Identification and discrimination of vowel-consonant syllables in listeners with sensorineural hearing loss.

IDENTIFICATION AND OF VOWEL-CONSONANT IN LISTENERS WITH HEARING

DISCRIMINATION SYLLABLES SENSORINEURAL LOSS

CHARLOTTE REED

University of Pittsburgh, Pennsylvania The speech encoding ability of eight persons with sensorineural hearing loss and three persons with normal hearing was studied in identification and discrimination paradigms. In the identification task a feature analysis of transmitted information for VC s~cllables was used to study encoding ability. Transmitted information was reduce(a from normal for persons with hearing loss, indicating a loss of ability to encode consonants. In the discrimination task, coding ability was studied by measuring reaction times (RTs) for "same" and "different" decisions. The RTs for individuals with impaired hearing were found to be significantly different from those subjects with normal hearing. The trend was for faster "same" than "different" RTs among the normal subjects and faster "different" than "same" RTs among the hearing-impaired persons. The results are interpreted as indicating that the two groups of subjects used different processing modes in discriminating between pairs of phonemes. The effects of a hearing loss on the ability to understand speech have not been well defined. In clinical testing, these effects are described by the shift in threshold for spondaic words and by the ability to repeat isolated monosyllabic words. These tests provide little insight into the transformation of the speech signal that occurs as a result of the hearing loss. We were interested in investigating the effect of a sensorineural hearing loss on phonemic encoding, where encoding is defined operationally as the ability to extract and process information from the auditory waveform necessary for labeling a phoneme. Specifically, do patients with hearing loss encode speech sounds in a manner similar to that of persons with normal hearing, do they learn to recode these sounds using their residual hearing, or are they unable to perform any type of phonemic encoding? An indirect way of investigating encoding ability was suggested by results reported in a study by Bindra, Donderi, and Nishisato (1968) on reaction times (RTs) for decisions in a same-different (S-D) discrimination task. Bindra et al. interpreted the results of their study as indicating that the relative latency of "same" and "different" decisions was a function of the codability of the test signals. Codable signals, or those to which a label can be attached easily (colors in the visual modality and a click vs a pure tone in the auditory modality), yielded "same" RTs which were at least as fast as "different" 773

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RTs. On tile other hand, results for tile discrimination of noneodable signals (line lengths or pure tones) showed "different" RTs to be faster than "same" RTs. Other experimenters have reported similar results for both codable (Nickerson, 1965; Tversky, 1969; Kreuger, 1970; Bamber, 1969, 1972; Burrows, 1972) and noncodable signals (Kellogg, 1931; Bindra, Williams, and Wise, 1965; Nishisato and Wise, 1967; Nickerson, 1971). Although the evidence favoring this interpretation of results is not entirely conclusive, it still allows for a prediction of the results in a number of studies. Several investigators have measured RTs for an S-D discrimination of speech stimuli. Mclnish and Tikofsky (1969) found that the "different" RT decreased as the number of contrasting features increased from one to two, while the "same" RT was shorter than either "different" RT. Cole and Scott (1972) also found an orderly decrease in the "different" RT as the number of contrasting features increased from one to six, but did not find a significant difference between mean "same" and "different" RTs. Reed (1975) investigated "same" and "different" RTs for individual phonemic pairs and found that, in general, the "same" RT was at least as fast as the "different" RT and that the size of the difference between the two RTs was a function of the "difficulty" of the phonemic contrast. These results suggest that if a person with a sensorineural hearing loss were unable to encode the sounds of speech, then the RT pattern for decisions in an S-D discrimination would differ from that observed for subjects who encode speech in a normal manner. That is, his RTs would resemble those obtained for other noncodable signals, "different" RTs faster than "same" RTs. Durlach and Braida (1969) have described two types of memory processes which may be related to tile two patterns of "same" and "different" RTs. Although their model was generated for an intensity-resolution problem, its application has been extended here to include more general cases of auditory resolution. In one mode of processing, called the sensory-trace mode, the listener attempts to maintain the acoustical image or trace resulting from the signal presentation. In tile other processing mode, called context coding, the listener is assumed to attach a verbal label to the signal bv comparing the sensation to the general context of sounds in the experiment. A discrimination of two sounds in the sensory-trace processing mode is performed by comparing the two sensory traces. A discrimination of two sounds in the context-coding mode is performed by comparing the two verbal labels. The processing mode adopted by the listener depends on several memory-related factors, including the range of stimuli and time (or interference) effects. In general, when the memory limitations imposed by the range of stimuli are greater than those imposed by interference effects, then the sensory-trace mode is the preferred strategy. In a discrimination paradigm, if signals could be chosen from a large set of pure-tone frequencies ranging from 250 to 4000 Hz and if the intersignal interval were short (500 msec) then the task would be performed by comparing the traces resulting from the two waveforms. When time or interference effects impose a greater limitation on memorv than does the stimulus 774 lournal o[ Speech and Hearing Research


18 773-794 1975

range, then context coding is the preferred processing mode. In a task requiring the discrimination of two tones, 1000 and 1060 Hz for example, where there is interpolated activity during the intersignal interval, context coding would be the preferred mode. The listener may combine the two types of processing to optimize performance in a two-interval paradigm. When the listener is operating in the sensory-trace mode, RTs should be like those described by Bindra et al. (1968) for noncodable stimuli. When the listener is performing context coding, RTs should follow the pattern described for codable stimuli. The RTs of normal-hearing subjects in an S-D discrimination of speech sounds (Reed, 1975) indicate that normal listeners process speech as a codable signal. If a person with hearing loss, however, were unable to encode speech sounds normally, then the memory limitations imposed by the range of stimuli would be greater than those imposed by time effects (due to intersignal interval in the discrimination paradigm). The sensory-trace mode of processing would be adopted as the more optimal listening strategy and, theoretically, the RT pattern should be like that obtained for noncodable stimuli. Codability can also be examined by testing performance on phoneme identification. The model of Durlach and Braida (1969) specifies that a oneinterval identification task is performed in the context-coding mode. If the speech-encoding process is interfered with by a hearing loss, then persons with impaired hearing should have difficulty identifying phonemes. In addition, Wang and Bilger (1973) have shown that a high percentage of transmitted information for consonant identification in normal listeners can be explained in terms of acoustical and phonological features. Tile extent to which these features are used by a person with impaired hearing may be related to the degree to which he is encoding speech in a "normal" fashion. The purpose of the research described here was to examine the ability of persons with sensorineural hearing loss to encode speech. Encoding ability was examined by comparing performance and RTs in an S-D discrimination task to that of normal subjects tested under similar experimental conditions (Reed, in press) and by testing performance in consonant identification. METHOD Discrimination Experiment The selection of phonemes for the discrimination experiment was facilitated by the availability of confusion matrices for vowel-consonant (VC) syllable identification collected by Bilger, Wang, and Jesteadt (1972) for 22 listeners with impaired hearing. The difficulty of each phoneme was assessed by tabulating the frequency with which it was missed by each listener. Five phonemes representing a range of difficulty were chosen to serve as standards for the discrimination experiment. The standards, in order of decreasing difficulty, w e r e / ~ / , / d 3 / , / 3 / , / , q / , a n d / t / . REED: Vowel-Consonant Syllables 775


