheeikunde, Vol'. 21, Desember 1974 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) 64 Alison Κ. Thompson records of patients tested at the hearing clinic over an 18 month period. A Maico MA-10 audiometer calibrated to I.S.O. 1964 hearing threshold levels ' was used for testing. The test room was not ideally soundproofed despite the fact that it was lined with acoustic board. Conventional pure tone air- and bone-conduction audiograms were obtained for each patient. Both the Weber and Rinne were tested at an intensity of 15 dB above the patient's threshold of audibility (vibrator placed on the midline of the forehead).8 This is sufficient intensity for clear audibility yet it mini- mises cross-hearing by being close to the patient's threshold. Testing by the Weber and Rinne methods at several frequencies was con- sidered laborious and unnecessary. A test frequency of 1000 Hz was investi- gated and finally utilised for the following reasons: 1) An increase in the force of vibrator application results in an improved, threshold. The greatest change in intensity due to differential force occurs at 250 Hz whilst only slight changes occur at 1000 H z . 4 · 9 2) Middle ear lesions influence the vibratory mechanism of the inner ear thereby providing an artefact of poorer bone conduction thresholds.1 Although this phenomenon is not yet fully explained, it appears to occur most frequently in the lower frequencies where the conductive loss is generally at a m a x i m u m . 7 3) With lower frequencies the Rinne is more likely to be negative in normal ears whereas the reverse is true with higher frequencies. 1 1 The centrally situ- ated 1000 Hz is hypothetically more reliable. 4) With frequencies below 1000 Hz there is a possibility of confusion between the tactile sensation and hearing. This is enhanced with presentation at higher intensities. 5) A frequency of 1000 Hz is situated at the centre of the critical frequency range, and is likely to reflect most successfully both conductive and sensori- neural losses. 6) Tones below 1000 Hz appear to be most affected by ambient noise. This assumes importance when the test environment is not completely soundproof. In Rinne testing a conductive loss of 15 dB reverses the response at ± 500 Hz (i.e. B-C better than A-C), whilst a 20 dB loss is required to reverse the response at 1000 H z . 1 0 The test is thus slightly less sensitive at 1000 Hz. How- ever, as the levels of OdB to 20 dB are considered to constitute the normal hearing range, the required sensitivity is present. The audiograms were classified by two audiologists into 11 broad categories of bilateral hearing characteristics. (Refer to categories listed in Tables I and II). Conventional interpretation criteria were applied. Those classified dif- ferently were discarded. Two assessments were made regarding the Weber and Rinne results in relation' to each audiogram: 1) Correct/error according to the characteristic of air- and bone-conduction thresholds at 1000 Hz only. Journal of lhe South African Speech and Hearing Association, Vol. 21, December 1974 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) Audiometric Weber and Rinne Tests and Pure-Tone Thresholds 65 2) Correct/error as to whether the results reflected the total loss charac- teristics of the given ear/s as indicated by thresholds over the range of 250- 8 000 Hz'. Criteria for assessment of the Weber test were based on research by G r o e n . 1 · 3 · 7 Lateralisation appears to involve the recognition of interaiiral phase and time as well as intensity differences. Lateralisation occurs iri normal ears owing to: a) One stronger vibrating cochlea, as a result of better sound conduction to that cochlea. b) A phase difference between the two sound waves entering the cochleae, the bone conducted tone being lateralised in the cochlea with the leading phase. In normal ears (owing to slight anatomical differences) phase advances may overcome relative amplitude deficiencies of up to 6 dB. Owing to this pheno- menon, a 5 dB amplitude difference between bilateral ear thresholds was accepted in the obtaining of a midline response. Lateralisation was expected at differences of 10 dB or above. Criteria for assessment of the Rinne test were based on the findings of S h e e h y . 