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Background There is an increasing need to administer hearing tests outside of sound-attenuating rooms. Maximum permissible ambient noise levels (MPANLs) from published in standards (Occupational Health and Safety Administration [OSHA] 1983; American National Standards Institute [ANSI] S3.1–1999 (R2018)) can be modified to account for the additional attenuation provided by circumaural earphones (relative to supra-aural earphones) that are used for pure-tone audiometry. Ambient noise can influence the results of pure-tone audiometry by elevating thresholds by direct masking and by producing distractions that affect the accuracy of the test. The effects of these distractions have not been studied in relation to pure-tone audiometry in adult listeners. Purpose In Part I MPANLs provided by ANSI and OSHA standards are extended to account for the greater attenuation provided by circumaural earphones. Rules (“alerts”) were developed taking into account the listeners' thresholds. In Part II effects of distracting noise on pure-tone thresholds are reported. Methods and Results In Part I MPANLs two standards were modified for circumaural earphones by adding the additional attenuation provided by three circumaural earphones (relative to supra-aural earphones). A set of rules (“alerts”) is provided for identifying masking effects from ambient noise in a variety of conditions (earphone type, threshold elevation, uncovered ear). In Part II the distracting effects of an industrial noise sample on thresholds obtained from five listeners with normal hearing are described. Pure-tone thresholds were measured in quiet and in distracting noise presented at various levels. The effects of the distracting noise on the following variables were measured: time per trial, number of trials required to measure threshold, threshold shift, and perceived distractibility of the noise. Time per trial was unaffected by distracting noise. Number of trials required for threshold, threshold shift, and perceived distractibility increased with distracting noise level. Conclusion Part I: The modified MPANLs provide more relevant determinations of the potential effects of ambient noise on pure-tone thresholds than the values in the standards. Part II: Distracting noise affects pure-tone threshold measurements in a manner that is different from direct masking. The potential contaminating effect of distracting noise can be measured and reported.

The Auditec of St. Louis and the Department of Veterans Affairs (VA) recorded versions of the Northwestern University Auditory Test No. 6 (NU-6) are in common usage. Data on young adults with normal hearing for pure tones (YNH) demonstrate equal recognition performances on the two versions when the VA version is presented 5 dB higher but similar data on older listeners with sensorineural hearing loss (OHL) are lacking.To compare word-recognition performances on the Auditec and VA versions of NU-6 presented at six presentation levels with YNH and OHL listeners.A quasi-experimental, repeated-measures design was used.Twelve YNH (M = 24.0 years; PTA = 9.9-dB HL) and 36 OHL listeners (M = 71.6 years; PTA = 26.7-dB HL) participated in three, one-hour sessions.Each listener received 100 stimulus words that were randomized by 6 presentation levels for each of two speakers (YNH, −2 to 28-dB SL; OHL, −2 to 38-dB SL). The sessions were limited to 25 practice and 400 experimental words. Digital versions of the 16, 25-word tracks for each session were alternated between speakers.Each of the 48 listeners had higher recognition performances on the Auditec version of NU-6 than on the VA version. The respective overall recognition performances on the Auditec and VA versions were 71.4% and 64.1% (YNH) and 68.7% and 58.2% (OHL). At the highest presentation levels, recognition performances on the two versions differed by only 0.5% (YNH) and 3.3% (OHL). At the 50% correct point, performances on the Auditec version were 3.2 dB (YNH) and 6.1 dB (OHL) better than those on the VA version. The slopes at the 50% points on the mean functions for both speakers were about 4.9%/dB (YNH) and 3.0%/dB (OHL); however, the slopes evaluated from the individual listener data were steeper, 5.2 to 5.3%/dB (YNH) and 3.3 to 3.5%/dB (OHL). When the individual data were transformed from dB SL to dB HL, the differences between the two listener groups were emphasized. The four functions (2 speakers by 2 listener groups) were plotted for each of the 48 participants and each of the 200 words, which revealed the gamut of relations among the datasets. Examination of the data for each speaker across test sessions, in the traditional 50-word lists, and in the typically used 25-word lists of Randomization A revealed no differences of clinical concern. Finally, introspective reports from the listeners revealed that 91.7% and 83.3% of the YNH and OHL listeners, respectively, thought the Auditec speaker was easier to understand than the VA speaker. Recognition performances on each participant and on each word are presented.