Four phonemes for comparison with each standard were selected on the basis of confusion with the standard (as determined from the confusion matrices) and of allowing for a range of feature differences. The resulting 20 "different" comparisons are given in Table 1, with the number of features TArtLY. 1. A list of the 20 phonemic comparisons (four comparisons with each of five standard,s) and the feature differences (Wickelgren, 1966) between each pair. Feature Differences (Wickelgren, 1966) Number Features

Phonemic P a i r

/6-v/ /~5-d/ /6-0/ /6-9/ /d3-tJ'/ /d3-g/ /d3-d/ /d3-f/ /3-z/ /5-J'/ /3-g/ /5-d3/ /g-d/ /9-k/ /g-rj/ /g-0/ /t-s/ /t-d/ /t-v/ ~t-z~ .

.

.

.

1 1 1 4 1 1 2 5 1 1 2 1 3 1 1 5 2 1 3 3 .

.

Place Openness Voicing Openness,Place (3) Voicing Place Place (2) Voicing, Openness, Place (3) Place Voicing Openness,Place Openness Place (3) Voicing Nasality Voicing, Openness, Place (3) Openness,Place Voicing Voicing, Openness, Place Voicing, Openness, Place

.

(Wickelgren, 1966) by which each pair contrasts. Each degree of difference along the five-value place feature has been counted as a unit difference. The dependence of a discrimination task on short-term memory prompted the use of the Wickelgren feature system, since it was derived from confusions made in a short-term memory task. Analog recordings of VC syllables (with the vowel / a / ) by a male talker were digitized using a 10-bit analog-to-digital (A-D) converter with a sampling rate of 10 k Hz. The digitized version of each syllable was then passed through a D-A converter and a voltage-time plot was made. Durations of the syllables were determined through visual inspection of these plots and each syllable was trimmed to the length of the shortest syllable (335 msec). The trimming was done to ensure a uniform duration of each syllable for the discrimination task. Each of the trimmed syllables was judged by two experienced listeners to be as intelligible as its untrimmed counterpart. Syllable pairs were recorded under computer control by passing the digital values of the syllables through a D-A converter onto an Ampex PR-10 tape 776 1ournal of Speech and Hearing Research


18 773-794 1975

recorder, recording at a speed of 7.5 in./sec. The syllables were recorded with an intersignal interval of 750 msec and with 6 sec between pairs of syllables. At playback, the output of tile tape recorder was passed through an attenuator into a calibrated TDH-49 earphone in a sound-treated room (IAC 401A). The level of tile syllables was set at 50 dB above the SRT (in dB HL), with reference to a 1 k Hz calibration tone. Twenty-five lists were recorded, each consisting of 80 randomized phoneme pairs. Each list contained an equal number of "same" and "different" trials. The 40 "different" trials were two presentations, one in each order, of the 20 "different" comparisons listed in Table 1. The "same" comparisons were two each with the standard ( / ~ / , / d s / , / 5 / , / 9 / , a n d / t / ) and comparison phonemes ( / k / , /d/, /f/, /s/, /v/, /zl, Itfl, /f/, /0/, and /13/) . The remaining"same" comparisons necessary to balance the list were drawn from the phonemes/m/, /n/, /p/, a n d / b / , which were neither standards nor comparisons. A PDP-15 computer was used to run the experiment and to store responses and RTs for later analysis. A series of coincidence indicators paced the experiment, beginning with a 500-msec warning light. A light labeled Observe marked the presentation of the first syllable of a pair, which was separated by 750 msec from tile second syllable. The second syllable of a pair was coincident with the lighting of a button labeled Answer. The answer light remained on, for up to 4 sec, until tile subject responded by pressing one of two buttons labeled SAME and DIFF. Correct answer feedback was provided. Reaction time was measured to the nearest msec, timing out the interval from the onset of the second syllable to the depression of a response button. For five of the subjects the left-to-right positioning of the response buttons was SAME-DIFF, and this order was reversed for the other six subjects. The subjects were instructed to answer as quickly as possible, using the index finger of their right hand. Contralateral masking was used in the nontest ear when there was a difference of 15 dB or more in the SRT for the two ears. Subjects listened to each of the 25 lists twice. Thus, 100 observations were collected on each phonemic comparison. This is the same number of trials used by Reed (1975) in a studv of normal listeners, to which the present data will be compared.

Identification Experiment The stimuli for the identification task were 48 VC nonsense syllables which consisted of 16 consonants (Ip/, It~, Ikl, Ibl, Idl, 191, If/, I01, Is/, If/, Iv/, /~/, /z/, /3/, /tf/, a n d / d s / ) paired with the vowels/i/, /a/, a n d / u / . These consonants included all those which were used in the discrimination task except for the phoneme /13/. The syllables were recorded by a male talker and stored on a Cognitronics Speechmaker. The speechmaker was interfaced to a paper tape reader which was programmed to control presentation of the syllables and to record responses. (Detailed information about the operation of this system is provided in Wang and Bilger, 1973.) REED: Vowel-Consonant Syllables 777


Subjects were seated in a sound-treated booth in front of a response console that contained a 4 • 4 array of buttons labeled with each of 16 consonants. Each trial consisted of a 500-msec warning light followed by a 511-msec observe interval, during which a syllable was presented. When a button labeled Answer was lighted, the subject responded by pressing the button corresponding to the sound he heard. Correct answer feedback was provided. Subjects listened to 10 randomized lists of 96 items each. Each list was composed of two presentations of each of the 48 syllables. Subjects listened monaurally through a calibrated TDH-49 earphone. Contralateral masking was used under the same conditions as those described for the discrimination experiment. The speech was presented at a level of 50 dB above the SRT, calibrated re a 1 k Hz pure tone.

Subiects The subjects were 11 persons chosen on the basis of referral for audiological testing by their physicians. The audiological test results for these persons are presented in Table 2. Subjects 1 and 2 were normal controls. The normal ear

TABLE 2. Summary of pertinent results from audiological testing for the 11 outpatients.