1 0 At 1 000 Hz an air-bone gap of less than 20 dB is accompanied by a Rinne positive response. A Rinne negative response occurs with a gap of 20 dB or more. Theoretically, there is a point around 20 dB where both A-C and B-C appear equally loud. This "indifferent" Rinne was accepted as correct with an air-bone gap of 20 dB only. RESULTS AND DISCUSSION Tables I and II summarise the results in the present study. These were ana- lysed statistically using the Cochrans Q test, binomial test and Poisson test. The results at 1 000 Hz only were compared with the total results for each audiogram in order to determine whether the result at 1 000 Hz only was able to reflect the total loss characteristics of the ear/s. For both the Weber and Rinne tests there was no significant difference between the total results and the results at 1 000 Hz only (p < 0,05). Testing at 1 000 Hz is therefore suitable as a test frequency although, clearly, it cannot indicate precipitous high or low frequency loss. The Weber test is generally far less efficient than the Rinne test. This is demonstrated by the finding that in the Weber test, three loss combinations demonstrated highly significant response errors (p < 0,005). These were bilateral normal (A), bilateral equal sensori-neural (E) and bilateral conductive ears (C). These findings are interesting in that combinations A (56,3% error*) and Ε (55,5% error) have bilaterally equal cochlear reserve and the Weber response should therefore be central. That this does not occur indicates that * All percentages apply to results at 1 0 0 0 Hz o n l y . Tydskrif van die Said-Afrikaanse Vereniging vir Spraak- en Gehoorheeikunde, Vol. 21, Desember 1974 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) A lison Κ , T hom pson ο e las Λ M v . Q o o " J T3 ι Ο Ο Ο 73 Χ ) ^ [Λ ο "Ο ^ % » 3 Μ Ο Ο - Ο ο £ " ω e 3 Ο '' ° £ Ο οζ. οο Ο Ο cm ζ . C ο Ν τ; Ο Ο ο e ο 3 Ζ Ο Ό , Ο •υ ω ω ο "3 -α ο — ' •s α. = ; ο ω as J2 ω 3 "Ε "ε 01 7) ; Ν 8 Λ 8 .3 Η XJ _ C £ ο 2 S Λ ^ -t- 1 C PrH (L> ο Η w Ο C5 θ" V ΝΟ Νθ" Γ-1 η CO — kH CO s ε δ oa Ζ ο ο" ν Ο Ο , θ" V Ο ο Ζ £ ο ο ο" ν ο CM ο CM ο <υ — > CO £ 3 CO — C C Ο D U oa en" Ο N O ο CN) ra S ο ίϋ C/2 ^ ^ C3 Ο I- - — vi 00 -g — 3 • - "O o _e ^ ο tn ^ Ο 00 Ο ο Ο Ο ΪΛ ΪΛ « c JS c — ο . — CO c/3 C2 C/3 Journal of the South A frican -Speech and H earing A ssociation. V ol. 21. D ecet/tber 1974 Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2012) Audiometric Weber and Rinne Tests and Pure-Tone Thresholds 67 Pu re T on e T hr es ho ld R es ul ts (B il at er al H ea ri ng C om bi na ti on ) G ui de t o E xp ec te d R es ul ts fo r R in ne % E rr or o f W eb er R es ul ts w he n C om pa re d to T hr es ho ld R es ul ts a t: ο Pu re T on e T hr es ho ld R es ul ts (B il at er al H ea ri ng C om bi na ti on ) G ui de t o E xp ec te d R es ul ts fo r R in ne N um be r of Pa ti en ts 1 00 0 H z on ly 25 0 H z - 8 00 0 H z * (T ot al R es ul ts ) D eg re e of Si gn if ic an ce E rr or R es ul Ρ A. Bilateral Both +ve 32 3,1 6,3 No Significance Normal B. One Normal +ve 11,8 11,8 No Significance One conductive —ve 34 8,8 17,7 No Significance C. Bilateral Conductive Both - v e 15 10 10 No Significance D. One Normal +ve 0 0 No Significance One Sensori- False —ve 23 8,7 8,7 No Significance neural E. Bilateral Equal Both -i-ve 18 11,1 11,1 < 0 , 0 5 Sensori-neural F. Bilateral Unequal One -l-ve Sensori-neural and one False —ve 8 6,3 6,3 No Significance G. One Normal +ve 0 0 No Significance One Mixed False —ve 20 30 25 < 0 , 0 5 H. One Sensori- neural 35,7 35,7 < 0 , 0 5 One Mixed 14 21,4 28,6 < 0 , 0 5 1. One Sensori- neural False — ve 20 20 No Significance One