Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
1.
Front Vet Sci ; 11: 1364815, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38435369

RESUMO

Exogenous supplementation of guanidinoacetic acid can mechanistically regulate the energy distribution in muscle cells. This study aimed to investigate the effects of guanidinoacetic acid supplementation on liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks. We randomly divided 480 42 days-old female Jiaji ducks into four groups with six replicates and 20 ducks for each replicate. The control group was fed the basal diet, and the experimental groups were fed the basal diet with 400, 600, and 800 mg/kg (GA400, GA600, and GA800) guanidinoacetic acid, respectively. Compared with the control group, (1) the total cholesterol (p = 0.0262), triglycerides (p = 0.0357), malondialdehyde (p = 0.0452) contents were lower in GA400, GA600 and GA800 in the liver; (2) the total cholesterol (p = 0.0365), triglycerides (p = 0.0459), and malondialdehyde (p = 0.0326) contents in breast muscle were decreased in GA400, GA600 and GA800; (3) the high density lipoprotein (p = 0.0356) and apolipoprotein-A1 (p = 0.0125) contents were increased in GA600 in the liver; (4) the apolipoprotein-A1 contents (p = 0.0489) in breast muscle were higher in GA600 and GA800; (5) the lipoprotein lipase contents (p = 0.0325) in the liver were higher in GA600 and GA800; (6) the malate dehydrogenase contents (p = 0.0269) in breast muscle were lower in GA400, GA600, and GA800; (7) the insulin induced gene 1 (p = 0.0326), fatty acid transport protein 1 (p = 0.0412), and lipoprotein lipase (p = 0.0235) relative expression were higher in GA400, GA600, and GA800 in the liver; (8) the insulin induced gene 1 (p = 0.0269), fatty acid transport protein 1 (p = 0.0234), and lipoprotein lipase (p = 0.0425) relative expression were increased in GA400, GA600, and GA800 in breast muscle. In this study, the optimum dosage of 600 mg/kg guanidinoacetic acid improved the liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks.

2.
Neurol Ther ; 13(2): 475-495, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38367176

RESUMO

INTRODUCTION: No evidence has established a direct causal relationship between early microcirculation disturbance after aneurysmal subarachnoid hemorrhage (aSAH) and neurological function prognosis, which is the key pathophysiological mechanism of early brain injury (EBI) in patients with aSAH. METHODS: A total of 252 patients with aSAH were enrolled in the Neurosurgical Intensive Care Unit of Southwest Hospital between January 2020 and December 2022 and divided into the no neurological deterioration, early neurological deterioration, and delayed neurological deterioration groups. Indicators of microcirculation disorders in EBI included regional cerebral oxygen saturation (rSO2) measured by near-infrared spectroscopy (NIRS), brain oxygen monitoring, and other clinical parameters for evaluating neurological function and determining the prognosis of patients with aSAH. RESULTS: Our data suggest that the rSO2 is generally lower in patients who develop neurological deterioration than in those who do not and that there is at least one time point in the population of patients who develop neurological deterioration where left and right cerebral hemisphere differences can be significantly monitored by NIRS. An unordered multiple-classification logistic regression model was constructed, and the results revealed that multiple factors were effective predictors of early neurological deterioration: reoperation, history of brain surgery, World Federation of Neurosurgical Societies (WFNS) grade 4-5, Fisher grade 3-4, SAFIRE grade 3-5, abnormal serum sodium and potassium levels, and reduced rSO2 during the perioperative period. However, for delayed neurological deterioration in patients with aSAH, only a history of brain surgery and perioperative RBC count were predictive indicators. CONCLUSIONS: The rSO2 concentration in patients with neurological deterioration is generally lower than that in patients without neurological deterioration, and at least one time point in the population with neurological deterioration can be significantly monitored via NIRS. However, further studies are needed to determine the role of microcirculation and other predictive factors in the neurocritical management of EBI after aSAH, as these factors can reduce the incidence of adverse outcomes and mortality during hospitalization.

3.
Animals (Basel) ; 14(2)2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38254372

RESUMO

The experiment aimed to investigate the effects of dietary lycopene on the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens. We randomly divided five hundred and seventy-six one-day-old male broilers into four groups each with six replicates and 24 chickens in each replicate. The control group (CG) was fed the basal diet, and the other groups were given powder lycopene of 10, 20, and 30 mg/kg lycopene (LP10, LP20, and LP30, respectively). Compared with the control group, (1) the dietary lycopene increased (p = 0.001) the average daily gain and decreased (p = 0.033) the feed conversion ratio in the experimental groups; (2) the glutathione peroxidase enzyme contents in LP20 were higher (p =< 0.001) in myocardium; (3) the crude protein contents were higher (p = 0.007) in the group treated with 30 mg/kg dietary lycopene; (4) the jejunum villous height was higher (p = 0.040) in LP20; (5) the Unclassified-f-Ruminococcaceae relative abundance was significantly higher (p = 0.043) in LP20. In this study, adding 20 mg/kg dietary lycopene to the broiler chickens' diets improved the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens.

