Short-term retention of learning after rapid adaptation to native and non-native speecha).

Non-native, accented speech spoken by unfamiliar talkers can be challenging to recognize, but rapid improvements in perception are often observed after a short period of exposure. However, it is not clear whether these improvements are retained over multiple sessions. Stimulus variability facilitates learning for non-native speech, so it is possible it may also induce increased retention of learning for speech produced with an unfamiliar accent. In this paper, we conduct a retrospective analysis of a dataset well suited to examine learning of non-native English speech on both a within-session and across-session basis. During data collection, participants completed a protocol involving recognition of matrix sentences recorded by native and non-native talkers with different first languages. Listeners completed the protocol in a self-paced approach, including 15 blocks of 50 trials over 4-7 days, separated by an average of 1-2 days. Learning was strongest within the first day, and improvements were retained at subsequent test sessions. The pace of learning was faster for stimuli produced by native speakers of English as compared to non-native English speakers.

Developing an Evidence-Based Military Auditory Fitness-for-Duty Standard Based on the 80-Word Modified Rhyme Test.

OBJECTIVES: One important function of military audiology is to conduct evaluations of service members (SMs) with hearing loss to ensure they are fit for deployment in dangerous operational environments. The objective of this study was to establish evidence-based auditory fitness-for-duty criteria based on speech-in-noise performance on the 80- and 160-word clinical versions of the Modified Rhyme Test (MRT 80 and MRT 160 ). DESIGN: Approximately 2400 SMs with various levels of hearing loss were recruited to complete the MRT 80 in conjunction with their annual hearing conservation evaluations. These SMs were also asked to perform one or more operationally-relevant listening tasks based on audio recordings made in highly realistic military training environments. The scores on these tests were compared to determine how well a proposed cutoff criterion for the MRT 80 was able to identify individuals who are hard of hearing with an exceptionally high risk of abnormally poor performance on operationally-relevant hearing tasks. RESULTS: The results show that a cutoff criterion that combines the percent correct score on two lists of the MRT 80 (i.e. MRT 160 ) with information about the better-ear threshold at 2 kHz is generally able to separate listeners with hearing loss into those who are likely to perform relatively well on operational listening tests and those who are likely to perform poorly on these tasks. This is consistent with current military acquisition standards, which identify the MRT as the preferred test for evaluating speech intelligibility for radios, headsets, and other communication equipment. It is also consistent with prior studies conducted in high-fidelity military simulations which have shown a significant correlation between MRT performance and operational outcomes. CONCLUSIONS: The proposed selection criteria, along with the new hearing profile standards that were recently adopted by the US Army, appear to provide an effective evidence-based methodology for identifying those SMs with hearing loss who are most at risk for poor performance on hearing-critical military tasks.

Development of an 80-word clinical version of the modified rhyme test (MRT80).

The modified rhyme test [MRT; House, Williams, Hecker, and Kryter. (1965). J. Acoust. Soc. Am. 37, 158-166] is a widely used test for measuring the intelligibility of communication systems [ANSI (2009). S3.2 (American National Standards Institute, New York)] but has never gained widespread acceptance as a clinical test of speech intelligibility for listeners who are hearing impaired (HI). In this study, a clinical version of the MRT consisting of two 80-word lists was developed and tested on 2394 service members with varying levels of hearing loss. The test used a factorial design incorporating two speech levels [70 and 78 dB sound pressure level (SPL)], two signal-to-noise ratios (+4 and -4 dB), and two binaural conditions (diotic and binaural). High-frequency emphasis reduced the impact of audibility for HI listeners, focusing the test on the distortion component of hearing loss. The results show that listeners with normal hearing (NH) obtained an average score of 80% correct on the MRT80 test. Listeners with a moderate hearing impairment scored an average of 70% correct. The overall level had little impact on performance for either NH or HI listeners. The results demonstrate that the MRT80 test could be a useful test to assess the distortion effects of hearing loss on speech intelligibility, particularly in cases where it is desirable to use a closed-set test for automatic administration.

Predicting Speech-in-Noise Deficits from the Audiogram.

