A MODIFICATION OF THE TILLMAN-OLSEN METHOD FOR OBTAINING THE SPEECH RECEPTION THRESHOLD
Frederick N. Martin and Mary Lou Stauffer University of Texas, Austin, Texas
Twenty normal-hearing subjects were tested to determine their speech reception thresholds (SRTs) using the TiUman-Olsen method and a modification of their method requiring no knowledge of the pure-tone audiogram from which to estimate the SRT. Varying amounts of attenuation were added to the line leading to the test earphone to minimize experimenter bias. The data revealed no significant differences between the two methods in either the SRTs themselves or the amount of time required to obtain them. A procedure is therefore advanced for clinicians wishing to measure SRTs without prior knowledge of pure-tone thresholds.
Since the introduction of speech audiometry to the area of hearing measurement, the speech reception threshold (SRT) has become an indispensible method of estimating hearing sensitivity for speech. T h e S R T also serves other clinical purposes. It may be used as a check on the reliability of the pure-tone audiogram, in the selection of appropriate amplification, and as a check of consistency in suspected nonorganic hearing loss (Hopkinson, 1972). Although a variety of measures have been suggested to determine the SRT, it was not until Chaiklin and Ventry's article in 1964 that precise measures and uniform procedures were devised. Recently, T i l l m a n and Olsen (1973) described a method for obtaining the S R T which appears logical, rapid, and scientific. Wilson, Morgan, and Dirks (1973) concluded from their research that this procedure is practical and recommended it for consideration as a standardized S R T method. This method, along with many previously recommended methods, involves prior estimates of hearing sensitivity, usually determined by the pure-tone average. However, there are situations in which it may be desirable or necessary to determine the S R T without prior knowledge of pure-tone average. These situations include hearing-aid evaluations, testing small children, elimination of bias in training student clinicians, and testing patients with suspected nonorganic hearing loss. T o accommodate these situations, we devised a modification of the TillmanOlsen method which can be used without a prior estimate of the degree of the 25
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
26
JOURNAL OF SPEECH A N D HEARING DISORDERS
--
XL, 1
loss. T h e purpose of the present study was to compare our proposed S R T approach with T i l l m a n and Olsen's procedure and to determine whether the two methods yield the same SRTs or if there is any difference in the time required to obtain them. PROCEDURE
Data were collected in a two-room, double-walled testing suite (Tracoustics Model RS244) that exceeded ANSI (1969) standards for audiometry. T h e basic test instrument used was a speech audiometer (Grason-Stadler 1701 with TDH-39 earphones mounted in MX-41/AR cushions). Attenuator linearity was checked periodically with a sound-level meter (Bg~K 2203) with an octave filter set (B&K 1630) and an artificial ear (Bg:K 4151). T h e pure-tone and speech circuits were calibrated to the ANSI (1969) standards and checked periodically during the performance of this study. Speech stimuli consisted of the six lists (A-F) of spondee words from CID auditory test W-1. T h e stimuli were dubbed from disc recording onto magnetic tape and played on a cassette tape deck (Wollensak 4760). An accessory attenuator (Grason-Stadler 12001293) was used to allow an amount of attenuation unknown to the experimenter to be added. Twenty normal-hearing subjects (18 temales and two males) participated in the study. Ages ranged from 20 to 23 years. Normal hearing was defined as the ability to hear tones at 15 dB H T L at seven frequencies (250, 500, 1000, 2000, 3000, 4000, and 8000 Hz). In this study, only right ears were used. Upon successful completion of screening, each subject was presented an identical, printed set of instructions to read before administration of the test. Each of these sets contained an alphabetized list of the words that would be used in the tests. Before beginning the test, each subject drew a number from a box and was instructed to set the attenuator to that number without informing the experimenter what level he had drawn. Pure-tone testing using the Carhart-Jerger (1959) descending-ascending method was performed just before administration of the Tillman-Olsen method at 500, 1000, and 2000 Hz. The pure-tone average was used to obtain an estimated SRT. Even-numbered subjects were given the Tillman-Olsen method first, and odd-numbered subjects were given our modification of the test first. T h e beginning level for the Tillman-Olsen method was determined by adding 30 dB to the pure-tone average. From this point, the Tillman-Olsen 2-dB method for obtaining the S R T was followed. For the modified method, the following procedure (Figure 1) was used. T h e subject was presented one spondee word at 50 dB H T L . If the response was correct, the level was attenuated in 10-dB steps, with one spondee presented at each level, until a word was missed. If an incorrect response was obtained, a second spondee was presented at the same level and attenuation was continued in 10-dB steps until two spondees were missed at one level. If the subject missed the first spondee presented at 50 dB H T L , the level was increased in
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
MARTIN, STAUFFER: TILLMAN-OLSEN MODIFICATION
FLOW CHART -
'
27
SPEECH RECEPTION THRESHOLD
t Jncleose
Level 20 dB
I Spondee
/Yes
9
2
@ 1 s.,,o
3
50 dB HTL
Att ItOSpondee dB .... te
~
~
10 I Spondee
i
I Spondee
L1
No
,8
Levelat
# 10 + 16 dB
I Attenuate
2 Spondees
J~os
I
2 dB
No
t Increase
Level at I 12 by 6 dB
-,x~
Ye' ' ~ , . . J
Figure 1. Flow chart for performance of the modified Tillman-Olsen speech reception threshold method.