Patient Number

SRT (dB HL)

W-22 Score(~)

Shape of Audiogram

Etiology of Loss

1 2 3 4 (RE) 4 (LE) 5

0 10 50 8 60 42

100 100 64 96 54 84

Normal Normal Flat Normal Flat Flat

6

38

72

7 8 9 10 11

66 24 38 40 48

48 30 52 20 48

Poss Dx: Meniere's Unknown Sudden onset, noise history Poss Dx: multiple sclerosis Poss Dx: Meniere's Unknown Congenital Noise history Unknown-retrocochlear findings

Flat Flat ~ J

Age

Duration of Loss (Years)

50 24 45 46 46 42

1 9. 0.5

41

3

33 49 30 51 49

19 39 30 4 3

of Subject 4 was tested in addition to his impaired ear. The patients with sensorineural hearing loss were chosen on the basis of an elevated SRT and a reduced score on the W-22 test. Each subject was tested on three different days (with the exceptions of Subiect 1 who completed only the first day and Subject 4 who required six days for the testing of both ears). Subiects were paid an honorarium plus travel expenses for each day of participation in the experiment. 778 1ournaI of Speech and Hearing Research


18 773-794

1975

RESULTS

IdentiIication Experiment Confusion matrices for the 16 consonants were formed for each subject from the responses in the identification task. The percent correct was calculated for the matrix as was an information metric that was the amount of transmitted information (TI) for the matrix. Maximum TI for the 16 • 16 stimulusresponse matrix was 4.00 bits, because each syllable was presented equally often. Confusion matrices were analyzed further by determining the contributions of various phonological and articulatory features to TI, using a sequential information analysis described by Wang and Bilger (1973). This procedure calculates the TI for a confusion matrix and determines what proportion of the TI is accounted for by a given set of features. Since feature sets are usually highly redundant, the contributions of individual featnres are assessed sequentially. In each iteration one feature is extracted. In the first iteration, the feature extracted is the one with the highest percentage of feature information transmitted. Ill later iterations previously extracted features are held constant and these effects partialed out of remaining features. The feature extracted in any iteration is the one with the highest percentage of (conditional) feature information transmitted. Tlle analysis terminates if remaining features do not contribute significantly to TI. The order in which features are extracted indicates the perceptual importance of the feature. A more detailed description of the analysis may be found in Wang and Bilger (1973). The features included ill this analysis were the Chomsky-Halle (1968) features of high/anterior, back, coronal, and strident; the Miller-Nicely (1955) features of frication, duration, and place; the Wickelgren (1,966) feature of openness; the Singh (1968) feature of sibilance; and the feature of voicing, which is common to all systems. A summary of the results of the sequential information analysis is given in Table 3 for selected subjects. Typical data for normal subjects are provided in the first row of Table 3. For the sake of clarity, the results of four selected subjects (Subjects 3, 5, 8, and 11) will be presented in the text. (Individual data from the identification experiment for the remaining subjects are provided in Appendix A.) Subject 3 was diagnosed as having Meniere's Disease, but his data throughout the experiment were typical of those obtained on a normal ear, possibly because the disease was in a state of remission at the time. Data for normal subjects, given in the first row of Table 3, show that these subjects scored 92.6% correct on the identification task and transmitted 3.579 bits of information. In the sequential information analysis, the feature of sibilance had the highest percent of feature TI and was thus the first feature extracted in the analysis. With sibilance held constant, the high/anterior feature had the highest percent feature TI and was extracted second in the analysis. With the first two features extracted held constant, frication had the highest percent feature TI and was the third feature extracted. With the first three features extracted held constant, voicing had the highest percentage of REED: Vowel-Consonant Syllables 779


I I ! 1 1

I1~?1

g~e ~,.z:l _m

~.~ ~

~S8s~ ~

I

I

I

~~

9-.~ t3,~ ,-.~ |C,,l

r162

~,~ ~'~ __;1~ 0 0

r t~

~.~ "~ 780

~

I..N 0

Z

Journal of Speech and Hearing Research


18

773-794

1975

feature TI and was extracted in the fourth iteration of the analysis. With the first four extracted features held constant, the duration and open features were nondistinguishable and had the highest percent feature TI. With the first five features extracted from the analysis held constant, the place and coronal features (which were nondistinguishable at this stage of the analysis) had the highest percent feature TI. The TI added across these six features was 3.502 bits, which is 97.8~ of the total TI given in Column 3. Subject 3 had 81.5~ correct and 3.262 bits of TI. The order in which the features were extracted from the sequential information analysis was: duration, sibilance, open, high/anterior, voice, and place/coronal. The TI for these features accounted for 94.1~ of the TI. These results are similar to the normal data. Subiects 5, 8, and 11 had reduced percent correct, TI, and percent TI explained by the feature analysis. (It should be noted that percent explainable TI may depend on TI so that the percentage of explainable TI decreases as TI decreases.) Subiect 5 had 53~ correct with 2.085 bits of TI. The features extracted from the analysis were sibilance, open, voice, back, coronal, and place/high/anterior, accounting for 82.6~ of the TI. Subiect 8 had 28.2~ correct and 1.480 bits of TI. Five features, accounting for 69.7~ of the TI, were extracted from the analysis. Voice and frication were the two most important features, followed by openness, back, and place. Subiect 11 scored 11.8~; correct, with 0.470 bits of TI. Voicing was the most important feature for this subiect, followed by sibilance, place, and open. The sum of the feature TI for these four features was 48.2~ of the TI.

Discrimination Experiment Performance. For a signal detection analysis of each of the 20 phonemic comparisons, the pertinent trials were the "different" trials with a given comparison and the "same" trials with the two phonemes involved in the comparison. A 2 X 2 matrix with dimensions of "same" and "different" was constructed for each of the 20 comparisons, with a total N -- 300 for each subiect. Cell entries in the matrix were the numbers of each type of response. Of the 300 trials, 1130were "different" trials with a given comparison and the remaining 200 trials were 100 "same" trials with each of the two phonemes that made up the comparison. For the comparison of /g-k/, for example, the "same" trials were 100 trials each for /g-g/ and /k-k/ and the "different" trials were 50 each for /g-k/ a n d / k - g / . Although the grouping of trials in these matrices results in a 2:1 ratio of "same" to "different" trials, this ratio was 1:1 for data collection. Three measures were calculated for each of these matrices. One was P(SIs) (where the upper case letter denotes the response and the lower case letter the stimulus), probability of a correct "same" response (hit rate). Another measure was P(SId), or probability of responding "same" to a different trial (false-alarm rate). The third measure was a sensitivity index, d p. The hit rates for each phoneme for individual subjects are presented in Table 4. For most of the subiects , the hit rate did not vary greatly from phoneme to REED: Vowel-Consonant Syllables 781


TABLE 4. P( Sis ), or hit rate, for each of the 15 phonemes for individual subjects. Phoneme

1

2

3

/5/ /ds/ /5/ /9/ /t/ /k/

0.96 0.97 0.99 1.00 0.99 1.00 0.95 1.00 1.00 0.99 0.99 1.00 0.99 0.98 1.00

1.00 1.00 1.00 0.97 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.97 1.00

