This research explores auditory short-term memory (STM) capacity for non-linguistic sounds in 10-month-old infants. Infants were presented with auditory streams composed of repeating sequences of either 2 or 4 unique instruments (e.g., flute, piano, cello; 350 or 700. ms in duration) followed by a 500-ms retention interval. These instrument sequences either stayed the same for every repetition (Constant) or changed by 1 instrument per sequence (Varying). Using the head-turn preference procedure, infant listening durations were recorded for each stream type (2- or 4-instrument sequences composed of 350- or 700-ms notes). Preference for the Varying stream was taken as evidence of auditory STM because detection of the novel instrument required memory for all of the instruments in a given sequence. Results demonstrate that infants listened longer to Varying streams for 2-instrument sequences, but not 4-instrument sequences, composed of 350-ms notes (Experiment 1), although this effect did not hold when note durations were increased to 700. ms (Experiment 2). Experiment 3 replicates and extends results from Experiments 1 and 2 and provides support for a duration account of capacity limits in infant auditory STM.

Background: A previous experiment with 70 interrupted monosyllabic words demonstrated that recognition performance was influenced by the location of an interruption pattern (Wilson, 2014). The interruption paradigm (10 interruptions/sec, 50% duty cycle periodic interruption) was referenced to word onset. The words were interrupted such that alternate 50-msec segments were parsed to separate files. In the 0-msec condition the first on-segment coincided with the word onset, whereas in the 50-msec condition the first on-segment occurred 50 msec after word onset. The 0- and 50-msec conditions were complementary halves. Recognition performance by young listeners was 19% better on the 0-msec condition (86%) than on the 50-msec condition (68%); there were a minority number of words on which the results were just the opposite. A second study using the same interruption paradigm but 300 different words reported similar relations, with 63% correct recognition on the 0-msec condition and 48% on the 50-msec condition (Wilson and Irish, 2015). Both studies suggest the importance that the first 50 msec of the target word has on intelligibility. Purpose: To define in detail the effects that interruption patterns have on word recognition as the interruption pattern was incremented with reference to word onset from 0 to 90 msec in 10-msec steps. Research Design: A repeated-measures design with ten interruption patterns (onset conditions). Study Sample: Twenty-four young listeners (19-29 yr) with normal hearing for pure tones participated in this study. Data Collection and Analyses: Seventy consonant-nucleus-consonant words formed the corpus of materials with 25 additional words used for practice. For each participant, the 700 stimuli (70 words by ten onset conditions) were interrupted (10 interruptions/sec; 50% duty cycle), randomized, and recorded on compact disc in 28, 25-word tracks. Results: The overall mean recognition performance was 80.4% with mean performances for the ten conditions ranging from 73.0% (50-msec condition) to 87.7% (90-msec condition). The mean recognition performances changed systematically, decreasing from the 0-msec condition to the 50-msec condition and then increasing to the 90-msec condition, which formed a U-shaped function of the means. Of the 45 mean paired comparisons (post hoc t-tests with Bonferroni corrections), there were 17 significant differences at the p ≤ 0.001 level, increasing to 31 significant differences when the significance level was increased to the p ≤ 0.01 level. Visual inspection of the 70-word performance functions revealed that 32 words had flat functions, 34 words had U-shaped functions, two functions were rising, one was an inverted V-shape, and one was irregular. Conclusions: First, some words (utterances of those words) were immune to any differential effects of the ten interruption patterns. These words with flat performance functions constituted 46% of the word corpus. Second, 49% of the words exhibited U-shaped performance functions that were always systematic, going from maximum to minimum and back to maximum. These words were thought to be more dependent on the initial consonant to attain maximum performance. The conclusion is that some words are not affected by the location of the interruption pattern (those with flat functions) whereas other words are substantially affected (those with U-shaped functions).

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 (R2=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 establish normative data for children on the Words-in-Noise Test (WIN; R. H. Wilson, 2003; R. H. Wilson & R. McArdle, 2007). Method: Forty-two children ineachof 7 age groups, rangingin age from6to12years (n = 294), and 24 young adults (age range: 18-27 years) with normal hearing for pure tones participated. All listeners were screened at 15 dB HL (American National Standards Institute, 2004) with the octave interval between 500 and 4000 Hz. Randomizations of WIN Lists 1, 2, and 1 or WIN Lists 2, 1, and 2 were presented with the noise fixed at 70 dB SPL, followed by presentation at 90 dB SPL of the 70 Northwestern University Auditory Test No. 6 (T. W. Tillman & R. Carhart, 1966) words used in the WIN. Finally, the Peabody Picture Vocabulary Test-Revised (L. M. Dunn & L. M. Dunn, 1981) was administered. Testing was conducted in a quiet room. Results: There were 3 main findings: (a) The biggest change inrecognition performance occurred between the ages of 6 and 7 years; (b) from 9 to 12 years, recognition performance was stable; and (c) performance by young adults (18-27 years) was slightly better (1-2 dB) than performance by the older children. Conclusion: The WIN can be used with children as young as 6 years of age; however, age-specific ranges of normal recognition performance must be used.

