Intensity Resolution in Individuals With Parkinson's Disease: Sensory and Auditory Memory Limitations.

Purpose The purpose of the current study was to examine sensory and auditory memory limitations on intensity resolution in individuals with Parkinson's disease as compared to healthy older and younger adults. Method Nineteen individuals with Parkinson's disease, 10 healthy age- and hearing-matched adults, and 10 healthy young adults were studied. The listeners participated in 2 intensity discrimination tasks: a lower memory load 4IAX task (sensory limitations) and a higher memory load ABX task (auditory memory limitations). Intensity resolution was examined across groups and tasks using a bias-free measurement of signal detectability known as d' (d-prime). Listeners also participated in a loudness scaling task where they were instructed to rate the loudness level of each signal intensity along the experimental continuum using a computerized 150-mm visual analog scale. Results Intensity discrimination sensitivity (d') was significantly poorer in the 4IAX and ABX conditions for the individuals with Parkinson's disease, as compared to the older and younger controls. Furthermore, a significant age-related difference was identified for the loudness scaling condition. The younger controls rated most stimuli along the experimental continuum significantly louder as compared to the older controls and the individuals with Parkinson's disease. Conclusions The present discrimination data suggest sensory and auditory memory limitations may contribute to the intensity resolution issues associated with Parkinson's disease. Age-related differences in loudness scaling will be reviewed.

Discrimination and Identification of a Third Formant Frequency Cue to Place of Articulation by Young Children and Adults.

Typically-developing children, 4 to 6 years of age, and adults participated in discrimination and identification speech perception tasks using a synthetic consonant-vowel continuum ranging from /da/ to /ga/. The seven-step synthetic /da/-/ga/ continuum was created by adjusting the first 40 ms of the third formant frequency transition. For the discrimination task, listeners participated in a Change/No-Change paradigm with four different stimuli compared to the endpoint-1 /da/ token. For the identification task, listeners labeled each token along the /da/-/ga/ continuum as either "DA" or "GA." Results of the discrimination experiment showed that sensitivity to the third-formant transition cue improved for the adult listeners as the stimulus contrast increased, whereas the performance of the children remained poor across all stimulus comparisons. Results of the identification experiment support previous hypotheses of age-related differences in phonetic categorization. Results have implications for normative data on identification and discrimination tasks. These norms provide a metric against which children with auditory-based speech sound disorders can be compared. Furthermore, the results provide some insight into the developmental nature of categorical and non-categorical speech perception.

Laryngeal Aerodynamics in Healthy Older Adults and Adults With Parkinson's Disease.

Purpose: The present study compared laryngeal aerodynamic function of healthy older adults (HOA) to adults with Parkinson's disease (PD) while speaking at a comfortable and increased vocal intensity. Method: Laryngeal aerodynamic measures (subglottal pressure, peak-to-peak flow, minimum flow, and open quotient [OQ]) were compared between HOAs and individuals with PD who had a diagnosis of hypophonia. Increased vocal intensity was elicited via monaurally presented multitalker background noise. Results: At a comfortable speaking intensity, HOAs and individuals with PD produced comparable vocal intensity, rates of vocal fold closure, and minimum flow. HOAs used smaller OQs, higher subglottal pressure, and lower peak-to-peak flow than individuals with PD. Both groups increased speaking intensity when speaking in noise to the same degree. However, HOAs produced increased intensity with greater driving pressure, faster vocal fold closure rates, and smaller OQs than individuals with PD. Conclusions: Monaural background noise elicited equivalent vocal intensity increases in HOAs and individuals with PD. Although both groups used laryngeal mechanisms as expected to increase sound pressure level, they used these mechanisms to different degrees. The HOAs appeared to have better control of the laryngeal mechanism to make changes to their vocal intensity.

The effect of increased vocal intensity on interarticulator timing in speakers with Parkinson's disease: a preliminary analysis.