0.97 1.00 1.00 1.00 0.99 1.00 0.94 0.99 0.99 1.00 1.00 0.99 1.00 ].00 1.00

/d/ [f[

/0/ /s/ /[/ /v/ /z/ /13/ /tJ'/

Patient Number 4 (RE) 4 (LE) 5 6 7

0.99 0.98 0.99 0.97 0.99 1.00 0.97 1.00 0.98 1.00 0.99 1.00 1.00 ].00 0.99

0.99 0.99 1.00 0.93 1.00 1.00 0.96 0.98 0.98 1.00 0.99 0.97 0.92 0.99 1.00

0.99 0.96 0.97 0.98 1.00 1.00 0.99 0.97 1.00 1.00 0.98 1.00 0.99 1.00 1.00

0.98 0.97 0.98 0.93 0.97 0.97 0.95 0.97 0.99 1.00 0.98 0.91 1.00 0.99 1.00

0.97 0.93 1.00 0.94 0.96 0.98 0.84 0.97 0.92 0.97 1.00 0.89 0.86 0.95 0.98

8

9

0.99 0.99 0.99 0.97 0.99 0.98 0.98 0.98 0.96 0.97 0.97 0.98 0.99 1.00 1.00

0.97 0.94 0.94 0.82 1.OO 0.97 0.98 0.97 0.95 0.99 0.98 0.97 0.96 0.99 0.98

10

11

0.89 0.77 0.97 0.89 0.84 0.95 0.78 0.86 0.75 0.92 0.86 0.81 0.79 0.99 0.88

0.98 0.97 0.94 0.92 0.99 0.98 0.97 0.98 0.97 1.00 0.96 0.90 0.92 0.93 0.99

phoneme; however, Subject 10 had hit rates which ranged from 0.75 to 0.99 and Subject 7 had hit rates ranging from 0.84 to 1.00. Because hit rates for these two subjects did deviate, comparison of performance among subjects was made on the basis of d' values. To compare the performance of patients to that of the normal subjects in the study of Reed (1975), d' values averaged across the four normal subjects were converted to maximum percent correct. Confidence intervals at the 95~ level were established using an arcsin transformation and Bernoulli's Law (Walker and Lev, 1953, 423 passim), and the lower bound of the confidence interval was reconverted to a value of d'. The lower bound of the confidence interval for d' is given in the final column of Table 5. False-alarm rate and d' for each of the 20 comparisons are presented for the four selected subjects in Table 5. (The d' values and false-alarm rates for the remaining subjects are provided in Appendix B.) A simple binomial test shows that in comparing subjects to these 20 confidence intervals we would expect only 5~ of a normal population to fall outside the interval on more than two occasions. The subjects whose d' values fell outside the normal confidence intervals on zero, one, or two occasions (Subjects 1, 2, 3, 4R, 4L, and 5) were exhibiting chance variations in normal behavior. The six subjects whose d' values were below the lower cutoff on more than two occasions may be considered abnormal in discriminatory ability. These subjects were Subjects 6 and 8, who had three d' values below the confidence intervals; Subject 7, who had five d' values below the confidence intervals; Subjects 10 and 11, who had 10 deviant d' values; and Subject 9, who had 11 deviant d' values. Reaction Times. Mean RTs were calculated for individual phonemic comparisons from the 2 • 2 matrices described in the preceding section. The mean correct "different" and "same" RTs (in msec) for each comparison and the difference, D - S, between these two RTs are presented in Table 6 for the 782 Journal of Speech and Hearing Research


18 773-794 1975

TABLE 5. False-alarm ( F A ) rates and d' values for the 20 comparisons for four selected subjects. Given the input characteristics of the matrices from which these d' values were derived (200 same trials and 100 different trials), the largest possible d' (for one error of each type) is 4.90. This number has been used as an approximation of d' when either P ( S I d ) or P ( D I s ) is 0. Asterisks denote cases where the d' fell below the 95% normal confidence interval. The lower bound of the 95% confidence based on data averaged across four normal subjects (Reed, 1975) for each comparison is given in the final column.

Phonemic Comparison

3

5

Subiect 8

11

Lower Bound of 95% Con~dence Interval

0.11 2.92

0.82 1.42"

0.88 1.00"

0.90 0.67*

2.35

0.00 4.90

0.00 4.90

0.00 4.90

0.0.0 4.90

2.50

0.00 4.90

0.01 4.90

0.03 4.02

0.13 2.67

2.22

FA d' /d3-tJ'/ FA d'

0.00 4.90

0.00 4.90

0.03 3.91

0.41 1.87"

3.06

0.09 4.90

0.02 4.11

0.00 4.90

0.27 2.67*

2.68

FA d' /d3-d/ FA d' /d3-f/ FA d'

0.01 4.90

0.00 4.90

0.08 3.44

0.02 3.64

3.21

0.00 4.90

0.00 4.90

0.00 4.90

0.02 3.93

3.76

0.00 4.90

0.00 4.90

0.00 4.90

0.11 3.18

2.23

0.00 4.90

0.00 4.90

0.01 4.36

0.03 3.52

2.95

0.00 4.90

0.01 4.13

0.09 3.64

0.18 2.61"

3.42

0.01 4.90

0.01 4.28

0.05 3.67

0.09 2.80*

2.95

0.00 4.90

0.21 2.86

0.69 1.81"

0.76 0.77*

2.31

0.00 4.90

0.00 4.90

0.00 4.90

0.01 3.96

2.90

0.07 3.35

0.11 3.39

0.07 3.42

0.60 1.35"

3.10

FA dr

0.00 4.90

0.00 4.90

0.05 4.03

0.32 1.91"

2.98

FA d'

0.00

0.00

4.90

4.90

0.00 4.90

0.02 3.65

2.98

I~-dl FA d'

/5-o/ FA dt

IS-vl FA d'

/5-g/

/d3-g/

/3-I/ FA d'

/3-d3/ FA d'

/s-g/ FA d'

~s-z~ FA d'

/g-W FA dr /g-d/ FA d'

/g-o/ /g-o/

-

REED: Vowel-Consonant Syllables


783

Table 5 (Cont.) Phonemic Comparison /t-d/ FA d'

3

5

Subiect 8

11

Lower Bound of 95~ Confidence Interval

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

3.32

0.00 4.90

0.00 4.90

0.45 2.16"

0.94 1.03"

2.89

0.00 4.90

0.00 4.90

0.02 4.21

0.12 2.77*

3.44

0.00 4.90

0.00 4.90

0.00 4.90

0.02 3.74

3.21

/t-s/ FA dt

/t-v/ FA d'

/t-z/ FA d'

TABLE 6. Correct "different" ( D ) and "same" (S) RTs in msec and their difference, D -- S, for each of the 20 phonemic comparisons for four selected subjects. For each comparison, the "same" RT is the mean of 200 observations and the "different" RT is the mean of 100 observations. Asterisks denote cases where the D - S values fell below those defined by the 95~ normal confidence intervals given in Table 7. The average D -- S values across comparisons contrasting an equal number of features do not include values for comparisons where P(S]d) exceeded 0.60.