OBJECTIVES: In occupations that involve hearing critical tasks, individuals need to undergo periodic hearing screenings to ensure that they have not developed hearing losses that could impair their ability to safely and effectively perform their jobs. Most periodic hearing screenings are limited to pure-tone audiograms, but in many cases, the ability to understand speech in noisy environments may be more important to functional job performance than the ability to detect quiet sounds. The ability to use audiometric threshold data to identify individuals with poor speech-in-noise performance is of particular interest to the U.S. military, which has an ongoing responsibility to ensure that its service members (SMs) have the hearing abilities they require to accomplish their mission. This work investigates the development of optimal strategies for identifying individuals with poor speech-in-noise performance from the audiogram. DESIGN: Data from 5487 individuals were used to evaluate a range of classifiers, based exclusively on the pure-tone audiogram, for identifying individuals who have deficits in understanding speech in noise. The classifiers evaluated were based on generalized linear models (GLMs), the speech intelligibility index (SII), binary threshold criteria, and current standards used by the U.S. military. The classifiers were evaluated in a detection theoretic framework where the sensitivity and specificity of the classifiers were quantified. In addition to the performance of these classifiers for identifying individuals with deficits understanding speech in noise, data from 500,733 U.S. Army SMs were used to understand how the classifiers would affect the number of SMs being referred for additional testing. RESULTS: A classifier based on binary threshold criteria that was identified through an iterative search procedure outperformed a classifier based on the SII and ones based on GLMs with large numbers of fitted parameters. This suggests that the saturating nature of the SII is important, but that the weights of frequency channels are not optimal for identifying individuals with deficits understanding speech in noise. It is possible that a highly complicated model with many free parameters could outperform the classifiers considered here, but there was only a modest difference between the performance of a classifier based on a GLM with 26 fitted parameters and one based on a simple all-frequency pure-tone average. This suggests that the details of the audiogram are a relatively insensitive predictor of performance in speech-in-noise tasks. CONCLUSIONS: The best classifier identified in this study, which was a binary threshold classifier derived from an iterative search process, does appear to reliably outperform the current thresholds criteria used by the U.S. military to identify individuals with abnormally poor speech-in-noise performance, both in terms of fewer false alarms and a greater hit rate. Substantial improvements in the ability to detect SMs with impaired speech-in-noise performance can likely only be obtained by adding some form of speech-in-noise testing to the hearing monitoring program. While the improvements were modest, the overall benefit of adopting the proposed classifier is likely substantial given the number of SMs enrolled in U.S. military hearing conservation and readiness programs.

Clear versus casual consonant identification by hearing-impaired and normal-hearing listeners.

Hearing-impaired (HI) listeners who benefit from hearing-aid use in quiet often continue to have difficulty understanding speech in noise. Requesting talkers to speak clearly is one strategy to overcome this deficit. Paradoxically, one feature of clear speech is a shift to higher frequencies, which may move speech energy into a frequency range that is inaudible or more distorted for some HI listeners. Casual (or conversational) speech, on the other hand, may shift speech energy into a lower frequency range that is more audible or less distorted. This study examined the intelligibility of 21 amplified, casually- and clearly-spoken, US English coda consonants in nonsense syllables for 10 normal-hearing (NH) and 17 HI listeners. Most clear-speech consonants yielded higher recognition scores as expected. However, certain phonological processes common in casual speech, such as palatalization of higher frequency alveolar into lower frequency postalveolar consonants, generated significantly higher scores than their clear counterparts for some HI listeners in noise. These results have implications for coaching conversational partners of aided HI listeners. For the military, talkers can be instructed how to speak to Service members with hearing loss or in noisy environments.

Neurogenic Orofacial Weakness and Speech in Adults With Dysarthria.