Background: In the 1950s, with monitored live voice testing, the vu meter time constant and the shortdurations and amplitude modulation characteristics of monosyllabic words necessitated the use of the carrierphrase amplitude tomonitor (indirectly) the presentation level of the words. This practice continues withrecorded materials. To relieve the carrier phrase of this function, first the influence that the carrier phrasehas on word recognition performance needs clarification, which is the topic of this study.Purpose: Recordings of Northwestern University Auditory Test No. 6 by two female speakers were usedto compare word recognition performances with and without the carrier phrases when the carrier phraseand test word were (1) in the same utterance stream with the words excised digitally from the carrier (VA-1speaker) and (2) independent of one another (VA-2 speaker). The 50-msec segment of the vowel in thetarget word with the largest root mean square amplitude was used to equate the target word amplitudes.Research Design: A quasi-experimental, repeated measures design was used.Study Sample: Twenty-four young normal-hearing adults (YNH; M = 23.5 years; pure-tone average[PTA] = 1.3-dB HL) and 48 older hearing loss listeners (OHL; M = 71.4 years; PTA = 21.8-dB HL) participatedin two, one-hour sessions.Data Collection and Analyses: Each listener had 16 listening conditions (2 speakers 3 2 carrier phraseconditions 3 4 presentation levels) with 100 randomized words, 50 different words by each speaker.Each word was presented 8 times (2 carrier phrase conditions 3 4 presentation levels [YNH, 0- to24-dB SL; OHL, 6- to 30-dB SL]). The 200 recorded words for each condition were randomized as 8,25-word tracks. In both test sessions, one practice track was followed by 16 tracks alternated betweenspeakers and randomized by blocks of the four conditions. Central tendency and repeated measuresanalyses of variance statistics were used.Results: With the VA-1 speaker, the overall mean recognition performances were 6.0% (YNH) and 8.3%(OHL) significantly better with the carrier phrase than without the carrier phrase. These differences werein part attributed to the distortion of some words caused by the excision of the words from the carrierphrases. With the VA-2 speaker, recognition performances on the with and without carrier phrase conditionsby both listener groups were not significantly different, except for one condition (YNH listeners at8-dB SL). The slopes of the mean functions were steeper for the YNH listeners (3.9%/dB to 4.8%/dB) thanfor the OHL listeners (2.4%/dB to 3.4%/dB) and were Conclusion: The current data indicate that word recognition performances with and without the carrierphrase (1) were different when the carrier phrase and target word were produced in the same utterancewith poorer performances when the target words were excised from their respective carrier phrases(VA-1 speaker), and (2) were the same when the carrier phrase and target word were produced as independentutterances (VA-2 speaker).See the Supplementary Data tab for supplementary materials.