PURPOSE: The purpose of the current study was to investigate the effect of increased vocal intensity on interarticulator timing in individuals with Parkinson's disease (PD). METHODS: Ten individuals with mild to moderate hypophonia, secondary to PD, were selected for study. Over an 8-week treatment period, multi-talker babble noise was presented monaurally to the individuals with PD during everyday communication contexts to elicit increased vocal intensity (Lombard effect). Outcome measures included sound pressure level (SPL), voice onset time (VOT), VOT ratio, percent voicing, and speech intelligibility. RESULTS: Group and individual participant responses to the treatment are reported and discussed. Speakers with PD were shown to significantly increase SPL in response to treatment. Six of the 10 speakers showed improved temporal coordination between the laryngeal and supralaryngeal mechanisms (interarticulator timing) in response to treatment. Four of the 10 speakers, however, showed reduced laryngeal­supralaryngeal timing at the end of treatment. Group speech intelligibility scores were significantly higher post-treatment as compared to pre-treatment. CONCLUSIONS: Voice treatment during everyday communication resulted in improved temporal coordination across the laryngeal and supralaryngeal mechanisms for the majority of speakers with PD and made them easier to understand. Further investigations are planned to explore individual differences in response to treatment. The identification of speaker-specific voicing and devoicing strategies is consistent with the heterogeneous nature of PD. LEARNING OUTCOMES: Readers will be able to: 1. Describe the speech and voice characteristics of individuals with Parkinson's disease. 2. Define the Lombard effect. 3. Describe acoustic measures of voice onset time and percent voicing. 4. Describe the effect of voice treatment on voice onset time and percent voicing in individuals with Parkinson's disease.

Acoustic and perceptual correlates of faster-than-habitual speech produced by speakers with Parkinson's disease and multiple sclerosis.

UNLABELLED: Acoustic-perceptual characteristics of a faster-than-habitual rate (Fast condition) were examined for speakers with Parkinson's disease (PD) and multiple sclerosis (MS). Judgments of intelligibility for sentences produced at a habitual rate (Habitual condition) and at a faster-than-habitual rate (Fast condition) by 46 speakers with PD or MS as well as a group of 32 healthy speakers revealed that the Fast condition was, on average, associated with decreased intelligibility. However, some speakers' intelligibility did not decline. To further understand the acoustic characteristics of varied intelligibility in the Fast condition for speakers with dysarthria, a subgroup of speakers with PD or MS whose intelligibility did not decline in the Fast condition (no decline group, n=8) and a subgroup of speakers with significantly declined intelligibility (decline group, n=8) were compared. Acoustic measures of global speech timing, suprasegmental characteristics, and utterance-level segmental characteristics for vocalics were examined for the two subgroups. Results suggest acoustic contributions to intelligibility under rate modulation are complex. Potential clinical relevance and implications for the acoustic bases of intelligibility are discussed. LEARNING OUTCOMES: Readers will be able to (1) discuss existing evidence for the use of rate change to facilitate intelligibility, (2) describe acoustic-perceptual characteristics of a faster-than-habitual rate among speakers with mild dysarthria, (3) discuss the relationships between rate, intelligibility, suprasegmental variables, and segmental variables, (4) identify the need to further investigate the acoustic basis for intelligibility and its potential theoretical and clinical implications.

Impact of clear, loud, and slow speech on scaled intelligibility and speech severity in Parkinson's disease and multiple sclerosis.

PURPOSE: The perceptual consequences of rate reduction, increased vocal intensity, and clear speech were studied in speakers with multiple sclerosis (MS), Parkinson's disease (PD), and healthy controls. METHOD: Seventy-eight speakers read sentences in habitual, clear, loud, and slow conditions. Sentences were equated for peak amplitude and mixed with multitalker babble for presentation to listeners. Using a computerized visual analog scale, listeners judged intelligibility or speech severity as operationally defined in Sussman and Tjaden (2012). RESULTS: Loud and clear but not slow conditions improved intelligibility relative to the habitual condition. With the exception of the loud condition for the PD group, speech severity did not improve above habitual and was reduced relative to habitual in some instances. Intelligibility and speech severity were strongly related, but relationships for disordered speakers were weaker in clear and slow conditions versus habitual. CONCLUSIONS: Both clear and loud speech show promise for improving intelligibility and maintaining or improving speech severity in multitalker babble for speakers with mild dysarthria secondary to MS or PD, at least as these perceptual constructs were defined and measured in this study. Although scaled intelligibility and speech severity overlap, the metrics further appear to have some separate value in documenting treatment-related speech changes.