Subject Contrasts

3

5

8

11

1092.0 987.0 105.0

1307.0 1022.0 285.0

1510.0 1085.0 425.0

1296.0 1158.0 138.0

987.0 971.0 16.0

965.0 1052.0 --87.0*

1074.0 1168.0 --94.0*

1071.0 1187.0 --116.0"

1020.0 976.0 44.0*

1081.0 1056.0 25.0*

1126.0 1116.0 10.0"

1214.0 1270.0 --56.0*

1010.0 963.0 47.0

997.0 997.0 0.0"

1004.0 1189.0 -185.0"

1013.0 1186.0 - 173.0"

D S D -- S

979.0 973.0 6.0

961.0 1035.0 -74.0*

1153.0 1169.0 - 16.0"

1245.0 1232.0 13.0

/ds-tl/ D S D - S

1035.0 877.0 158.0

985.0 971.0 14.0

1050.0 1101.0 -51.0"

1268.0 1126.0 142.0

1-Feature

IS-d~ D S D-- S

/s-0/ D S D-

S

/6-W D S D -- S

/g-k/ D S D-- S

/g-0/

784

Journal of Speech and Hearing Research


18

773-794

1975

Table 6 (Cont.) Subject Contrasts

5

8

11

933.0 972.0 - 39.0

955.0 1023.0 - 68.0*

1128.0 1195.0 - 67.0*

1012.0 1206.0 - 194.0"

D S D -- S

969.0 905.0 64.0

984.0 1010.0 --26.0*

1074.0 1164.0 --90.0*

1134.0 1175.0 --41.0"

/3-d3/ D S D - S

944.0 977.0 - 33.0

990.0 1002.0 - 12.0

1125.0 1150.0 - 25.0

1152.0 1214.0 - 62.0

980.0 891.0 89.0*

1165.0 1007.0 158.0

1505.0 1142.0 363.0

1599.0 1247.0 352.0

D S D -- S

977.0 969.0 8.0

973.0 1002.0 --29.0*

986.0 1115.0 -- 129.0"

993.0 1160.0 -- 167.0"

Average D -- S

42.3

--9.9

--71.9

--52.0

944.0 977.0 -- 33.0

971.0 1033.0 -- 62.0

1124.0 1211.0 -- 87.0"

1090.0 1264.0 -- 174.0"

/d3-g/ D S D - S

3

/3-f/

/3-z/ D S D -- S

/t-d/

2-Feature

13-gl D S D -- S

/t-s/ D S D -- S

977.0 902.0 75.0

980.0 993.0 -- 13.0"

1284.0 1133.0 151.0

1694.0 1179.0 515.0

/d3-d/ D S D -- S

934.0 947.0 - 13.0

956.0 1064.0 -- 108.0"

994.0 1135.0 -- 141.0"

1411.0 1137.0 -- 125.0"

Average D -- S

9.7

-- 61.0

--25.7

-- 149.5

1107.0 1021.0 86.0

1132.0 1040.0 92.0

1205.0 1173.0 32.0

1411.0 1186.0 225.0

937.0 958.0 --21.0

970.0 1037.0 --t57.0"

1063.0 1146.0 --83.0*

1114.0 1272.0 -- 158.0"

3-Feature

/g-d/ D S D -- S

/t-v/ D S D -- S

REED:

Vowel-Consonant Syllables


785

Table 6 (Cont.) Subfect Contrasts

3

5

8

11

/t-z/ D S D - S

958.0 908.0 50.0

951.0 991.0 -40.0

997.0 1107.0 - 110.0"

1024.0 1212.0 -- 188.0"

Average D -- S

38.3

- 5.0

- 53.7

-- 70.3

1007.0 1012.0

1114.0 1145.0 -31.0

1312.0 1266.0

-5.0

1078.0 1037.0 41.0

/g -0/ D S D -- S

998.0 1005.0 -- 7.0

1004.0 1069.0 -- 65.0*

1071.0 1257.0 -- 186.0"

1014.0 1215.0 -- 201.0"

/ds-f/ D S D -- S

951.0 926.0 25.0

979.0 1036.0 --57.0*

1053.0 1207.0 -- 154.0"

1077.0 1193.0 -- 116.0"

Average D -- S

4.3

- 27.0

- 123.7

- 90.3

4- and 5-Feature /d-g/ D S D -

S

46.0

selected subjects. The phonemic comparisons are arranged according to the n u m b e r of contrasting Wickelgren (1966) features. To compare the relative latency of "different" and "same" RTs to that of the normal subjects studied in Reed (1975), confidence intervals at the 95% level were constructed from the mean D -- S values across the four normal subiects. The mean D -- S values across the normal subjects for each comparison and the lower bound of the 95% confidence interval are given in Table 7. The D -- S values of the subjects listed in Table 6 that fell below these lower limits are marked b y an asterisk. These marked values indicate that the "different" RT was faster relative to the "same" R T than it was for normal subiects. ( R T data for the remaining subjects are provided in Appendix C.) On the basis of a simple binomial test, it can be concluded that subiects from a normal population would be expected to fall outside the confidence intervals on more than two occasions only 5% of the time. Subiects with two or fewer values below the confidence intervals, therefore, can be considered normal, while those with more than two deviant values can be considered abnormal. The subiects whose D -- S values fell below the normal confidence intervals on zero, one, or two occasions were Subiects 1, 2, and 3. The remaining eight subjects, all hearing-impaired listeners, fell outside the confidence intervals on more than two occasions. Subiect 10 had six D - S values below the normal confidence intervals, Subiect 9 had nine deviant values, 786 Journal o[ Speech and Hearing Research


18 773-794

1975

TABLE 7. Confidence intervals (t = 3 dr) at the 95% level for normal mean values of D -- S, obtained from averaging the data of four normal subjects (Reed, 1975).