PURPOSE: This study compared orofacial strength between adults with dysarthria and neurologically normal (NN) matched controls. In addition, orofacial muscle weakness was examined for potential relationships to speech impairments in adults with dysarthria. METHOD: Matched groups of 55 adults with dysarthria and 55 NN adults generated maximum pressure (Pmax) against an air-filled bulb during lingual elevation, protrusion and lateralization, and buccodental and labial compressions. These orofacial strength measures were compared with speech intelligibility, perceptual ratings of speech, articulation rate, and fast syllable-repetition rate. RESULTS: The dysarthria group demonstrated significantly lower orofacial strength than the NN group on all tasks. Lingual strength correlated moderately and buccal strength correlated weakly with most ratings of speech deficits. Speech intelligibility was not sensitive to dysarthria severity. Individuals with severely reduced anterior lingual elevation Pmax (< 18 kPa) had normal to profoundly impaired sentence intelligibility (99%-6%) and moderately to severely impaired speech (26%-94% articulatory imprecision; 33%-94% overall severity). CONCLUSIONS: Results support the presence of orofacial muscle weakness in adults with dysarthrias of varying etiologies but reinforce tenuous links between orofacial strength and speech production disorders. By examining individual data, preliminary evidence emerges to suggest that speech, but not necessarily intelligibility, is likely to be impaired when lingual weakness is severe.

The Effect of Jaw Position on Perceptual and Acoustic Characteristics of Speech.

Bite blocks are used to stabilize the jaw and to isolate tongue and lip movements from that of the mandible during speech and nonspeech activities. Ten normally speaking young adults produced sentences with an unconstrained jaw and with unilateral placement of 2-mm and 5-mm bite blocks. Six listeners rated sentences spoken without either bite block as the most natural sounding. Spectral characteristics of /s/, /ʃ/ and /t/ (sibilant frication and stop bursts) differed significantly with than without bite blocks, such that mean spectral energy decreased, and variation and skew of spectral energy increased. Spectral kurtosis did not change for the group, but 2 participants exhibited highly kurtotic /s/ spectra without a bite block that normalized with bite blocks. The second formant frequency for the high vowel /i/ was lower with bite blocks; there was no systematic difference in F2 slope for diphthongs. Segmental and suprasegmental timing of speech articulation was not affected significantly by these small bite blocks. This study provides support for using small bite blocks to isolate the tongue from the jaw without large effects on speech, but cautions that speech is likely to sound less natural than when produced with an unconstrained jaw.

Benefits of Nonlinear Frequency Compression in Adult Hearing Aid Users.

BACKGROUND: Frequency-lowering (FL) algorithms are an alternative method of providing access to high-frequency speech cues. There is currently a lack of independent research addressing: (1) what functional, measureable benefits FL provides; (2) which, if any, FL algorithm provides the maximum benefit, (3) how to clinically program algorithms, and (4) how to verify algorithm settings. PURPOSE: Two experiments were included in this study. The purpose of Experiment 1 was to (1) determine if a commercially available nonlinear frequency compression (NLFC) algorithm provides benefit as measured by improved speech recognition in noise when fit and verified using standard clinical procedures; and (2) evaluate the impact of acclimatization. The purpose of Experiment 2 was to (1) evaluate the benefit of using enhanced verification procedures to systematically determine the optimal application of a prototype NLFC algorithm, and (2) determine if the optimized prototype NLFC settings provide benefit as measured by improved speech recognition in quiet and in noise. RESEARCH DESIGN: A single-blind, within-participant repeated measures design in which participants served as their own controls. STUDY SAMPLE: Experiment 1 included 26 participants with a mean age of 68.3 yr and Experiment 2 included 37 participants with a mean age of 68.8 yr. Participants were recruited from the Audiology and Speech Pathology Center at Walter Reed National Military Medical Center in Bethesda, MD. INTERVENTION: Participants in Experiment 1 wore bilateral commercially available hearing aids fit using standard clinical procedures and clinician expertise. Participants in Experiment 2 wore a single prototype hearing aid for which FL settings were systematically examined to determine the optimum application. In each experiment, FL-On versus FL-Off settings were examined in a variety of listening situations to determine benefit and possible implications. DATA COLLECTION AND ANALYSIS: In Experiment 1, speech recognition measures using the QuickSIN and Modified Rhyme Test stimuli were obtained at initial bilateral fitting and 3-5 weeks later during a follow-up visit. In Experiment 2, Modified Rhyme Test, /sə/, /∫ə/ consonant discrimination task, and dual-task cognitive load speech recognition performance measures were conducted. Participants in Experiment 2 received four different systematic hearing aid programs during an initial visit and speech recognition data were collected over 2-3 follow-up sessions. RESULTS: Some adults with hearing loss obtained small-to-moderate benefits from implementation of FL, while others maintained performance without detriment in both experiments. There was no significant difference among FL-On settings systematically obtained in Experiment 2. There was a modest but significant age effect in listeners of both experiments that indicated older listeners (>65 yr) might benefit more on average from FL than younger listeners. In addition, there were reliable improvements in the intelligibility of the phonemes /ŋ/ and /b/ for both groups, and /ð/ for older listeners from the FL in both experiments. CONCLUSIONS: Although the optimum settings, application, and benefits of FL remain unclear at this time, there does not seem to be degradation in listener performance when FL is activated. The benefits of FL should be explored in older adult (>65 yr) listeners, as they tended to benefit more from FL applications.