Background: In developing the PB-50 word lists, J. P. Egan suggested five developmental principles, two of which were “equal average difficulty” and an “equal range of difficulty” among the lists (page 963). Egan was satisfied that each of the 20 PB-50 lists had equivalent ranges of recognition performances and that the lists produced the same average performances. This was accomplished in preliminary studies that measured the recognition performance of each word and eliminated words that were always or never correct. In preparing for studies of interrupted words, we needed to know the range of difficulty inherent in the speaker specific NU-6 and Maryland CNC materials we planned to use when those words were not interrupted. There were only a few studies in the literature that touched on the range of difficulty characteristic of the word-recognition materials in common usage. The paucity of this information prompted this investigation whose scope broadened to include the CID W-22, Maryland CNC, NU-6, and PB-50 materials spoken by a variety of speakers. Purpose: The purpose was to evaluate the homogeneity with respect to intelligibility of the words that comprise several of the common word-recognition materials used in audiologic evaluations. Research Design: Both retrospective (10) and prospective (3) studies were involved. Data from six of the retrospective studies were from our labs. The prospective studies involved both listeners with normal hearing for pure tones and listeners with sensorineural hearing loss. Study Sample: The sample sizes for the 13 data sets ranged from 24 to 1,030, with 24 the typical number for listeners with normal hearing. Data Collection and Analysis: The retrospective data were from published studies and archived data from our laboratories. The prospective studies involved presentation of the word-recognition materials to the listeners at a comfortable level. An item analysis was conducted on each data set with descriptive statistics used to characterize the data. Additionally, skewness coefficients were calculated on the distributions of word performances and the interquartile range was used to determine minor and major outliers within each set of 200 words and their component 50-word lists (300 words for the Maryland CNCs). Results: For listeners with normal hearing the majority of performances on the words within a 50-word list were better than the mean performance, which produced negatively skewed distributions with outlier performances in every list. For listeners with sensorineural hearing loss the performances on the words within a 50-word list were evenly distributed above and below the mean performance, which yielded essentially normal distributions with few outliers. There were a few words on which performances were better by the listeners with hearing loss. Conclusions: Every list of word-recognition materials has a few words on which recognition performances are noticeably poorer than performances on the majority of the remaining words. If the intention of an experiment is to evaluate performance at the word level, then identifying these “outliers” becomes a necessity. Although not evaluated in this report, the implications for 25-word lists are they should be based on recognition-performance data and not compiled arbitrarily.

Background: The authors reviewed the evidence regarding the existence of age-related declines in central auditory processes and the consequences of any such declines for everyday communication. Purpose: This report summarizes the review process and presents its findings. Data Collection and Analysis: The authors reviewed 165 articles germane to central presbycusis. Of the 165 articles, 132 articles with a focus on human behavioral measures for either speech or nonspeech stimuli were selected for further analysis. Results: For 76 smaller-scale studies of speech understanding in older adults reviewed, the following findings emerged: (1) the three most commonly studied behavioral measures were speech in competition, temporally distorted speech, and binaural speech perception (especially dichotic listening); (2) for speech in competition and temporally degraded speech, hearing loss proved to have a significant negative effect on performance in most of the laboratory studies; (3) significant negative effects of age, unconfounded by hearing loss, were observed in most of the studies of speech in competing speech, time-compressed speech, and binaural speech perception; and (4) the influence of cognitive processing on speech understanding has been examined much less frequently, but when included, significant positive associations with speech understanding were observed.For 36 smaller-scale studies of the perception of nonspeech stimuli by older adults reviewed, the following findings emerged: (1) the three most frequently studied behavioral measures were gap detection, temporal discrimination, and temporal-order discrimination or identification; (2) hearing loss was seldom a significant factor; and (3) negative effects of age were almost always observed.For 18 studies reviewed that made use of test batteries and medium-to-large sample sizes, the following findings emerged: (1) all studies included speech-based measures of auditory processing; (2) 4 of the 18 studies included nonspeech stimuli; (3) for the speech-based measures, monaural speech in a competing-speech background, dichotic speech, and monaural time-compressed speech were investigated most frequently; (4) the most frequently used tests were the Synthetic Sentence Identification (SSI) test with Ipsilateral Competing Message (ICM), the Dichotic Sentence Identification (DSI) test, and time-compressed speech; (5) many of these studies using speech-based measures reported significant effects of age, but most of these studies were confounded by declines in hearing, cognition, or both; (6) for nonspeech auditory-processing measures, the focus was on measures of temporal processing in all four studies; (7) effects of cognition on nonspeech measures of auditory processing have been studied less frequently, with mixed results, whereas the effects of hearing loss on performance were minimal due to judicious selection of stimuli; and (8) there is a paucity of observational studies using test batteries and longitudinal designs. Conclusions: Based on this review of the scientific literature, there is insufficient evidence to confirm the existence of central presbycusis as an isolated entity. On the other hand, recent evidence has been accumulating in support of the existence of central presbycusis as a multifactorial condition that involves age- and/or disease-related changes in the auditory system and in the brain. Moreover, there is a clear need for additional research in this area.