Increased vocal intensity due to the Lombard effect in speakers with Parkinson's disease: simultaneous laryngeal and respiratory strategies.

PURPOSE: The objective of the present study was to investigate whether speakers with hypophonia, secondary to Parkinson's disease (PD), would increases their vocal intensity when speaking in a noisy environment (Lombard effect). The other objective was to examine the underlying laryngeal and respiratory strategies used to increase vocal intensity. METHODS: Thirty-three participants with PD were included for study. Each participant was fitted with the SpeechVive™ device that played multi-talker babble noise into one ear during speech. Using acoustic, aerodynamic and respiratory kinematic techniques, the simultaneous laryngeal and respiratory mechanisms used to regulate vocal intensity were examined. RESULTS: Significant group results showed that most speakers with PD (26/33) were successful at increasing their vocal intensity when speaking in the condition of multi-talker babble noise. They were able to support their increased vocal intensity and subglottal pressure with combined strategies from both the laryngeal and respiratory mechanisms. Individual speaker analysis indicated that the particular laryngeal and respiratory interactions differed among speakers. CONCLUSIONS: The SpeechVive™ device elicited higher vocal intensities from patients with PD. Speakers used different combinations of laryngeal and respiratory physiologic mechanisms to increase vocal intensity, thus suggesting that disease process does not uniformly affect the speech subsystems. LEARNING OUTCOMES: Readers will be able to: (1) identify speech characteristics of people with Parkinson's disease (PD), (2) identify typical respiratory strategies for increasing sound pressure level (SPL), (3) identify typical laryngeal strategies for increasing SPL, (4) define the Lombard effect.

Functional anatomy of the masking level difference, an fMRI study.

INTRODUCTION: Masking level differences (MLDs) are differences in the hearing threshold for the detection of a signal presented in a noise background, where either the phase of the signal or noise is reversed between ears. We use N0/Nπ to denote noise presented in-phase/out-of-phase between ears and S0/Sπ to denote a 500 Hz sine wave signal as in/out-of-phase. Signal detection level for the noise/signal combinations N0Sπ and NπS0 is typically 10-20 dB better than for N0S0. All combinations have the same spectrum, level, and duration of both the signal and the noise. METHODS: Ten participants (5 female), age: 22-43, with N0Sπ-N0S0 MLDs greater than 10 dB, were imaged using a sparse BOLD fMRI sequence, with a 9 second gap (1 second quiet preceding stimuli). Band-pass (400-600 Hz) noise and an enveloped signal (.25 second tone burst, 50% duty-cycle) were used to create the stimuli. Brain maps of statistically significant regions were formed from a second-level analysis using SPM5. RESULTS: The contrast NπS0- N0Sπ had significant regions of activation in the right pulvinar, corpus callosum, and insula bilaterally. The left inferior frontal gyrus had significant activation for contrasts N0Sπ-N0S0 and NπS0-N0S0. The contrast N0S0-N0Sπ revealed a region in the right insula, and the contrast N0S0-NπS0 had a region of significance in the left insula. CONCLUSION: Our results extend the view that the thalamus acts as a gating mechanism to enable dichotic listening, and suggest that MLD processing is accomplished through thalamic communication with the insula, which communicate across the corpus callosum to either enhance or diminish the binaural signal (depending on the MLD condition). The audibility improvement of the signal with both MLD conditions is likely reflected by activation in the left inferior frontal gyrus, a late stage in the what/where model of auditory processing.