20-dB steps until a correct response was obtained. T h e attenuation in 10-dB steps was then begun. T h e "start level" was defined as 16 dB above the level at which the subject first missed two spondees. Two spondees were presented at this level and at each 2-dB decrement. A tally was kept of the responses to determine if the subject had repeated five of the first six words correctly. If this condition was not met, 6 dB was added to the start level and the 2-dB decrements were then initiated. T h e decrements were continued until five of the last six words were missed by the subject. T h e S R T was then determined by subtracting the number of correct responses from the start level and a correction of 1 dB was added. T h e formula, basically T i l l m a n and Olsen's, is as follows: start H T L minus number of correct responses plus 1 dB. On termination of the tests, the experimenter noted the amount of attenuation that had been used. RESULTS
AND
DISCUSSION
Table 1 shows the results of a t test for the significance of the difference between two means for correlated samples on the data obtained for SRTs according to the Tillman-Olsen and our modified method. T h e differences were not
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
28
JOURNAL OF SPEECH A N D HEARING DISORDERS
--
XL, 1
TABLE 1. Means and standard deviations for speech reception thresholds (SRTs) and the number of seconds required to obtain them by the Tillman-Olsen method and the modified method described in this paper. N = 20. t critical for a significant difference at p = 0.05 2.093 (two-tailed).
Measure
SRT ( d B ) Time ( s e c )
Method
Tillman-Olsen Modified method Tillman-Olsen Modified me thod
Mean
Standard Deviation
56.70 56.75 136.25 144.25
13.51 13.43 12.86 13.30
t
r
0.10
0.98
1.78
-- 0.17
significant at the 0.05 confidence level. Moreover, correlation between the results of the two m e t h o d s was very h i g h a n d accounts for 9 6 % of the v a r i a n c e in the scores. T h i s suggests t h a t there is no difference between the two m e t h o d s w i t h respect to m e a s u r e d S R T s . Similarly, there a p p e a r to be no systematic differences between the time r e q u i r e d of the two m e t h o d s to complete the tests. A r a p i d m e t h o d for d e t e r m i n i n g the S R T is, therefore, available to clinicians wishing to p e r f o r m this test w i t h no p r i o r estimate of speech thresholds. A l o n g w i t h l e n d i n g itself to c o m p u t e r i z a t i o n , the modified S R T p r o c e d u r e p r o p o s e d here m a y prove a d v a n t a g e o u s in testing patients w i t h suspected nonorganic h e a r i n g loss, d u r i n g hearing-aid evaluations, testing small children, a n d t r a i n i n g s t u d e n t clinicians. ACKNOWLEDGMENT Requests for reprints should be sent to Frederick N. Martin, Communication Disorders, Department of Speech Communication, University of Texas, Austin, Texas 78712. REFERENCES AMERICAN NATIONAL STANDARDSINSTITUTE, American National Standard Specification ]or Audiometers, ANSI $3.6-1969. New York (1970). CARHART, R., and JERGER, J., A preferred method for the clinical determination of pure tone thresholds. J. Speech Hearing Dis., 24, 330-345 (1959). CHAIKLIN, J. B., and gENTRY, I. M., Spondee threshold measurement: A comparison of 2and 5-dB methods. J. Speech Hearing Dis., 29, 47-59 (1964). HOPKINSON,N. T., Speech reception threshold. In J. Katz (Ed.), Handbook of Clinical Audiology. Baltimore: Williams and Wilkins (1972). TILLMAN, T. W., and OLSEN,W. O., Speech audiometry. In J. Jerger (Ed.), Modern Developments in Audiology. (2nd ed.) New York: Academic (1973). WILSON, R. H., MORGAN,D. E., and DIRKS,D. D., A proposed SRT procedure and its statistical precedent. J. Speech Hearing Dis., 38, 184-191 (1973). Received May 16, 1974. Accepted June 20, 1974.