Background: This is a case study of an 18-year-old female who suffered a bilateral idiopathic sensorineural hearing loss that was coincident with the removal of four impacted wisdom teeth. Throughout childhood the patient had normal hearing for pure tones bilaterally as measured at the pediatrician's office. One month prior to dental surgery (May) the patient volunteered to participate in an auditory experiment at which time her pure-tone audiogram was normal. Immediately following surgery (June), the patient had substantial swelling of the face and complained of some hearing loss with no other auditory/vestibular complaints. The following month (July) during the course of a routine physical examination a pure-tone audiogram revealed bilateral, air-conduction thresholds of 30-35 dB HL (500-4000 Hz) and 20 dB HL (8000 Hz). Because bone conduction was not tested, it is impossible to know whether the hearing loss was conductive, mixed, or sensorineural. The pediatrician thought that the hearing loss was conductive and would resolve as the edema subsided. A month later (August) the subject again volunteered for an auditory experiment at which time her hearing again was tested. Purpose: The purpose of this report is to detail the dental procedures involved in the extraction of the wisdom teeth, to report the results of a variety and series of post-op hearing tests, and to discuss the possible mechanisms that might be involved in the ''idiopathic'' bilateral sensorineural hearing loss. Research Design: Case report. Results: During the August visit to the laboratory, hearing for pure tones bilaterally was 0 to 5 dB HL at 250-1000 Hz with a 40-45 dB HL notch at 2000 Hz with a return to 10 dB HL at 8000 Hz. Air conduction and bone conduction thresholds were equivalent. Word recognition in quiet was ≥92 percent correct for both ears, whereas the signal-to-noise ratio (SNR) hearing loss measured with the Words-in-Noise test was high normal in the left ear with a mild SNR hearing loss in the right ear. Tympanometry and acoustic reflex thresholds were normal. Distortion product otoacoustic emissions were reduced in the 1000-3000 Hz region for both ears, which is consistent with cochlear hearing loss. The hearing loss has remained unchanged for the past 19 months. Conclusions: The possible etiologies, including insults to the cochleae by vibration trauma and through alterations in the blood supply to the cochleae, are considered.

Retest stability and retest reliability were assessed for the Words-in-Noise Test (WIN) in two experiments involving older listeners with sensorineural hearing loss. In Experiment 1, the 70-item WIN protocol was administered during two sessions 12 months apart to examine retest stability on a sample of 315 veterans from four VA Medical Centers. The mean 50% points on the WIN were 12.5- and 12.8-dB S/N for the two sessions with a critical difference of 3.5 dB and an intra-class correlation coefficient of 0.88. [Normal recognition performance on the WIN (50% point) is ≤6-dB S/N.] In Experiment 2, intra- and inter-session retest reliability was examined for the two 35-word WIN protocols on 96 veterans, 48 of whom had mild-to-severe hearing loss (Group 1) and 48 of whom had a moderate-to-severe hearing loss (Group 2). The mean 50% points on the WIN during the two sessions (separated by 40 days) were 13.0- and 13.4-dB S/N (Group 1) and 15.3- and 15.8-dB S/N (Group 2) with no significant intra-session differences. A 3.1-dB critical difference was calculated for the groups combined with intraclass correlations of 0.89 and 0.91 for Group 1 and Group 2, respectively.

The Words-in-Noise (WIN) test uses monosyllabic words in seven signal-to-noise ratios of multitalker babble (MTB) to evaluate the ability of individuals to understand speech in background noise. The purpose of this study was to evaluate the criterion validity of the WIN by comparing recognition performances under MTB and speech-spectrum noise (SSN) using listeners with normal hearing and listeners with hearing loss. The MTB and SSN had identical rms and similar spectra but different amplitude-modulation characteristics. The performances by the listeners with normal hearing, which were 2 dB better in MTB than in SSN, were about 10 dB better than the performances by the listeners with hearing loss, which were about 0.5 dB better in MTB with 56% of the listeners better in MTB and 40% better in SSN. The slopes of the functions for the normal-hearing listeners (8-9%/dB) were steeper than the functions for the listeners with hearing loss (5-6%/dB). The data indicate that the WIN has good criterion validity.