Perceptual measures of speech from individuals with Parkinson's disease and multiple sclerosis: intelligibility and beyond.

PURPOSE: The primary purpose of this study was to compare percent correct word and sentence intelligibility scores for individuals with multiple sclerosis (MS) and Parkinson's disease (PD) with scaled estimates of speech severity obtained for a reading passage. METHOD: Speech samples for 78 talkers were judged, including 30 speakers with MS, 16 speakers with PD, and 32 healthy control speakers. Fifty-two naive listeners performed forced-choice word identification, sentence transcription, or visual analog scaling of speech severity for the Grandfather Passage (Duffy, 2005). Three expert listeners also scaled speech severity for the Grandfather Passage. RESULTS: Percent correct word and sentence intelligibility scores did not cleanly differentiate speakers with MS, PD, or control speakers. In contrast, both naive and expert listener groups judged reading passages produced by speakers with MS and PD to be more severely impaired than reading passages produced by control talkers. CONCLUSION: Scaled estimates of speech severity appear to be sensitive to aspects of speech impairment in MS and PD not captured by word or sentence intelligibility scores. One implication is that scaled estimates of speech severity might prove useful for documenting speech changes related to disease progression or even treatment for individuals with MS and PD with minimal reduction in intelligibility.

Changes in acoustic characteristics of the voice across the life span: measures from individuals 4-93 years of age.

PURPOSE: The purpose of the present investigation was to examine acoustic voice changes across the life span. Previous voice production investigations used small numbers of participants, had limited age ranges, and produced contradictory results. METHOD: Voice recordings were made from 192 male and female participants 4-93 years of age. Acoustic measures of fundamental frequency (F0), sound pressure level (SPL), and signal-to-noise ratio (SNR) were made. Coefficients of variation for F0, SPL, and SNR served as measures of variability. Variables were analyzed separately with stepwise regressions, using age and sex as predictors. RESULTS: Differences in F0 and SNR across the life span were sex specific. Male and female participants demonstrated significant nonlinear trends for F0, but the trends were stronger for male participants. Female participants demonstrated a similar nonlinear trend for SNR, whereas male participants demonstrated linear increases in SNR with age. Variability of F0, SPL, and SNR followed nonlinear trends, higher at younger and older ages. CONCLUSIONS: Changes in voice production occur throughout the life span, often in a nonlinear way and differently for male and female individuals. Higher variability of acoustic measures of voice in both young and old speakers reflects changes in anatomic structure, physiologic mechanisms, and motor control.

Long-Term Average Spectral (LTAS) Measures of Dysarthria and Their Relationship to Perceived Severity.

This study investigated the relationship between measures of Long-Term Average Spectrum (LTAS) for speakers with Parkinson's disease (PD) and Multiple Sclerosis (MS) and scaled estimates of perceived speech severity. Perceived severity was operationally defined as listeners' overall impression of voice, resonance, articulatory precision, and prosody without regard to intelligibility. Healthy control talkers were also studied. Speakers were audio recorded while reading Harvard Sentences and the Grandfather Passage. Using TF32 (Milenkovic, 2005), the LTAS was computed for sentences. Coefficients of the first four moments were used to characterize energy across the speech spectrum. Supplemental acoustic measures of articulatory rate, vocal intensity, and fundamental frequency also were obtained. Three speech-language pathologists scaled speech severity for the reading passages. Results indicated no group differences in acoustic measures. The absolute magnitude of correlations between LTAS moment coefficients and perceptual estimates of scaled severity within and across speaker groups ranged from .16 to .53, with the strongest correlations for the PD group. These results suggest that the LTAS may prove useful in conjunction with perceptual judgments to document speech spectral changes related to treatment or disease progression. Findings further suggest that different acoustic models of severity are likely needed for dysarthria secondary to PD and dysarthria secondary to MS.