Background: Since the 1940s, measures of pure-tone sensitivity and speech recognition in quiet have been vital components of the audiologic evaluation. Although early investigators urged that speech recognition in noise also should be a component of the audiologic evaluation, only recently has this suggestion started to become a reality. This report focuses on the Words-in-Noise (WIN) Test, which evaluates word recognition in multitalker babble at seven signal-to-noise ratios and uses the 50% correct point (in dB SNR) calculated with the Spearman-Kärber equation as the primary metric. The WIN was developed and validated in a series of 12 laboratory studies. The current study examined the effectiveness of the WIN materials for measuring the word-recognition performance of patients in a typical clinical setting. Purpose: To examine the relations among three audiometric measures including pure-tone thresholds, word-recognition performances in quiet, and word-recognition performances in multitalker babble for veterans seeking remediation for their hearing loss. Research Design: Retrospective, descriptive. Study Sample: The participants were 3430 veterans who for the most part were evaluated consecutively in the Audiology Clinic at the VA Medical Center, Mountain Home, Tennessee. The mean age was 62.3 yr (SD = 12.8 yr). Data Collection and Analysis: The data were collected in the course of a 60 min routine audiologic evaluation. A history, otoscopy, and aural-acoustic immittance measures also were included in the clinic protocol but were not evaluated in this report. Results: Overall, the 1000–8000 Hz thresholds were significantly lower (better) in the right ear (RE) than in the left ear (LE). There was a direct relation between age and the pure-tone thresholds, with greater change across age in the high frequencies than in the low frequencies. Notched audiograms at 4000 Hz were observed in at least one ear in 41% of the participants with more unilateral than bilateral notches. Normal pure-tone thresholds (≤20 dB HL) were obtained from 6% of the participants. Maximum performance on the Northwestern University Auditory Test No. 6 (NU-6) in quiet was ≥90% correct by 50% of the participants, with an additional 20% performing at ≥80% correct; the RE performed 1–3% better than the LE. Of the 3291 who completed the WIN on both ears, only 7% exhibited normal performance (50% correct point of ≤6 dB SNR). Overall, WIN performance was significantly better in the RE (mean = 13.3 dB SNR) than in the LE (mean = 13.8 dB SNR). Recognition performance on both the NU-6 and the WIN decreased as a function of both pure-tone hearing loss and age. There was a stronger relation between the high-frequency pure-tone average (1000, 2000, and 4000 Hz) and the WIN than between the pure-tone average (500, 1000, and 2000 Hz) and the WIN. Conclusions: The results on the WIN from both the previous laboratory studies and the current clinical study indicate that the WIN is an appropriate clinic instrument to assess word-recognition performance in background noise. Recognition performance on a speech-in-quiet task does not predict performance on a speech-in-noise task, as the two tasks reflect different domains of auditory function. Experience with the WIN indicates that word-in-noise tasks should be considered the “stress test” for auditory function.