Comparison /B-v/ fiS-d/ /6-0/ /b-g/ /ds-t~/ /ds-g/ /ds-d/ /d3-f/ /3-z/ /5-f/ /5-9/ /5-d5/ /g-d/ /g-k/ /9-1]/

/g-0/ /t-s/ /t-d/ /t-v/ /t-z/

Lower Limit o[ Confidence Interval

X

55 36 4 - 124 3 -62 - 36 - 50 97 -- 18 - 65 -74 - 17 13 -- 8 -53 54 -25 -24 - 48

149.0 129.5 97.8 - 29.5 51.8 -- 13.5 12.0 - 1.5 137.0 22.2 - 24.5 --34.0 34.2 63.2 42.2 -3.0 93.5 14.2 15.5 - 8.2

Subject 4 h a d 10 deviant values, Subjects 5, 7, and 11 each h a d 12 deviant values, and Subjects 6 and 8 had 14 values apiece that were below the normal confidence intervals. In some cases, D - S values for patients were very large, as in t h e / 5 - z / a n d /~-d/ comparisons for Subject 8. These cases were always comparisons for which the false-alarm rates were high, 0.60 or above. Because of the high false-alarm rates, the number of trials averaged into the mean correct "different" RT was greatly reduced, making the mean a less stable estimate. For this reason, when average D -- S values were computed across comparisons contrasting an equal n u m b e r of features (Table 6), those comparisons for which the false-alarm rate exceeded 0.60 were not included. These average D - S values were greater than zero for Subject 3, indicating generally faster "same" than "different" RTs. The size of the difference between "'different" and "same" RTs decreased as the number of contrasting features increased for Subject 3, a finding that was also observed in the normal data. In most cases the average D - S values for the hearing-impaired subjects were negative values, indicating faster "different" than "same" RTs, on the average, for any n u m b e r of contrasting features. DISCUSSION The ability of persons with sensorineural hearing loss to identify phonemes from a set of 16 VCs was found to be reduced from normal. Not only was REED: Vowel-Consonant Syllables 787


there a reduction in transmitted information for these subjects, but also a different weighting of features was obtained in the feature analysis. The importance of various features was found to be related to the audiometric configuration. Subjects 3, 4, 5, and 6, for whom similar results were obtained in the feature analysis, all had fiat sensorineural hearing losses. The features extracted from the sequential information analyses for these subjects included sibilance, duration, open, voicing, high/anterior, and place. The ordering of features differed from that for normal subjects in that duration and open were relatively more important features for these hearing-impaired subjects while high/anterior was a less important feature. Subject 9, who had a fiat loss for frequencies below 1000 Hz with improved hearing above 1000 Hz, had results similar to those of the persons with fiat sensorineural losses. The ability of persons with fiat sensorineural loss to identify sibilant sounds has been noted by Owens, Benedict, and Schubert (1972). Walden and Montgomery (1975), in analyzing similarity judgments for phonemes made by persons with hearing loss, have found sibilancy to be an important dimension for listeners with fiat sensorineural loss. The results of the feature analysis used here are thus supported by results obtained by other experimenters. Subjects 8, 10, and 11 had high-frequency losses above 500 Hz. The slope of the hearing loss in the octave between 500 and 1000 Hz was 50 dB/octave for Subjects 10 and 11 and 70 dB/octave for Subject 8. The results of the feature analyses for these subjects showed voicing and frication to be important features. Sibilancy and high/anterior, which received a high weighting in the analyses for normal listeners, were not important features for the listeners with steeply sloping losses above 500 Hz. The results of the discrimination experiment indicate that the processing strategy used in discriminating phonemes was different for hearing-impaired and normal listeners. For the subjects with normal hearing (Subjects 1 and 2) "same" RTs were generally faster than "different" RTs. The RTs of Subject 3 were like those obtained for the two normal subjects. When the relative speed of the "same" and "different" RTs for individual phonemic comparisons for these subjects was compared to confidence intervals established from a normative study (Reed, 1975), it was not found to be significantly different from normal. For each of the persons with sensorineura] hearing loss however, the relative speed of the "same" and "different" RTs was different from normal, as evidenced by a significant number of D - S values below the normal confidence intervals for individual phonemic comparisons. The trend among the hearing-impaired listeners was for "different" RTs to be faster than "same" RTs. There were differences among the hearing-impaired subjects in the degree to which this trend was observed, with the number of comparisons for which D - S values were below normal ranging from six out of 20 for Subject 10, to 14 out of 20 for Subjects 6 and 8. One interpretation of these data is in terms of the Bindra et al. (1968) hypothesis and the Durlach-Braida (1969) memory model. The faster "same" than "different" RTs for the normal subjects suggest that they processed pho788 1ournal of Speech and Hearing Research


18 773-794 1975

nemes as codable stimuli. The general trend among the hearing-impaired listeners for faster "different" RTs relative to "same" RTs than was observed for normal subjects suggests that these listeners processed phonemes for discrimination as noncodable signals. In terms of the Durlach and Braida (1968) model, the RTs for the same-different discrimination suggest that listeners with normal hearing discriminated speech sounds in the context-coding mode. The RTs for listeners with sensorineural hearing loss, however, indicate that these subjects were using a sensory-trace processing strategy, or a combination of the two modes. The sensory-trace mode is the preferred strategy when effects due to stimulus range impose a greater limitation on memory than do time or interference effects. In cases where the hearing-impaired subjects were unable to encode speech sounds efficiently, the stimulus range imposed the greater limitation on memory, forcing these subjects into the sensory-trace mode. The results for Subject 10 indicate that he, in particular, may have used a combination of the two modes. For the normal-hearing subjects, who were able to encode the speech sounds easily, the stimulus range presented no problem. These subjects thus processed the stimuli in the context-coding mode. The pattern of RTs of each of the hearing-impaired listeners suggests that these subjects were using, to some degree, a sensory-trace comparison in discriminating speech sounds. There were, however, differences in the ability to discriminate VCs among the hearing-impaired listeners. Subjects 4 and 5 were able to discriminate as well as the normal subjects (on the basis of fewer than three d' values below the normal confidence intervals) while the remaining subjects performed significantly below normal on the discrimination task. The differences in performance on the discrimination task among the sample of persons with sensorineural loss studied here indicates that some subjects were able to process auditory traces accurately while others were not. Both Subjects 4 and 5 had experienced their losses for relatively short periods of time. Differences in the ability to discriminate may reflect on the overall severity of the hearing loss. While Subjects 4 and 5 had normal discriminatory ability, their ability to identify phonemes in the one-interval recognition task was below normal. Subject 11 performed barely above chance on the recognition task (12~ correct in a 16-alternative forced-choice procedure), while her overall performance o n the discrimination task was well above chance with a d' of 2.38. This evidence lends support to the conclusion that different modes of processing were used by the hearing-impaired subjects in discriminating and identifying phonemes. While the one-interval recognition task requires encoding of sounds, the discrimination task can be performed either by encoding or by comparing sensory traces (Durlach and Braida, 1969). The results of the identification experiment indicate that the hearing-impaired subjects used traditional features in a less efficient manner than did normal listeners. The RTs in the discrimination experiment, however, may be interpreted as indicating that the subjects with impaired hearing chose to discriminate phonemes in a nonverbal mode or through a combination of verbal and nonverbal processing. It should be Rr~.D: Vowel-Consonant Syllables 789


pointed out that the ability to discriminate between two sounds does not necessacily imply the ability to identify each of the two sounds. The processing demands on the auditory system are different for recognition and discrimination, and a person with hearing loss may be able to discriminate two sounds without being able to extract information from the auditory waveform necessary for labeling the phonemes. ACKNOWLEDGMENT This research was supported by a grant from NINDS (NS 12501) and by an SRS Training Grant (44-P-15072). The paper is derived from a doctoral dissertation presented to the University of Pittsburgh. The author wisheg to thank the following persons who offered valuable criticism on earlier versions of the paper: R. Bilger, L. Braida, R. Cole, A. Holland, W. Jesteadt, and M. Wang. REFERENCES