Auditory preferences of young children with and without hearing loss for meaningful auditory-visual compound stimuli.

UNLABELLED: Experiment 1 examined modality preferences in children and adults with normal hearing to combined auditory-visual stimuli. Experiment 2 compared modality preferences in children using cochlear implants participating in an auditory emphasized therapy approach to the children with normal hearing from Experiment 1. A second objective in both experiments was to evaluate the role of familiarity in these preferences. Participants were exposed to randomized blocks of photographs and sounds of ten familiar and ten unfamiliar animals in auditory-only, visual-only and auditory-visual trials. Results indicated an overall auditory preference in children, regardless of hearing status, and a visual preference in adults. Familiarity only affected modality preferences in adults who showed a strong visual preference to unfamiliar stimuli only. The similar degree of auditory responses in children with hearing loss to those from children with normal hearing is an original finding and lends support to an auditory emphasis for habilitation. LEARNING OUTCOMES: Readers will be able to (1) Describe the pattern of modality preferences reported in young children without hearing loss; (2) Recognize that differences in communication mode may affect modality preferences in young children with hearing loss; and (3) Understand the role of familiarity in modality preferences in children with and without hearing loss.

Multi-site phasic neural activity mediates the execution of an auditory continuous performance task: a PET and electrophysiological study.

BACKGROUND AND PURPOSE: We studied an auditory continuous performance task with positron emission tomography(PET) and EEG-derived current density reconstructions (CDRs) to define the spatial and temporal aspects of auditory attention. METHODS: The CDRs were employed to segregate responses to targets and non-targets at sites identified by PET. We then studied the time course of brain activity using statistical parametric mapping (SPM) of the CDR data. RESULTS: In contrast to target EEG activity, non-targets did not produce significant peaks after 300 ms. Pre-300 ms biphasic activation of auditory, left posterior frontal, left supplemental,and primary motor cortices and the anterior cingulate (AC) and biphasic suppression of posterior cingulate and occipital cortex were identical for targets and non-targets and may mediate the target non-target decision. SPM analysis of post-300 ms CDRs showed cingulate cortices were the first to be reactivated, remained active through 672 ms, and were accompanied by reactivation and deactivation of the same sites observed in the pre-P300 responses. CONCLUSIONS: The cingulate may play an important role in post-decisional activity and control activity at other sites involved in post-decisional cognitive processing.

Multi-site phasic neural activity mediates the execution of an auditory continuous performance task: a PET and electrophysiological study.

BACKGROUND AND PURPOSE: We studied an auditory continuous performance task with positron emission tomography (PET) and EEG-derived current density reconstructions (CDRs) to define the spatial and temporal aspects of auditory attention. METHODS: The CDRs were employed to segregate responses to targets and non-targets at sites identified by PET. We then studied the time course of brain activity using statistical parametric mapping (SPM) of the CDR data. RESULTS: In contrast to target EEG activity, non-targets did not produce significant peaks after 300 ms. Pre-300 ms biphasic activation of auditory, left posterior frontal, left supplemental, and primary motor cortices and the anterior cingulate (AC) and biphasic suppression of posterior cingulate and occipital cortex were identical for targets and non-targets and may mediate the target non-target decision. SPM analysis of post-300 ms CDRs showed cingulate cortices were the first to be reactivated, remained active through 672 ms, and were accompanied by reactivation and deactivation of the same sites observed in the pre-P300 responses. CONCLUSIONS: The cingulate may play an important role in post-decisional activity and control activity at other sites involved in post-decisional cognitive processing.

Perceptual evaluation of hypernasality compared to HONC measures: the role of experience.