Background: The most common complaint of adults with hearing loss is understanding speech in noise. One class of masker that may be particularly useful in the assessment of speech-in-noise abilities is interrupted noise. Interrupted noise usually is a continuous noise that has been multiplied by a square wave that produces alternating intervals of noise and silence. Wilson and Carhart found that spondaic word thresholds for listeners with normal hearing were 28 dB lower in an interrupted noise than in a continuous noise, whereas listeners with hearing loss experienced only an 11 dB difference. Purpose: The purpose of this series of experiments was to determine if a speech-in-interrupted-noise paradigm differentiates better (1) between listeners with normal hearing and listeners with hearing loss and (2) among listeners with hearing loss than do traditional speech-in-continuous-noise tasks. Research Design: Four descriptive/quasi-experimental studies were conducted. Study Sample: Sixty young adults with normal hearing and 144 older adults with pure-tone hearing losses participated. Data Collection and Analysis: A 4.3 sec sample of speech-spectrum noise was constructed digitally to form the 0 interruptions per second (ips; continuous) noise and the 5, 10, and 20 ips noises with 50% duty cycles. The noise samples were mixed digitally with the Northwestern University Auditory Test No. 6 words at selected signal-to-noise ratios and recorded on CD. The materials were presented through an earphone, and the responses were recorded and analyzed at the word level. Similar techniques were used for the stimuli in the remaining experiments. Results: In Experiment 1, using 0 ips as the reference condition, the listeners with normal hearing achieved 34.0, 30.2, and 28.4 dB escape from masking for 5, 10, and 20 ips, respectively. In contrast, the listeners with hearing loss only achieved 2.1 to 2.4 dB escape from masking. Experiment 2 studied the 0 and 5 ips conditions on 72 older listeners with hearing loss, who were on average 13 yr younger and more varied in their hearing loss than the listeners in Experiment 1. The mean escape from masking in Experiment 2 was 7 dB, which is 20–25 dB less than the escape achieved by listeners with normal hearing. Experiment 3 examined the effects that duty cycle (0–100% in 10% steps) had on recognition performance in the 5 and 10 ips conditions. On the 12 young listeners with normal hearing, (1) the 50% correct point increased almost linearly between the 0 and 60% duty cycles (slope = 4.2 dB per 10% increase in duty cycle), (2) the slope of the function was steeper between 60 and 80% duty cycles, and (3) about the same masking was achieved for the 80–100% duty cycles. The data from the listeners with hearing loss were inconclusive. Experiment 4 varied the interburst ratios (0, –6, –12, –24, –48, and –∞ dB) of 5 ips noise and evaluated recognition performance by 24 young adults. The 50% points were described by a linear regression (R 2 = 0.98) with a slope of 0.55 dB/dB. Conclusion: The current data indicate that interrupted noise does provide a better differentiation both between listeners with normal hearing and listeners with hearing loss and among listeners with hearing loss than is provided by continuous noise.

Purpose: To analyze the 50% correct recognition data that were from the Wilson et al (this issue) study and that were obtained from 24 listeners with normal hearing; also to examine whether acoustic, phonetic, or lexical variables can predict recognition performance for monosyllabic words presented in speech-spectrum noise. Research Design: The specific variables are as follows: (a) acoustic variables (i.e., effective root-mean-square sound pressure level, duration), (b) phonetic variables (i.e., consonant features such as manner, place, and voicing for initial and final phonemes; vowel phonemes), and (c) lexical variables (i.e., word frequency, word familiarity, neighborhood density, neighborhood frequency). Data Collection and Analysis: The descriptive, correlational study will examine the influence of acoustic, phonetic, and lexical variables on speech recognition in noise performance. Results: Regression analysis demonstrated that 45% of the variance in the 50% point was accounted for by acoustic and phonetic variables whereas only 3% of the variance was accounted for by lexical variables. These findings suggest that monosyllabic word-recognition-in-noise is more dependent on bottom-up processing than on top-down processing. Conclusions: The results suggest that when speech-in-noise testing is used in a pre- and post-hearing-aid-fitting format, the use of monosyllabic words may be sensitive to changes in audibility resulting from amplification.

Dichotic word recognition was evaluated in free-recall, directed-attention right, and directed-attention left response conditions. All participants were right-handed and included a group of young adults with normal hearing and two groups of older adults with sensorineural hearing loss. Dichotic word recognition performance was best for young adults and decreased for each older group. A right-ear advantage (REA) was observed for all groups. REAs observed in the older groups were larger than those for the young adults, resulting from a greater deficit in dichotic word recognition performance for words presented to the left ear. A subset of older adults exhibited few to no responses (≤3/100) for the left ear for all response conditions, which may relate to a compromise in auditory processing. The results support an age-related disadvantage in recognition performance for dichotic stimuli presented to the left ear not entirely accounted for by differences in hearing sensitivity between subject groups.