4.
Int J Surg Pathol ; : 10668969231195072, 2023 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-37715637

RESUMO

Fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) is a rare and aggressive tumor characterized by pathogenic alterations in the fumarate hydratase (FH) gene. Clear cell renal cell carcinoma (clear cell RCC) is a common renal cell carcinoma (RCC) associated with von Hippel-Lindau (VHL) gene variations. Here, we reported a case of bilateral RCCs. A 60-year-old man was admitted to hospital with a 3.6 cm × 3.3 cm mass in the right kidney and a 2.8 cm × 2.3 cm nodule in the left kidney. Pathologically, the right tumor showed a nested growth pattern of cells with clear cytoplasm and was FH positive and 2-succinylcysteine (2SC) negative. The left tumor demonstrated a high-grade papillary pattern and was FH negative and 2SC positive. Whole-exome sequencing and Sanger sequencing identified a germline FH c.563A > T mutation in both the tumors and an additional somatic VHL c.479_480insA mutation in the right tumor, confirming the diagnosis of clear cell RCC and FH-deficient RCC in the right and left kidneys, respectively. We reported a rare case of synchronous bilateral clear cell RCC (right) and FH-deficient RCC (left) likely driven by somatic VHL mutation and germline FH mutation, respectively.

5.
Brain Behav ; 13(7): e3041, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37137534

RESUMO

OBJECTIVE: As a complex and acute brain dysfunction, if postoperative delirium (POD) occurs in the postoperative period, it will lead to a prolonged length of stay in the critical care unit, with increased hospitalization costs and higher mortality. A few case reports inspired us to pay close attention to pituitary tumor-associated delirium. We hypothesized that the changes in hormone levels after pituitary tumor resection might be associated with POD occurrence. METHODS: Retrospective analysis was performed on data from a single-center cohort study conducted at Southwest Hospital between January 2018 and May 2022. A total of 360 patients with pituitary tumors who underwent endoscope-assisted transsphenoidal pituitary tumor resection were divided into two groups at a 1:3 ratio, with 36 patients in the POD group and 108 patients in the non-POD group matched by propensity score, age, sex, and tumor size. Basic characteristics, pituitary adenoma features, endocrine levels and other biochemical indicators, and Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) for postoperative delirium were documented for further analysis. RESULTS: Lower insulin-like growth factor-1 (IGF-1, p = .024) and corticotropin-releasing hormone (CRH, p = .005) levels were closely associated with postoperative delirium and with high levels of blood glucose (GLU, p = .023) after surgery. Subsequent analysis indicated that serum potassium (OR: 0.311, 95% CI 0.103-0.935), sodium (OR: 0.991, 95% CI 0.983-1.000), CRH (OR: 0.964, 95% CI 0.936-0.994), and GLU (OR: 1.654, 95% CI 1.137-2.406) levels in the perioperative period were independent risk factors for delirium. CONCLUSIONS: Our study indicated that lower serum CRH, potassium, sodium, and GLU levels may be associated with the occurrence of POD after endoscopic-assisted transsphenoidal surgery. These data provide preliminary evidence for the management of POD in pituitary adenoma patients after surgery. Further studies are needed to identify pharmacological and nonpharmacological multicomponent treatment strategies.


Assuntos
Adenoma , Delírio do Despertar , Neoplasias Hipofisárias , Humanos , Neoplasias Hipofisárias/cirurgia , Neoplasias Hipofisárias/complicações , Neoplasias Hipofisárias/patologia , Estudos de Coortes , Estudos Retrospectivos , Delírio do Despertar/complicações , Endoscópios/efeitos adversos , Sódio , Adenoma/cirurgia , Adenoma/complicações , Adenoma/patologia , Hormônios , Fatores de Risco , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/epidemiologia , Resultado do Tratamento
6.
J Am Acad Audiol ; 33(2): 75-81, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-36049753