Speech-related fatigue and fatigability in Parkinson's disease.

This study tested the assumption that speech is more susceptible to fatigue than normal in persons with dysarthria. After 1 h of speech-like exercises, participants with Parkinson's disease (PD) were expected to report increased perceptions of fatigue and demonstrate fatigability by producing less precise speech with corresponding acoustic changes compared to neurologically normal participants. Twelve adults with idiopathic PD and 13 neurologically normal adults produced sentences with multiple lingual targets before and after six 10-min blocks of fast syllable or word productions. Both groups reported increasing self-perceived fatigue over time, but trained listeners failed to detect systematic differences in articulatory precision or speech naturalness between sentences produced before and after speech-related exercises. Similarly, few systematic acoustic differences occurred. These findings do not support the hypothesis that dysarthric speakers are particularly susceptible to speech-related fatigue; instead, speech articulation generally appears to be resistant to fatigue induced by an hour of moderate functional exercises.

Suprathreshold auditory processing and speech perception in noise: hearing-impaired and normal-hearing listeners.

BACKGROUND: It is widely believed that suprathreshold distortions in auditory processing contribute to the speech recognition deficits experienced by hearing-impaired (HI) listeners in noise. Damage to outer hair cells and attendant reductions in peripheral compression and frequency selectivity may contribute to these deficits. In addition, reduced access to temporal fine structure (TFS) information in the speech waveform may play a role. PURPOSE: To examine how measures of peripheral compression, frequency selectivity, and TFS sensitivity relate to speech recognition performance by HI listeners. To determine whether distortions in processing reflected by these psychoacoustic measures are more closely associated with speech deficits in steady-state or modulated noise. RESEARCH DESIGN: Normal-hearing (NH) and HI listeners were tested on tasks examining frequency selectivity (notched-noise task), peripheral compression (temporal masking curve task), and sensitivity to TFS information (frequency modulation [FM] detection task) in the presence of random amplitude modulation. Performance was tested at 500, 1000, 2000, and 4000 Hz at several presentation levels. The same listeners were tested on sentence recognition in steady-state and modulated noise at several signal-to-noise ratios. STUDY SAMPLE: Ten NH and 18 HI listeners were tested. NH listeners ranged in age from 36 to 80 yr (M = 57.6). For HI listeners, ages ranged from 58 to 87 yr (M = 71.8). RESULTS: Scores on the FM detection task at 1 and 2 kHz were significantly correlated with speech scores in both noise conditions. Frequency selectivity and compression measures were not as clearly associated with speech performance. Speech Intelligibility Index (SII) analyses indicated only small differences in speech audibility across subjects for each signal-to-noise ratio (SNR) condition that would predict differences in speech scores no greater than 10% at a given SNR. Actual speech scores varied by as much as 80% across subjects. CONCLUSIONS: The results suggest that distorted processing of audible speech cues was a primary factor accounting for differences in speech scores across subjects and that reduced ability to use TFS cues may be an important component of this distortion. The influence of TFS cues on speech scores was comparable in steady-state and modulated noise. Speech recognition was not related to audibility, represented by the SII, once high-frequency sensitivity differences across subjects (beginning at 5 kHz) were removed statistically. This might indicate that high-frequency hearing loss is associated with distortions in processing in lower-frequency regions.

Aerodynamic evaluation of the postthyroidectomy voice.