The purpose of this study was to determine the list equivalency of the 18 QuickSIN™ (Quick Speech in Noise test) lists. Individuals with normal hearing (n = 24) and with sensorineural hearing loss (n = 72) were studied. Mean recognition performances on the 18 lists by the listeners with normal hearing were 2.8 to 4.3 dB SNR (signal-to-noise ratio), whereas the range was 10.0 to 14.3 dB SNR for the listeners with hearing loss. The psychometric functions for each list showed high performance variability across lists for listeners with hearing loss but not for listeners with normal hearing. For listeners with hearing loss, Lists 4, 5, 13, and 16 fell outside of the critical difference. The data from this study suggest nine lists that provide homogenous results for listeners with and without hearing loss. Finally, there was an 8.7 dB difference in performances between the two groups indicating a more favorable signal-to-noise ratio required by the listeners with hearing loss to obtain equal performance.

The purpose of this study was to determine if performances on a 500 Hz MLD task and a word-recognition task in multitalker babble covaried or varied independently for listeners with normal hearing and for listeners with hearing loss. Young listeners with normal hearing (n = 25) and older listeners (25 per decade from 40–80 years, n = 125) with sensorineural hearing loss were studied. Thresholds at 500 and 1000 Hz were ≤30 dB HL and ≤40 dB HL, respectively, with thresholds above 1000 Hz

A simple word-recognition task in multitalker babble for clinic use was developed in the course of four experiments involving listeners with normal hearing and listeners with hearing loss. In Experiments 1 and 2, psychometric functions for the individual NU No. 6 words from Lists 2, 3, and 4 were obtained with each word in a unique segment of multitalker babble. The test paradigm that emerged involved ten words at each of seven signal-to-babble ratios (S/B) from 0 to 24 dB. Experiment 3 examined the effect that babble presentation level (70, 80, and 90 dB SPL) had on recognition performance in babble, whereas Experiment 4 studied the effect that monaural and binaural listening had on recognition performance. For listeners with normal hearing, the 90th percentile was 6 dB S/B. In comparison to the listeners with normal hearing, the 50% correct points on the functions for listeners with hearing loss were at 5 to 15 dB higher signal-to-babble ratios.

The purpose of this series of experiments was to develop a simple, 500-Hz masking-level difference (MLD) protocol that could be implemented easily in the clinic to assess auditory perceptual abilities using an audio compact disc. Five, 300-ms tones with 250-ms intertone intervals were embedded in 3-s bursts of 200-800 Hz noise presented at 42.2-dB pressure-spectrum level with 4-5 s inter-stimulus intervals. The homophasic and antiphasic conditions were interleaved with the signal-to-noise ratios decreasing in 2-dB steps. A single-interval, "yes/no" response task was used. Three experiments were performed on 24-28 listeners with normal hearing. The mean SoNo thresholds (58.1- to 59.5-dB SPL) and the mean SπNo thresholds (45.1- to 46.0-dB SPL) produced ˜13-dB MLDs. Experiment 3 included a SoNπ condition that had a mean threshold of 48.8-dB SPL and a 10.0-dB MLD. The mean test, retest ot the SoNo and SπNo thresholds on 15 listeners was

The sentence stimuli developed in this project combined aspects from several traditional approaches to speech audiometry. Sentences varied with respect to frequency of word use and phonetic confusability. Familiar consonant-vowel-consonant words, nouns and modifiers, were used to form 500 sentences of seven to nine syllables. Based on concepts from the Neighborhood Activation Model for spoken word recognition, each sentence contained three key words that were all characterized as high- or low-use frequency and high or low lexical confusability. Use frequency was determined by published indices of word use, and lexical confusability was defined by a metric based on the number of other words that were similar to a given word using a single phoneme substitution algorithm. Thirty-two subjects with normal hearing were randomly assigned to one of seven presentation levels in quiet, and an additional 32 listeners were randomly assigned to a fixed-level noise background at one of six signal-to-noise ratios. The results indicated that in both quiet and noise listening conditions, high-use words were more intelligible than low-use words, and there was an advantage for phonetically unique words; the position of the key word in the sentence was also a significant factor. These data formed the basis for a sequence of experiments that isolated significant nonacoustic sources of variation in spoken word recognition. Abbreviations: CVC = consonant-vowel-consonant, HD = high frequency of use word from a dense neighborhood, HS = high frequency of use word from a sparse neighborhood, LD = low frequency of use word from a dense neighborhood, LS = low frequency of use word from a sparse neighborhood, NAM = Neighborhood Activation Model, SIN = Speech in Noise, SNR = signal-to-noise ratio