RESUMO

BACKGROUND: Tinnitus is a prevalent auditory disorder that can become severely debilitating. Despite decades of investigation, there remains no conclusive cure for tinnitus. Clinical practice guidelines (CPGs) are available for assessing and managing tinnitus. Even though such guidelines have been available for several years, the degree that audiologists adhere to them has remained unexplored. PURPOSE OF STUDY: To determine what clinical practices are commonly used by audiologists in the assessment and management of the patient population with tinnitus, we administered an online survey to audiologists practicing in the United States and Canada. RESULTS: Among the audiologists that completed the survey and were included in the final analysis (n = 61), 70% were from the United States and 30% were from Canada. The audiologists represented a wide range of clinical experience (1-35 years). On average, those who completed the survey were relatively confident in their ability to assess and manage tinnitus patients indicated by a 0 to 100 Likert scale, with 0 representing no confidence (mean 72.5, ± 21.5 standard deviation). The most commonly reported tinnitus assessment tools were pure tone audiogram (0.25-8 kHz), administration of standardized questionnaires, and tinnitus pitch and loudness matching. Approximately half (55%) of audiologists indicated they include otoacoustic emissions, while less audiologists (<40%) reported measuring high-frequency thresholds, minimum masking levels, or loudness discomfort levels. The most common recommendation for tinnitus patients was amplification (87%), followed by counseling (80%) and sound therapy (79%). CONCLUSION: Few audiologists administer a truly comprehensive tinnitus assessment and ∼20% indicated not recommending counseling or sound therapy to manage tinnitus. The results are discussed in the context of what is explicitly indicated in published CPGs, professional organization recommendations, and recent findings of peer-reviewed literature.


Assuntos
Audiologistas , Zumbido , Audiometria , Testes Auditivos , Humanos , Inquéritos e Questionários , Zumbido/diagnóstico , Zumbido/terapia , Estados Unidos
7.
Int J Audiol ; 61(8): 642-654, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-34369262

RESUMO

OBJECTIVE: Conventional directional hearing aid microphone technology may obstruct listening intentions when the talker and listener walk side by side. The purpose of the current study was to evaluate hearing aids that use a motion sensor to address listening needs during walking. DESIGN: Each participant completed two walks in randomised order, one walk with each of two hearing aid programs: (1) conventional beamformer adaptation that activated an adaptive, multiband beamformer in loud environments and (2) motion-based beamformer adaptation that activated a pinna-mimicking microphone setting when walking was detected. Participants walked along a pre-defined track and completed tasks assessing speech understanding and environmental awareness. STUDY SAMPLE: Participants were 22 older adults with moderate-to-severe hearing loss and experience using hearing aids. RESULTS: More participants preferred the motion-based than conventional beamformer adaptation for speech understanding, environmental awareness, overall listening, and sound quality (p < 0.05). Measures of speech understanding (p < 0.01) and localisation of sound stimuli (p < 0.05) were significantly better with motion-based than conventional beamformer adaptation. CONCLUSIONS: The results suggest that hearing aid users can benefit from beamforming that uses motion sensor input to adapt the signal processing according to the user's activity. The real-world setup of this study had limitations.


Assuntos
Auxiliares de Audição , Perda Auditiva Neurossensorial , Percepção da Fala , Idoso , Desenho de Equipamento , Perda Auditiva Neurossensorial/reabilitação , Humanos
8.
Trends Hear ; 25: 2331216521997610, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33710928

RESUMO

The aim of this study was to evaluate the efficacy of dual compression for Mandarin-speaking hearing aid users. Dual compression combines fast and slow compressors operating simultaneously across all frequency channels. The study participants were 31 hearing aid users with symmetrical moderate-to-severe hearing loss, with a mean age of 67 years. A new pair of 20-channel behind-the-ear hearing aids (i.e., Phonak Bolero B90-P) was used during the testing. The results revealed a significant improvement in speech reception thresholds in noise when switching from fast-acting compression to dual compression. The sound quality ratings revealed that most listeners preferred dual compression to fast-acting compression for listening effort, listening comfort, speech clarity, and overall sound quality at +4 dB signal-to-noise ratio. These results are consistent with predictions based on the theoretical understanding of dual and fast-acting compression. However, whether these results can be generalized to other languages or other dual compression systems should be verified by future studies.


Assuntos
Auxiliares de Audição , Perda Auditiva Neurossensorial , Percepção da Fala , Adulto , Idoso , Feminino , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Inteligibilidade da Fala
9.
Int J Audiol ; 59(7): 524-533, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32441563

RESUMO

Objective: The purpose of the present study was to examine the effects of NLFC fitting in hearing aids and auditory acclimatisation on speech perception and sound-quality rating in hearing-impaired, native Mandarin-speaking adult listeners.Design: Mandarin consonant, vowel and tone recognition were tested in quiet and sentence recognition in noise (speech-shaped noise at a +5 dB signal-to-noise ratio) with NLFC-on and NLFC-off. Sound-quality ratings were collected on a 0-10 scale at each test session. A generalised linear model and correlational analyses were performed.Study sample: Thirty native Mandarin-speaking adults with moderate-to-severe sensorineural hearing loss were recruited.Results: The hearing-impaired listeners showed significantly higher accuracy with NLFC-on than with NLFC-off for consonant and sentence recognition and the recognition performance improved with both NLFC-on and off as a function of increased length of use. The satisfaction score of sound-quality ratings for different types of sounds significantly increased with NLFC-on than with NLFC-off. The speech recognition results showed moderate to strong correlation with the unaided hearing thresholds.Conclusion: For native Mandarin-speaking listeners with hearing loss, the NLFC technology provided modest but significant improvement in Mandarin fricative and sentence recognition. Subjectively, the naturalness and overall preference of sound-quality satisfaction judgement also improved with NLFC.