Conductive - v e 5 40 40 No Significance J. One Conductive —ve 16,7 16,7 No Significance One Mixed False —ve 6 0 < 16,7 No Significance K. Bilateral Mixed 10 10 10 < 0 , 0 5 * Rinne result compared to thresholds over this range to assess agreement with total loss characteristics of ear. TABLE 11. Comparison of the agreement between the Rinne and pure tone threshold results. Tydskrif run die Suid-Afrikaanse Vereniging vir Spraak- en Gehoorheeikunde, Vol. 21, Deseniher 1974 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) 68 Alison Κ. Thompson either the patient resists believing he can hear the tone centrally (in spite of being prepared for this possibility during testing) or that the test is more sensi- tive than desired in that a slight deficit in the conductive mechanism results in lateralisation in normal ears. No definite trend was found as to the ear selected for response; neither the ear where pathology or loss was judged pre- sent nor the better functioning ear was selected. In the bilateral conductive combination (60% error) similar factors are present in that frequently the degree of loss is practically equal in both ears. A central Weber was expected, but seldom occurred. Although the Weber is considered to be primarily a test for determining pre- sence of unilateral conductive loss, results did not support this very well (23,5% error; significant at ρ < 0 , 0 1 ) . The Weber appears to be reliable in two combinations only i.e. bilateral un- equal sensori-neural hearing loss (25% error) and unilateral sensori-neural hearing loss (13% error). However, in the former case there was only a small group of eight patients and thus these results are questionable. The trend indicates that the Weber is more efficient where cochlear reserve is not equal in both ears. An inherent limitation of the Weber is that it is not possible to interpret responses obtained when a mixed loss is present, or when there is a combina- tion of sensori-neural loss in one ear and conductive loss in the other. The response obtained, from the patient may thus prove misleading. On considering the results for the Rinne, all results for similar categories i.e. normal, conductive, etc, were compared to assess whether results for any given category were comparable irrespective of the hearing characteristics of the contralateral ear. On analysis, results within each category did not differ significantly (all at ρ < 0,05) thus confirming test consistency. The Rinne is generally efficient in depicting normal hearing and conductive losses. (An arbitrary response was usually given with a conductive loss around 20 dB, thus reducing efficiency in this region). Ears with a sensori-neural loss demonstrated a significant incidence of errors (p < 0,05) in only two com- binations i.e. with a mixed loss (35,7%) and in the bilateral equal sensori- neural group (11,1%). The latter is of borderline significance only. Sensori- neural loss is therefore depicted less efficiently but results are still of value in diagnosis. Mixed losses give the least reliable results. The use of masking to prevent the false-negative response in unilateral severe sensori-neural loss has long been a problem. The general difficulties in esta- blishing effective masking levels are equally relevant here. The writer suggests that the false-negative response be accepted as it stands. In the present study, masking was not used. However, on analysis of results, the false-negative appears consistently where one would expect it to occur. The history, plus Weber and Schwabach tests, can be employed to provide further information (the present study found the Weber to be reliable in this category). There is, nevertheless, no totally satisfactory solution to ;this problem. The greatest limitation of the Weber and Rinne tests is that inconsistencies may occur in any patient's responses for a variety of psycho-acoustic, ana- . Journal of llic jioulh African Spccch and Hc Iy74 