OBJECTIVES/HYPOTHESES: Changes in vocal function before and after thyroidectomy were examined using aerodynamic and related assessments. Laryngeal airway resistance (R(law)) and phonation threshold pressure (PTP) were hypothesized to be sensitive to changes in laryngeal function that may occur after thyroidectomy separate from changes that may occur from endotracheal intubation alone. STUDY DESIGN: Prospective longitudinal clinical trial with comparison group. METHODS: Eighty patients were evaluated preoperatively, and 2 weeks and 3 months postoperatively to assess voice outcomes after thyroidectomy. In addition, 16 patients who underwent a nonneck operation were tested as a control group. Maximum phonation time (MPT), mean airflow, R(law), and PTP were determined at two vocal fundamental frequency (F0) levels (30% and 80% of the F0 range). RESULTS: No systematic differences were detected for MPT, mean airflow, or R(law) as a short-term or intermediate-term outcome of either surgical group. PTP decreased significantly over time for both groups of participants and at both F0 levels. F0 range decreased significantly at the short-term postsurgical assessment and covaried with the PTP results, thereby explaining some of the variability in the PTP data. CONCLUSIONS: Aerodynamic assessment did not reveal systematic changes in vocal function associated with thyroidectomy, although PTP decreased postoperatively for both surgical groups. This may be attributable in part to a learning effect or to postoperative reductions in F0 range.

Medical comorbidities for paradoxical vocal fold motion (vocal cord dysfunction) in the military population.

OBJECTIVES/HYPOTHESES: This study aimed to describe the demographic characteristics of patients diagnosed with paradoxical vocal fold motion (PVFM) at Walter Reed Army Medical Center (WRAMC), and to document common medical comorbidities. The military population was expected to differ from the general population because of a presumed association between high physical demands and PVFM. STUDY DESIGN: Retrospective chart review of active-duty (AD) military personnel compared with a natural control group of non-AD patients. METHODS: Reports of asthma, allergy, gastroesophageal reflux disease (GERD), and postnasal drip (consequent to chronic sinusitis) were recorded for patients referred to the Speech Pathology Clinic at WRAMC with a diagnosis of PVFM from 1996 to 2001. RESULTS: The cohort consisted of 265 patients, 127 of whom were on AD status. The AD group was significantly younger and represented a narrower age range (17-53 years) than the non-AD patients (8-80 years), and had a more balanced sex ratio (1.2:1 vs 2.9:1). Eighty percent of all patients had at least one of the medical comorbidities surveyed, and 51% had two or more factors. GERD and allergies were reported most commonly by both groups; only asthma occurred significantly more in non-AD than AD patients. CONCLUSIONS: PVFM referrals of AD personnel of the US military are characterized by younger patients and a smaller female:male ratio as compared with non-AD patients. Based on the preponderance of men in the military, the number of females in the AD group remained disproportionately large. Multiple medical comorbidities were commonly documented by both groups; the only significant difference was a greater prevalence of asthma in the non-AD group. These data reinforce the need for appropriate differential diagnosis in all patients.

Prospective trial of voice outcomes after thyroidectomy: evaluation of patient-reported and clinician-determined voice assessments in identifying postthyroidectomy dysphonia.

BACKGROUND: Reliable voice grading systems to identify postoperative voice dysfunction by surgeons are needed. PURPOSE: To examine the utility of patient-reported and clinician-determined voice assessment in identifying postthyroidectomy voice dysfunction. PATIENTS AND METHODS: Fifty patients enrolled in a prospective observational trial evaluating voice function perioperatively by patient-reported symptoms (Voice Case History [VCHx]) and perceived voice handicap (Voice Handicap Index [VHI]), clinician-determined judgment of voice quality (Consensus Auditory-Perceptual Evaluation--Voice [CAPE-V]), and laryngeal examination via video laryngoscopy (VLS). Voice dysfunction at first postoperative visit in symptomatic patients was defined by objective laryngeal abnormalities on VLS. Postoperative changes from baseline in voice parameters were compared between patients with and without voice dysfunction using the Wilcoxon rank sum test. Receiver operating characteristics were evaluated to determine area under the curve (AUC) for tested parameters. RESULTS: Eight (16%) had early transient and 1 (2%) had permanent postoperative voice dysfunction. VCHx symptoms had negative (NPV) and positive (PPV) predictive values of 96%-100% and 39%-53%, respectively for voice dysfunction. The rating of overall severity from the CAPE-V was highly predictive (AUC = 0.96), and a change in severity from preoperative baseline >or=20% at 1-2 weeks had a PPV of 86% and NPV of 95% for postoperative dysphonia. Patient-reported total VHI score was most predictive (AUC = 0.97) and a change in VHI from preoperative baseline >or=25 early postoperatively had a PPV of 88% and NPV of 97% for postoperative dysphonia. CONCLUSION: Patient self-assessment of voice handicap using the VHI reliably identifies voice dysfunction after thyroidectomy. Patients with a change in VHI >or=25 from preoperative baseline warrant early referral to speech pathology and laryngology.