BAMBER, D., Reaction times and error rates for "same"-"different" judgments of multidimensional stimuli. Percept. Psychophys., 6, 169-174 (1969). B~MBEn, D., Reaction times and error rates for iudging nominal identity of letter strings. Percept. Psychophys., 12, 321-326 (1972). BmcEn, R. C., WANC, M. D., and JESTEADT, W., Consonant confusions in patients with hearing loss. (abstract) 1. acoust. Soc. Am., 52, 113 ( 1972 ). BINDRA, D., DONDE~, D. C., and NISHISATO, S., Decision latencies of "same" and "different" judgments. Percept. Psychophys., 3, 121-130 (1968). BINDaA, D., WmtaA~S, J. A., and WISE, J. S., Judgments of sameness and difference: Experiments on decision time. Science, 150, 625-627 (1965). Btranows, D., Modality effects in retrieval of information from short term memory. Percept. Psychophys., 11, 365-372 (1972). CHOMSKY, N., and HALI_~, M., The Sound Pattern of English. New York: Harper and Row (1968). COL~, R. A., and SCOTT, B., Distinctive feature control of decision time: Same-different judgments of simultaneously heard phonemes. Percept. Psychophys., 12, 91-94 (1972). DURLACH, N. I., and BnAIDA, L. D., Intensity perception. I. Preliminary theory of intensity resolution. ]. acoust. Soc Am., 46, 372-383 (1969). KELLOGG,W. N., The time of judgment in psychometric measures. Am. 1. Psychol., 43, 65-86 ( 1931 ). Kru.:VGER, L. E., Effect of bracketing lines on speed of "same"-"different" judgments of two adjacent letters. 1. exp. Psychol., 84, 324-330 (1970). MCINISH, J. R., and TIKOFSKY, R. S., Distinctive features and response latencies: A pilot study. Percept. Psychophys., 6, 267-268 (1969). MILLER, G. A., and NICELY, P., An analysis of perceptual confusions among some English consonants. 1. acoust. Soc. Am., 27, 338-352 (1955). NICKERSON, R. S., Response times for "same"-"different judgments. Percept. Mot. Skills, 20, 15-18 (1965). NICKERSON, R. S., Same-different response times: A further test of a 'counter and clock' model. Acta Psychologica, 35, 112-127 ( 1971 ). NISHISATO, S., arid WISE, J. S., Relative probability, interstimulus interval, and speed of the same-different judgment. Psychon. Sci., 7, 59-60 (1967). OWENS, E., BENEDICT, M., and SCmJBEnT, E. D., Consonant phonemic errors associated with pure-tone configurations and certain kinds of hearing impairment. ]. Speech Hearing Res., 15, 308-322 (1972). REED, C. M., Reaction times for a same-different discrimination of vowel-consonant syllables. Percept. Psychophys. 18, 65-70 (1975). SINCH, S., A distinctive-feature analysis of responses to a multiple-choice intelligib':lity test. Int. Rev. appl. Ling., NI/I, 37-53 (1968). 790 Journal of Speech and Hearing Research


i8

773-794

1975

TVERSKY, B., Pictorial and verbal encoding in a short-term memory task. Percept. Psychophys., 6, 225-233 (1969). WALDEN, B. E., and MONTCOMErW, A. A., Dimensions of consonant perception in normal and hearing-impaired listeners. I. Speech Hearing Res., 18, 444-455 (1975). WAr.KEn, H. M., and LED, J., Statistical Inference. New York: Henry Holt (1953). WANC, M. D., and BILCER, R. C., Consonant confusions in noise: A study of perceptual features. J. acoust. Soc. Am., 54, 1248-1266 (1973). WlCXELCREN, W. A., Distinctive features and errors in short-term memory for English consonants. J. aco~st. Soc. Am., 39, 388-398 (1966). Received April 17, 1975. Accepted August 22, 1975.



791

oo~oooo~ .~,.~

~176176 9

o

o

o

o

~

o

.

~.~.~ ~,~ ~

~

o

R~.~

~

~-~ ~~

I I I I I I I I

~ 1 1 1 1 1 1

~

~

1

~

~

~

1

~

.~ ~, .~. ~ "~:~ ~

~ ~

~

~.N 9

X~

v

792

v

1ournal of Speech and Hearing Research


18

773-794

1975

APPENDIX

B

False-alarm (FA) rates and d' values for individual phonemic comparisons for subjects whose data were not presented in text. Given the input characteristics of the matrices from which these d' values were derived (200 same trials and 100 different trials), the largest possible d' (for one error of each type) is 4.90. This number has been used as an approximation of d' when either P(SId ) or P(DIs) is 0. Asterisks denote d' values that were below the 95% confidence intervals obtained [rom data for normal subjects (Reed, 1975), given in the final column of Table 5 in the text.

Phonemic Comparison

1

2

4(R)

4(L)

0.72 1.09*

0.87 2.61

0.33 2.50

0.38 2.26*

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4,90

0.00 4.90

0.00 4.90

Sub/ect 6

7

9

10

0.63 1.45"

0.28 1.88"

0.45 2.08*

0.75 2.29*

0.03 4.03

0.00 4.90

0.05 3.24

0.03 3.63

0.00 4.62

0.00 4.90

0.41 2.28

0.06 3.12

0.59 1.24"

0.59 1.65"

0.07 2.51

0.00 4.90

0.00 4.90

0.03 3.61

0.07 3.14

0.04 3.44

0.20 2.09*

0.27 1.83"

0.08 3.55

0.00 4.90

0.02 4.21

0.05 4.20

0.04 3.89

0.02 3.75

0.18 2.67*

0.12 2.12"

FA d' /d5-d/ FA d' /d3-f FA d'

0.00 4.90

0.00 4.90

0.08 4.90

0.02 3.37

0.00 4.90

0.01 3.84

0.17 2.12"

0.09 2.30*

0.00 4.90

0.00 4.90

0.01 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.04 3.50

0.01 3.08

0.00 4.90

0.00 4.90

0.00 4.64

0.00 4.90

0.00 4.90

0.00 4.90

0.08 3.10

0.08 2.30

FA d' /5-d3/ FA d'

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.01 4.90

0.07 3.80

0.06 2.91

0.00 4.90

0.00 4.90

0.00 4.90

0.01 4.89

0.00 4.90

0.00 4.90

0.02 3.03*

0.14 2.21"

0.00 , 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.02 3.23

0.04 3.22

0.02 4.36

0.07 4.90

0.00 -3.38

0.05 3.37

0.00 4.90

0.01 3.80

0.53 1.57"

0.66 0.75*

0.05 4.90

0.00 4.90

0.00 4.90

0.11 3.02

0.01 3.95

0.07 3.21

0.30 1.78"