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) Audiometric Weber and Rinne Tests and Pure-Tone Thresholds 69 tomical and physical reasons. As with any test requiring a subjective response, these tests are only as efficient as the patients' preparedness and ability to judge what is presented to him. Unsophisticated patients may be more suggestible and erratic in this regard. Although findings based on the audiometric Weber and Rinne cannot be directly compared to those obtained with tuning forks, owing to the slight differences in frequency levels and presentation, trends of test efficiency can be extracted. Neither of these tests are sufficiently reliable to substitute for threshold tests. However, the findings of this study suggest that the Rinne is of value as a supplement to threshold testing. A result at variance with the threshold, levels alerts the tester to the need for closer investigation. The Weber can be used reliably to help identify a unilateral sensori-neural loss but, clearly, its general inefficiency makes it of little diagnostic value. ACKNOWLEDGEMENTS I wish to thank Dr B.L. Wolfowitz for his suggestions on presentation and Mrs J.E. Anderson for assisting with classification of results. Also, Mr G.L. Kimble and the Department of Statistics, C.H.D., Johannesburg for the statis- tical analysis; and Dr L. Faivelsohn, Medical Superintendent of Baragwanath Hospital for his permission to publish. REFERENCES 1. Allen, G.W. and Fernandez, C. (1960): The Mechanism of Bone Con- duction. Annals of Otol, Rhinol, and Laryngol, 69, 5-28. 2. Davis, H. and Silverman, S. (1970): Hearing and Deafness, 3rd edition Holt, Rinehart & Winston, New York. 3. Groen, J.J. (1962): The Value of the Weber Test. In Schuknecht, H.F. (Ed.), Otosclerosis International Symposium, Chap. 14. Little, Brown & Co., Massachusetts. 4. Harris, J.D., Haines, H.L. and Myers, C.K.,(1953): A Helmet-held Bone Conduction Vibrator. Laryngoscope, 63, 998-1007. 5. Jesberg, S. (1923): Recording of Functional Hearing Tests. Laryngo- scope, 33, 379-383. 6. Johnson, E.W. (1970): Tuning Forks to Audiometers and back again. Laryngoscope, 80, 49-68. 7. Naunton, R.F. (1963): The Measurement of Hearing by Bone Con- duction. In Jerger, J . ( E d . ) , Modern Developments in Audiology, Chap. 1. Academic Press, New York. 8. Newby, H.A. (1965): Audiology Principles and Practice, 2nd edition. Vision Press, London. 9. Nilo, E.R. (1968): The Relation of Vibrator Surface Area and Static Application Force to the Vibrator-to-head Coupling. J. of Speech and Hearing Res., 11,805-810. ivdskrif van die Suid-Afrikaanse Vereniging vir Spraak-en (Jehoorheelkunde, Vol. 21. Detember 1974 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) 70 Alison Κ. Thompson 10. Sheehy, J.L. et al. (1971): Tuning Fork Tests in Modern Otology. Arch Otolarvng., 94, 132-138. 1 1. Sonnenschein, R. (1933): Fundamental Principles of Functional Hear- ing Tests. Arch. Otolaryng., 18,599-613. 12. Tschiassny, K. (1946): Tuning Fork Tests. Annals of Otol., Rhinol., and Laryngol., 55,423-430. 13. Watson, L.A. and Tolan, T. (1949): Hearing Tests and Hearing Instru- ments. Williams and Wilkins, Baltimore. j- A U D I O M E T R Y EQUIPMENT HEARING AIDS NOISE CONTROL and and Maico Iriteracoustics Grason-Stadler Siemens Mad sen Widex Willco Eckstein Linco H I L L A R Y R E I C H E N B E R G E R I C C. L E W I S / THE NEEDLER WESTDENE HEARING AID ORGANISATION (PTY) LTD. P.O. BOX 28975, SANDR I N G H A M 2131 T E L E P H O N E : 45-7262 Journal of the Soulli African Speech anil Hearing Associaiion. I nl J/, December 19~4 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 2) Do you have an illegal racket? Government Notice R2237 of 3 0 / 1 1 / 7 3 And the onus is on you to ensure their pro- sets d o w n m a x i m u m safe noise levels in factories and workshops. It has been done to protect your workers from damage to their hearing. lection. 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