An option for estimating the word-recognition performance of patients who do not speak English as a first language involves using auditory materials, presented in the patient’s native language, in conjunction with a closed-set response mode incorporating pictures or written words. The advantage of this auditory/visual paradigm is that the audiologist is not required to know the foreign language and is therefore not required to judge the accuracy of an oral response to speech stimuli in a foreign language. Spanish auditory/visual materials, known as the Spanish Picture-Identification Task, were developed to be used in a computer- driven multimedia administration and scoring format. Performance data, both in open- (word-recognition) and closed-set (word-identification) response modes, were established for the Spanish Picture-Identification Task using subjects whose first language was Spanish. The results from the open-set paradigm indicate that the Spanish Picture-Identification Task word lists are essentially equivalent to conventional Spanish and English materials used for word recognition. Findings from the closed-set conditions indicate that the Spanish Picture- Identification Task materials are appropriate for estimating the word-identification abilities of Spanish-speaking adult listeners.

Four patients who preferred monaural as compared with binaural amplification were evaluated. For these patients, audiometric data, recognition performance on a dichotic digit task, and monaural and binaural hearing aid performance using four amplification strategies (National Acoustic Laboratories-Revised, a speech in noise algorithm, multiple-microphone arrays, and frequency modulated [FM]) are described. The results of dichotic testing using a one-, two-, and three-pair dichotic digit task in free- and directed-recall conditions indicated a left-ear deficit for all subjects that could not be explained by peripheral auditory findings or by a cognitive-based deficit. The results of soundfield testing using a speech in multitalker babble paradigm indicated that when listening in noise, there was little difference between aided and unaided word-recognition performance, suggesting that the binaural hearing aids originally fit for each patient were not providing substantial benefit when listening in a competing babble background. Word-recognition performance when aided monaurally in the right ear was superior to performance when aided monaurally in the left ear and when aided bin- aurally. The only successful binaural amplification strategy was the FM system. The results indicate that listeners with an auditory-based deficit in dichotic listening may function better with a monaural hearing aid fitting or with an assistive listening device such as an FM system. The findings also suggest that a test of dichotic listening is an important component in the evaluation of patients being considered for amplification. Abbreviations: ALD = assistive listening device, BTE = behind the ear, DM = directional microphone, FM = frequency modulated, ITE = in the ear, NAL-R = National Acoustic Laboratories-Revised, NU-6 = Northwestern University Auditory Test No. 6, S/B = signal-to-babble ratio, S/N - signal-to-noise ratio

Dichotic listening was evaluated using monosyllabic word pairs that differed in lexical difficulty as defined by the Neighborhood Activation Model of spoken word recognition. Four combinations of lexically EASY and lexically HARD words were evaluated (same pair: EASY-EASY, HARD-HARD; or mixed pair: EASY-HARD, HARD-EASY) in young adult listeners with normal hearing and older adult listeners with mild-to-moderate hearing loss. The same-pair data indicated that for all subjects, EASY words were identified correctly more often than HARD words, and recognition performance on words presented to the right ear was better than performance on words presented to the left ear. Overall performance was lower and the right-ear advantage was larger for the older group. The mixed-pair data for the young group revealed that EASY words were recognized more accurately than HARD words, regardless of the ear to which they were presented. For the older adults, the words presented to the right ear were recognized more accurately than were the words presented to the left ear, regardless of the type of word. The efficiency of the processing of stimuli from the left ear is discussed as an explanation of the results for the mixed-pair conditions. Abbreviations: ANCOVA = analysis of covariance, ANOVA = analysis of variance, CV = consonant-vowel, NAM = Neighborhood Activation Model