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
Frederick N. Martin and Mary Lou Stauffer University of Texas, Austin, Texas
Twenty normal-hearing subjects were tested to determine their speech reception thresholds (SRTs) using the TiUman-Olsen method and a modification of their method requiring no knowledge of the pure-tone audiogram from which to estimate the SRT. Varying amounts of attenuation were added to the line leading to the test earphone to minimize experimenter bias. The data revealed no significant differences between the two methods in either the SRTs themselves or the amount of time required to obtain them. A procedure is therefore advanced for clinicians wishing to measure SRTs without prior knowledge of pure-tone thresholds.
Since the introduction of speech audiometry to the area of hearing measurement, the speech reception threshold (SRT) has become an indispensible method of estimating hearing sensitivity for speech. T h e S R T also serves other clinical purposes. It may be used as a check on the reliability of the pure-tone audiogram, in the selection of appropriate amplification, and as a check of consistency in suspected nonorganic hearing loss (Hopkinson, 1972). Although a variety of measures have been suggested to determine the SRT, it was not until Chaiklin and Ventry's article in 1964 that precise measures and uniform procedures were devised. Recently, T i l l m a n and Olsen (1973) described a method for obtaining the S R T which appears logical, rapid, and scientific. Wilson, Morgan, and Dirks (1973) concluded from their research that this procedure is practical and recommended it for consideration as a standardized S R T method. This method, along with many previously recommended methods, involves prior estimates of hearing sensitivity, usually determined by the pure-tone average. However, there are situations in which it may be desirable or necessary to determine the S R T without prior knowledge of pure-tone average. These situations include hearing-aid evaluations, testing small children, elimination of bias in training student clinicians, and testing patients with suspected nonorganic hearing loss. T o accommodate these situations, we devised a modification of the TillmanOlsen method which can be used without a prior estimate of the degree of the 25
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
26
JOURNAL OF SPEECH A N D HEARING DISORDERS
--
XL, 1
loss. T h e purpose of the present study was to compare our proposed S R T approach with T i l l m a n and Olsen's procedure and to determine whether the two methods yield the same SRTs or if there is any difference in the time required to obtain them. PROCEDURE
Data were collected in a two-room, double-walled testing suite (Tracoustics Model RS244) that exceeded ANSI (1969) standards for audiometry. T h e basic test instrument used was a speech audiometer (Grason-Stadler 1701 with TDH-39 earphones mounted in MX-41/AR cushions). Attenuator linearity was checked periodically with a sound-level meter (Bg~K 2203) with an octave filter set (B&K 1630) and an artificial ear (Bg:K 4151). T h e pure-tone and speech circuits were calibrated to the ANSI (1969) standards and checked periodically during the performance of this study. Speech stimuli consisted of the six lists (A-F) of spondee words from CID auditory test W-1. T h e stimuli were dubbed from disc recording onto magnetic tape and played on a cassette tape deck (Wollensak 4760). An accessory attenuator (Grason-Stadler 12001293) was used to allow an amount of attenuation unknown to the experimenter to be added. Twenty normal-hearing subjects (18 temales and two males) participated in the study. Ages ranged from 20 to 23 years. Normal hearing was defined as the ability to hear tones at 15 dB H T L at seven frequencies (250, 500, 1000, 2000, 3000, 4000, and 8000 Hz). In this study, only right ears were used. Upon successful completion of screening, each subject was presented an identical, printed set of instructions to read before administration of the test. Each of these sets contained an alphabetized list of the words that would be used in the tests. Before beginning the test, each subject drew a number from a box and was instructed to set the attenuator to that number without informing the experimenter what level he had drawn. Pure-tone testing using the Carhart-Jerger (1959) descending-ascending method was performed just before administration of the Tillman-Olsen method at 500, 1000, and 2000 Hz. The pure-tone average was used to obtain an estimated SRT. Even-numbered subjects were given the Tillman-Olsen method first, and odd-numbered subjects were given our modification of the test first. T h e beginning level for the Tillman-Olsen method was determined by adding 30 dB to the pure-tone average. From this point, the Tillman-Olsen 2-dB method for obtaining the S R T was followed. For the modified method, the following procedure (Figure 1) was used. T h e subject was presented one spondee word at 50 dB H T L . If the response was correct, the level was attenuated in 10-dB steps, with one spondee presented at each level, until a word was missed. If an incorrect response was obtained, a second spondee was presented at the same level and attenuation was continued in 10-dB steps until two spondees were missed at one level. If the subject missed the first spondee presented at 50 dB H T L , the level was increased in
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
MARTIN, STAUFFER: TILLMAN-OLSEN MODIFICATION
FLOW CHART -
'
27
SPEECH RECEPTION THRESHOLD
t Jncleose
Level 20 dB
I Spondee
/Yes
9
2
@ 1 s.,,o
3
50 dB HTL
Att ItOSpondee dB .... te
~
~
10 I Spondee
i
I Spondee
L1
No
,8
Levelat
# 10 + 16 dB
I Attenuate
2 Spondees
J~os
I
2 dB
No
t Increase
Level at I 12 by 6 dB
-,x~
Ye' ' ~ , . . J
Figure 1. Flow chart for performance of the modified Tillman-Olsen speech reception threshold method.