OBJECTIVES: Nasality ratings from experienced and inexperienced listeners were compared to accelerometric measures using the Horii Oral Nasal Coupling (HONC) Index to determine if one group's ratings are more closely related to the HONC Index measures. The reliability of listener ratings was studied to determine if experienced listeners had better reliability than inexperienced listeners. The influence of phonetic content was analyzed to learn if ratings of sentences with stop consonants yielded higher correlations with HONC scores than sentences containing glides. DESIGN: Experienced and inexperienced listeners' ratings of hypernasality were correlated to the HONC measures for two nonnasal sentence productions. Analysis of variance compared experienced versus inexperienced listener ratings. PARTICIPANTS: Ten listeners who were speech-language pathologists with at least 10 years of experience in assessing hypernasality and 10 listeners who were graduate students in communicative disorders with less than 1 year of experience. Speech samples were acquired from 13 children with varying degrees of hypernasality and 5 children with normal nasality. RESULTS: Correlations between ratings of hypernasality and HONC scores were .60 for the experienced group and .52 for the inexperienced group. In general, the experienced listeners rated the hypernasality of the speakers as less severe. Both groups had similar intrajudge reliability. Hypernasality ratings were not influenced by sentence context. CONCLUSIONS: Hypernasality can be rated in a reliable fashion regardless of listener experience. The correlations between the objective measure of nasalization (HONC) and the perceptual ratings were not as high as expected. Factors contributing to obtaining only moderate correlations will be discussed.

The control of aerodynamics, acoustics, and perceptual characteristics during speech production.

One of the most important areas of study in speech motor control is the identification of control variables, the variables controlled by the nervous system during motor tasks. The current study examined two hypotheses regarding control variables in speech production: (1) pressure and resistance in the vocal tract are controlled, and (2) perceptual and acoustic accuracy are controlled. Aerodynamic and acoustic data were collected on 20 subjects in three conditions, normally (NT), with an open air pressure bleed tube in place (TWB), and with a closed bleed tube in place (TNB). The voice recordings collected from the speakers in the production study were used in the perceptual study. Results showed that oral pressure (Po) was significantly lower in the TWB condition than in the NT and TNB conditions. The Po in the TWB condition seemed to be related to maintenance of subglottal pressure (Ps). Examination of the perceptual and acoustic data indicated that perceptual accuracy for [a] was achieved by maintaining Ps to preserve a steady sound pressure level, fundamental frequency, and voicing. Overall, it appeared speakers controlled pressure in compensating, but for the ultimate goal of maintaining acoustic and perceptual accuracy.

Development of materials for the clinical assessment of speech recognition: the speech sound pattern discrimination test.

The purpose of this investigation was to evaluate the validity and reliability of materials designed for an assessment procedure capable of making meaningful distinctions in speech recognition ability among individuals having mild-to-moderate hearing losses. Sets of phonetic contrasts were presented within sentence contexts to 53 listeners (22 normal hearing, 31 hearing impaired) in 4 listening conditions (quiet and with background competition at signal-to-noise ratios of +5, 0, and -5 dB). The listeners were asked to discriminate pairs of sentences (e.g., "The man hid the dog" and "The man hit the dog") using same-different judgments. Their performances were analyzed in a manner enabling comparisons among items in terms of the classification of phonetic contrasts. Listener performance was also compared to performance on a set of independent variables, including the W-22 and QuickSIN speech tests, high-frequency hearing loss, speech reception threshold, listener age, and others. Results indicated that the new materials distinguished the normal-hearing from the hearing-impaired group and that listener performance (a) declined about 17% for each 5 dB decrement in SNR and (b) was influenced by the phonetic content of items in a manner similar to that reported by G. A. Miller and P. E. Nicely (1955). The performances of the hearing-impaired listeners were much more strongly related to high-frequency hearing loss, listener age, and other variables than were their performances on either the W-22 or QuickSIN tests. These findings are discussed with specific reference to the use of a mathematical model (i.e., the Rasch model for person measurement) for scaling items along a continuum of difficulty. The mathematical model and associated item difficulty values will serve as the basis for construction of a clinically useful computerized, adaptive test of speech recognition ability known as the Speech Sound Pattern Discrimination Test (Bochner, J., Garrison, W., Palmer, L., MacKenzie, D., & Braveman, A., 1997).