This tutorial paper examines the relation between the slope of a mean word recognition function and the homogeneity or variability (with respect to recognition) of the individual stimulus items that compose the test materials. This was studied in terms of both the location (Cartesian) and slope of the psychometric functions of the individual words that compose the materials. Word recognition performances were measured for 100 CID W-22 (Hirsh) words and 100 PB-50 (Rush Hughes) words in quiet (0 to 56 dB HL in 8-dB steps) on 12 subjects with normal hearing. The functions for the individual W-22 words were more homogeneous (less variable) than were the functions for the individual PB-50 words. The mean function for the W-22 words was steeper (3.1%/dB) than the function for the PB-50 words (1.9%/dB). This evaluation of the individual words demonstrates the direct relation between variability of the test items and the slope of the mean psychometric function. The more homogeneous performance is on the individual test items with respect to both location and slope, the steeper the slope of the mean psychometric function. Abbreviations: ANOVA = analysis of variance, CD = compact disc

A one-, two-, and three-pair dichotic digit test was administered to 180 subjects (20-79 years) with varying degrees of hearing sensitivity. The test was carried out under free- and directed-recall response conditions. The results indicated that recognition performance decreased as a function of increasing age. Statistical analysis using analysis of covariance indicated that differences in performance between age groups were not owing to differences in hearing sensitivity. Thus, with the effects of hearing sensitivity removed, age alone accounted for a significant portion of the variability in the data among age groups. Normative data for the free-recall condition are reported for the two lists of randomly interleaved one-, two-, and three-pair digits included on the Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 2.0 (1998) compact disc. A comparison of performance in free- and directed-recall conditions indicated three patterns of results. First, 58 percent of the subjects had normal recognition performance for one-, two-, and three-pair digits under both recall conditions. Second, 39 percent of the subjects had a deficit in the free-recall condition, with normal performance in the directed-recall condition, which was interpreted as representing primarily a cognitive problem. Third, the remaining 3 percent of the subjects showed a deficit in both free- and directed-recall conditions, which was attributed primarily to an auditory problem. Abbreviations: ANCOVA = analysis of covariance, ANOVA = analysis of variance, CD = compact disc, rau = rationalized arcsine unit

Word recognition norms were determined for the Northwestern University Auditory Test No. 6 (NU-6) released on the Department of Veterans Affairs (VA) Disc 1.1. Word recognition performance (in quiet and in competing message) was measured at 12 presentation levels for 24 young adults with normal hearing. Test-retest reliability also was evaluated. Word recognition scores for VA Disc 1.1 were generally higher than those reported for VA Disc 1.0. The differences in NU-6 scores across disc versions, however, were small and unlikely to affect clinical decisions based on word recognition tests. Score differences on test-retest for the VA Disc 1.1 version of the NU-6 with a competing message background also were small and unlikely to affect clinical outcomes. Overall, based on comparisons of scores for the disc versions of the NU-6, it appears that the two different recordings can be used interchangeably for clinical applications. Abbreviations: CD = compact disc, NU-6 = Northwestern University Auditory Test No. 6, VA = Department of Veterans Affairs, W/CML = word to competing message level

Dichotic digit listening was made more difficult by interleaving one-, two-, three-, and four-pair digits within a test list in which the subjects did not know a priori the number of digit pairs presented on a given trial, thereby introducing listener uncertainty. Twenty right-handed (mean age = 26.8 years) and 20 left-handed adults (mean age = 24.0) with normal hearing and 40 right-handed adults in the 60- to 75-years age range (mean age = 67.2) with mild-to-moderate sensorineural hearing loss were evaluated. Compared to traditional paradigms, the uncertainty of stimulus length (one, two, three, or four pairs) reduced overall recognition performance on stimuli presented to both ears of all groups, but the reduction was more pronounced for the left ear than for the right ear. The recognition performance of the right-handed subjects was more homogeneous than the performance of the left-handed subjects. In comparison to the young subjects, the 60- to 75-year-old group had substantially reduced recognition performance. Abbreviations: ANOVA = analysis of variance, CD = compact disc, CV = consonant-vowel