0.00 4.90

0.01 4.27

0.00 4.90

0.00 4.90

0.19 2,45*

0.19 2.42*

0.18 2.14"

0.25 1.96"

0.45 1.08"

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

0.02 3.78

0.01 3.92

0.14 2.38*

0.25 2.21"

0.00

0.00

0.00

0.05

0.00

0.01

0.30

0.00

/5-d/ FA d'

/d-0/ FA d'

/d-v/ FA d'

/6-gl FA d' /d3-tl/ FA d'

/ds-g/

/3-f/

15-gl FA d'

13-~I FA d' /g-k/ FA d'

/g-d/ FA d'

19-~1 FA d'

~g-o~ FA



793

Appendix B (Cont.) Phonemic Comparison d' /t-d/ FA dI /t-s/ FA d'

Subject 6

1

2

4(R)

4(I.,)

4.90

4.90

4.90

3.51

4.90

0.00 4.90

0.05 4.90

0.00 4.90

0.01 4.36

0.00 4.90

0.00 4.90

0.02 4.62

0.00 4.90

0.00 4.90

0.00 4.90

0.00 4.90

7

9

10

3.80

1.72"

4.63

0.00 4.90

0.04 3.03*

0.02 4.38

0.00 4.90

0.01 4.90

0.00 4.90

0.18 2.72*

0.00 4.90

0.59 0.97*

0.00 4.90

0.01 4.90

0.00 4.90

0.02 3.48

0.00 4.90

0.04 2.69*

0.00 4.90

0.01 4.90

0.00 4.90

0.01 3.66

0.00 4.90

0.01 3.23

It-v~ FA d' /t-z/ FA d'

APPENDIX C T h e size of the difference, in msec, b e t w e e n m e a n correct "different" a n d "same" RTs ( D -- S ) for individual p h o n e m i c comparisons. For each comparison, the "same" RT is the m e a n of 200 observations a n d the "different" RT is the mean of 100 observations. T h e size of D -- S is given here for the seven subjects whose results were not presented in the text. Asterisks denote D - S values that were below the lower b o u n d of the 95% normal confidence intervals given in Table 7. T h e average D -- S values across comparisons contrasting an equal n u m b e r of features do not include values for comparisons where P ( S l d ) exceeded 0.60.

Contrasts

1

1-feature /5-d/ 382.0 /5-0/ 74.0 /5-v/ 206.0 /g-k/ 133.0 /9-0/ 62.0 /ds-tJ'/ 153.0 /ds-g/ 27.0 /5-I/ 124.0 /5-d5/ 15.0 /5-z/ 176.0 /t-d/ 165.0 Average 113.5 2-feature /5-9/ 74.0 /t-s/ 187.0 /ds-d/ 40.0 Average 100.3 3-feature /g-d/ 86.0 /t-v/ 123.0 /t-z/ 120.0 Average 109.7 4- and 5-feature /5-g/ 18.0 /g-0/ 0.0 /ds-f/ 3.0 Average 7.0 794

2

Subject 6

4 (RE)

4 (LE)

89.0 209.0 105.0 146.0 46.0 186.0 -- 15.0 153.0 87.0 205.0 -24.0 107.9

151.0 - 67.0" 56.0 52.0 --44.0* 31.0 -- 77.0* -- 14.0 -106.0" 30.0* -71.0" - 5.4

80.0 58.0 160.0 37.0 --34.0* 18.0 --56.0 -- 34.0* -102.0" 47.0* -13.0 14.6

625.0 - 71.0" 7.0* -- 29.0* 41.0 141.0 -- 19.0 - 91.0" -106.0" - 108.0" -56.0* - 29.4

140.0 165.0 219.0 174.7

-89.0" 64.0 -90.0" - 38.3

--64.0" 97.0 --2.0 10.3

53.0 68.0 42.0 54.3

-60.0* - 47.0* -49.0* - 52.0 --73.0 122.0" --58.0* -84.3

32.0 43.0 3.0 26.0

-

-

7

9

10

61.0 - 59.0* 54.0* 34.0 -- 124.0" - 198.0" - 152.0" 75.0 -177.0" - 15.0" -15.0 - 46.9

139.0 6.0 162.0 50.0 -- 11.0" - 14.0" 35.0 - 44.0* -32.0 154.0 -54.0* 35.5

249.0 - 99.0* 23.0* 25.0 64.0 160.0 56.0 42.0 15.0 38.0* -51.0" 27.3

-168.0" -36.0* -91.0" - 98.3

-82.0" 150.0 - 149.0" - 27.0

6.0 4.0* - 88.0* - 26.0

-33.0 75.0 --78.0" - 12.0

-73.0* - 13.0 -111.0" - 65.7

241.0 - 169.0" -186.0" - 38.0

119.0 - 45.0* 71.0 48.3

0.0 - 79.0* -127.0" - 68.7

168.0 9.0 19.0 65.3

--45.0 - 30.0 --82.0* --52.3

63.0 --71.0" --120.0" --42.6

-- 100.0 -- 103.0" -198.0" -- 133.7

85.0 4.0 --70.0* 6.3

94.0 --99.0" 17.0 4.0

Journal o[ Speech and Hearing Research


18

773-794

1975

Complex-Tone Pitch Discrimination in Listeners With Sensorineural Hearing Loss.

Speech discrimination tests in investigation of sensorineural hearing loss.

Factors Affecting Sentence-in-Noise Recognition for Normal Hearing Listeners and Listeners with Hearing Loss.

Autoimmune sensorineural hearing loss.

P300 in individuals with sensorineural hearing loss.

Bullous myringitis with sensorineural hearing loss.

Sensorineural hearing loss with low dose erythromycin.

Unilateral sensorineural hearing loss rehabilitation.

Idiopathic Sudden Sensorineural Hearing Loss With Minimal Hearing Impairment.

Temporal and masking phenomena in persons with sensorineural hearing loss.

Sensorineural hearing loss in hemorrhagic dengue?

Pseudoexfoliation syndrome and sensorineural hearing loss.

IgG4-Related Disease and Sensorineural Hearing Loss.

Acupuncture and sensorineural hearing loss: a review.

Acupuncture and sensorineural hearing loss: a review.

Idiopathic sudden sensorineural hearing loss in Japan.

Sensorineural hearing loss in juvenile chronic arthritis.

Improvement in sensorineural hearing loss during pregnancy.

Vibrant Soundbridge rehabilitation of sensorineural hearing loss.

Idiopathic sensorineural hearing loss in the only hearing ear.

[Subclinical sensorineural hearing loss in female patients with rheumatoid arthritis].

Sensorineural hearing loss in patients with Kawasaki disease.

Sensorineural hearing loss in pediatric patients with celiac disease.

Epileptiform electroencephalogram abnormality in children with congenital sensorineural hearing loss.