In an initial experiment (Wilson and Weakley, 2004), word recognition was assessed with six digit triplets presented at 14 signal-to-babble ratios (S/B) in 2 dB steps. An abbreviated version of the protocol was developed for clinic use involving three digit triplets at 7 S/Bs in 4 dB steps. The purpose of this experiment was to examine the relationship between the two digit protocols with comparisons made with other variables including age, pure-tone thresholds, subjective measures of understanding speech in quiet and in noise, and word recognition of monosyllabic words in quiet and in babble. Ninety-six listeners with sensorineural hearing loss participated. For equivalent performance, the short version of the digit triplets required (1) a 2.6 dB more favorable S/B than the long version and (2) a 15.1 dB less favorable S/B than the words. Age, hearing loss, and subjective evaluation of the ability to understand speech in quiet and in noise were not related to performance on digits or words in multitalker babble.

Background: Two previous experiments from our laboratory with 70 interrupted monosyllabic words demonstrated that recognition performance was influenced by the temporal location of the interruption pattern. The interruption pattern (10 interruptions/sec, 50% duty cycle) was always the same and referenced word onset; the only difference between the patterns was the temporal location of the onand off-segments of the interruption cycle. In the first study, both young and older listeners obtained better recognition performances when the initial on-segment coincided with word onset than when the initial on-segment was delayed by 50 msec. The second experiment with 24 young listeners detailed recognition performance as the interruption pattern was incremented in 10-msec steps through the 0-To 90-msec onset range. Across the onset conditions, 95% of the functions were either flat or U-shaped. Purpose: To define the effects that interruption pattern locations had on word recognition by older listeners with sensorineural hearing loss as the interruption pattern incremented, re: Word onset, from 0 to 90 msec in 10-msec steps. Research Design: A repeated-measures design with ten interruption patterns (onset conditions) and one uninterruption condition. Study Sample: Twenty-four older males (mean = 69.6 yr) with sensorineural hearing loss participated in two 1-hour sessions. The three-frequency pure-Tone average was 24.0 dB HL and word recognition was $80% correct. Data Collection and Analyses: Seventy consonant-vowel nucleus-consonant words formed the corpus of materials with 25 additional words used for practice. For each participant, the 700 interrupted stimuli (70 words by 10 onset conditions), the 70 words uninterrupted, and two practice lists each were randomized and recorded on compact disc in 33 tracks of 25 words each. Results: The data were analyzed at the participant and word levels and compared to the results obtained earlier on 24 young listeners with normal hearing. The mean recognition performance on the 70 words uninterrupted was 91.0% with an overallmean performance on the ten interruption conditions of 63.2% (range: 57.9-69.3%), compared to 80.4% (range: 73.0-87.7%) obtained earlier on the young adults. The best performances were at the extremes of the onset conditions. Standard deviations ranged from 22.1% to 28.1% (24 participants) and from 9.2% to 12.8% (70 words). An arithmetic algorithm categorized the shapes of the psychometric functions across the ten onset conditions.With the older participants in the current study, 40% of the functions were flat, 41.4% were U-shaped, and 18.6% were inverted U-shaped, which compared favorably to the function shapes by the young listeners in the earlier study of 50.0%, 41.4%, and 8.6%, respectively. There were two words on which the older listeners had 40% better performances. Conclusion: Collectively, the data are orderly, but at the individual word or participant level, the data are somewhat volatile, which may reflect auditory processing differences between the participant groups. The diversity of recognition performances by the older listeners on the ten interruption conditions with each of the 70 words supports the notion that the term hearing loss is inclusive of processes well beyond the filtering produced by end-organ sensitivity deficits.

Auditory short-term memory (STM) is important for speech and language development and for learning new information presented auditorily. Research has shown that auditory STM ability is of a developmental nature in the 5 through 8 year age range for a variety of auditory stimuli. Many tests and subtests are available to measure auditory STM ability, however one test, the Auditory Memory Test Battery (AMTB) measures auditory memory span and memory for sequence for 5 types of stimuli. The purpose of this study was to collect normative data on the AMTB scores of normal 9 through 13 year old students and young adults ages 20 through 30 years. The main experimental question was: What are the means and standard deviations of the AMTB scores from samples of normal children 9 through 13 years of age and normal young adults 20 through 30 years of age. A secondary question was: Are the differences between the performance scores statistically significant?