20-dB steps until a correct response was obtained. T h e attenuation in 10-dB steps was then begun. T h e "start level" was defined as 16 dB above the level at which the subject first missed two spondees. Two spondees were presented at this level and at each 2-dB decrement. A tally was kept of the responses to determine if the subject had repeated five of the first six words correctly. If this condition was not met, 6 dB was added to the start level and the 2-dB decrements were then initiated. T h e decrements were continued until five of the last six words were missed by the subject. T h e S R T was then determined by subtracting the number of correct responses from the start level and a correction of 1 dB was added. T h e formula, basically T i l l m a n and Olsen's, is as follows: start H T L minus number of correct responses plus 1 dB. On termination of the tests, the experimenter noted the amount of attenuation that had been used. RESULTS
AND
DISCUSSION
Table 1 shows the results of a t test for the significance of the difference between two means for correlated samples on the data obtained for SRTs according to the Tillman-Olsen and our modified method. T h e differences were not
Downloaded From: https://jshd.pubs.asha.org/ by a University of Texas, Austin User on 03/27/2018 Terms of Use: https://pubs.asha.org/ss/rights_and_permissions.aspx
28
JOURNAL OF SPEECH A N D HEARING DISORDERS
--
XL, 1
TABLE 1. Means and standard deviations for speech reception thresholds (SRTs) and the number of seconds required to obtain them by the Tillman-Olsen method and the modified method described in this paper. N = 20. t critical for a significant difference at p = 0.05 2.093 (two-tailed).
Measure
SRT ( d B ) Time ( s e c )
Method
Tillman-Olsen Modified method Tillman-Olsen Modified me thod
Mean
Standard Deviation
56.70 56.75 136.25 144.25
13.51 13.43 12.86 13.30
t
r
0.10
0.98
1.78
-- 0.17
significant at the 0.05 confidence level. Moreover, correlation between the results of the two m e t h o d s was very h i g h a n d accounts for 9 6 % of the v a r i a n c e in the scores. T h i s suggests t h a t there is no difference between the two m e t h o d s w i t h respect to m e a s u r e d S R T s . Similarly, there a p p e a r to be no systematic differences between the time r e q u i r e d of the two m e t h o d s to complete the tests. A r a p i d m e t h o d for d e t e r m i n i n g the S R T is, therefore, available to clinicians wishing to p e r f o r m this test w i t h no p r i o r estimate of speech thresholds. A l o n g w i t h l e n d i n g itself to c o m p u t e r i z a t i o n , the modified S R T p r o c e d u r e p r o p o s e d here m a y prove a d v a n t a g e o u s in testing patients w i t h suspected nonorganic h e a r i n g loss, d u r i n g hearing-aid evaluations, testing small children, a n d t r a i n i n g s t u d e n t clinicians. ACKNOWLEDGMENT Requests for reprints should be sent to Frederick N. Martin, Communication Disorders, Department of Speech Communication, University of Texas, Austin, Texas 78712. REFERENCES AMERICAN NATIONAL STANDARDSINSTITUTE, American National Standard Specification ]or Audiometers, ANSI $3.6-1969. New York (1970). CARHART, R., and JERGER, J., A preferred method for the clinical determination of pure tone thresholds. J. Speech Hearing Dis., 24, 330-345 (1959). CHAIKLIN, J. B., and gENTRY, I. M., Spondee threshold measurement: A comparison of 2and 5-dB methods. J. Speech Hearing Dis., 29, 47-59 (1964). HOPKINSON,N. T., Speech reception threshold. In J. Katz (Ed.), Handbook of Clinical Audiology. Baltimore: Williams and Wilkins (1972). TILLMAN, T. W., and OLSEN,W. O., Speech audiometry. In J. Jerger (Ed.), Modern Developments in Audiology. (2nd ed.) New York: Academic (1973). WILSON, R. H., MORGAN,D. E., and DIRKS,D. D., A proposed SRT procedure and its statistical precedent. J. Speech Hearing Dis., 38, 184-191 (1973). Received May 16, 1974. Accepted June 20, 1974.
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