Assessment of Orofacial Strength in Patients with Dysarthria.

Assessment of orofacial weakness is common during the evaluation of patients with suspected dysarthria. This study addressed the validity of clinical assessments of orofacial weakness by comparing clinical (subjective) ratings to instrumental (objective) measures. Forty-four adults referred to a speech pathology clinic for dysarthria evaluation were tested for strength of the tongue during elevation, lateralization, and protrusion, and for the strength of the muscles of the lower face during buccodental and interlabial compression. Subjective assessment of weakness involved rating maximum resistance against a firmly held tongue depressor, using a 5-point scale. Objective assessment involved the Iowa Oral Performance Instrument (IOPI), measured as the maximal pressure generated against an air-filled bulb. A recent adaptation to the IOPI permitted testing of tongue and cheek strength using tasks that are comparable to the subjective tasks. Moderate correlations were found between the objective and subjective evaluations, with the strongest correlations for tongue lateralization. Lower pressure values were associated with higher subjective ratings of weakness for each task, although there was substantial overlap in the data. These results, combined with the notion that examiner bias is inherent to clinical assessment, support the use of instrumentation to improve objectivity and precision of measurement in the clinic.

Phonation threshold pressure across the pitch range: preliminary test of a model.

This study sought to examine the specific relationship between phonation threshold pressure (PTP) and voice fundamental frequency (F(0)) across the pitch range. A published theoretical model of this relationship described a quadratic equation, with PTP increasing exponentially with F(0). Prospective data from eight adults with normal, untrained voices were collected. Subjects produced their quietest phonation at 10 randomly ordered pitches from 5% to 95% of their semitone pitch range at 10% intervals. Analysis included curve fitting for individual and group data, as well as comparisons to the previous model. The group data fit a quadratic function similar to that proposed previously, but the specific quadratic coefficient and constant values differed. Four of the individual subjects' data were best fit by quartic functions, two by quadratic functions, and one by a linear function. This preliminary study indicates that PTP may be minimal at a "comfortable" pitch rather than the lowest pitch tested, and that, for some individuals, PTP may be slightly elevated during the passaggio between modal and falsetto vocal registers. These data support the general form of the theoretical PTP-F(0) function for these speakers, and indicate the possibility of potential refinements to the model. Future studies with larger groups of male and female subjects across a wider age range may eventually reveal the specific nature of the function.

Speech-Breathing Treatment and LSVT for a Patient With Hypokinetic-Spastic Dysarthria After TBI.

Previously, we reported improved speech breathing and intelligibility after behavioral treatment for a man with hypokinetic-spastic dysarthria following traumatic brain injury (TBI) (Solomon, McKee, & Garcia-Barry, 2001). Treatment included the Lee Silverman Voice Treatment® (LSVT) program followed by 6 weeks of speech-breathing training, physical therapy, and LSVT-type tasks. In this article, we report a new patient with similar speech characteristics post-TBI. Breathing-for-Speech Treatment (BST), custom designed to improve nonspeech- and speech-breathing coordination, was followed by LSVT. After BST, speech breathing approached normal levels; after LSVT, speech breathing improved further and intelligibility improved markedly. Gains generally were maintained up to 4 months, but were limited by the spastic characteristics of his dysarthria and sporadic medical complications.