Assuntos
Limiar Auditivo , Correção de Deficiência Auditiva/instrumentação , Auxiliares de Audição/psicologia , Perda Auditiva Neurossensorial/reabilitação , Percepção da Fala , Adulto , Idoso , Idoso de 80 Anos ou mais , China , Correção de Deficiência Auditiva/psicologia , Correlação de Dados , Feminino , Humanos , Idioma , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Ruído , Teste do Limiar de Recepção da Fala
10.
J Am Acad Audiol ; 31(8): 590-598, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32340058

RESUMO

BACKGROUND: Mandarin Chinese has a rich repertoire of high-frequency speech sounds. This may pose a remarkable challenge to hearing-impaired listeners who speak Mandarin Chinese because of their high-frequency sloping hearing loss. An adaptive nonlinear frequency compression (adaptive NLFC) algorithm has been implemented in contemporary hearing aids to alleviate the problem. PURPOSE: The present study examined the performance of speech perception and sound-quality rating in Mandarin-speaking hearing-impaired listeners using hearing aids fitted with adaptive NLFC (i.e., SoundRecover2 or SR2) at different parameter settings. RESEARCH DESIGN: Hearing-impaired listeners' phoneme detection thresholds, speech reception thresholds, and sound-quality ratings were collected with various SR2 settings. STUDY SAMPLE: The participants included 15 Mandarin-speaking adults aged 32 to 84 years old who had symmetric sloping severe-to-profound sensorineural hearing loss. INTERVENTION: The participants were fitted bilaterally with Phonak Naida V90-SP hearing aids. DATA COLLECTION AND ANALYSIS: The outcome measures included phoneme detection threshold using the Mandarin Phonak Phoneme Perception test, speech reception threshold using the Mandarin hearing in noise test (M-HINT), and sound-quality ratings on human speech in quiet and noise, bird chirps, and music in quiet. For each test, five experimental settings were applied and compared: SR2-off, SR2-weak, SR2-default, SR2-strong 1, and SR2-strong 2. RESULTS: The results showed that listeners performed significantly better with SR2-strong 1 and SR2-strong 2 settings than with SR2-off or SR2-weak settings for speech reception threshold and phoneme detection threshold. However, no significant improvement was observed in sound-quality ratings among different settings. CONCLUSIONS: These preliminary findings suggested that the adaptive NLFC algorithm provides perceptual benefit to Mandarin-speaking people with severe-to-profound hearing loss.


Assuntos
Auxiliares de Audição , Perda Auditiva Neurossensorial , Percepção da Fala , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Perda Auditiva de Alta Frequência , Humanos , Pessoa de Meia-Idade , Fonética
11.
Ear Hear ; 41(3): 532-538, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31369470

RESUMO

OBJECTIVES: Lexical tone information provides redundant cues for the recognition of Mandarin sentences in listeners with normal hearing in quiet conditions. The contribution of lexical tones to Mandarin sentence recognition in listeners with hearing aids (HAs) is unclear. This study aimed to remove lexical tone information and examine the effects on Mandarin sentence intelligibility in HA users. The second objective was to investigate the contribution of cognitive abilities (i.e., general cognitive ability, working memory, and attention) on Mandarin sentence perception when the presentation of lexical tone information was mismatched. DESIGN: A text-to-speech synthesis engine was used to manipulate Mandarin sentences into three test conditions: (1) a Normal Tone test condition, where no alterations were made to lexical tones within sentences; (2) a Flat Tone test condition, where lexical tones were all changed into tone 1 (i.e., the flat tone); and (3) a Random Tone test condition, where each word in test sentences was randomly assigned one of four Mandarin lexical tones. The manipulated sentence signals were presented to 32 listeners with HAs in both quiet and noisy environments at an 8 dB signal to noise ratio. RESULTS: Speech intelligibility was reduced significantly (by approximately 40 percentage points) in the presence of mismatched lexical tone information in both quiet and noise. The difficulty in correctly identifying sentences with mismatched lexical tones among adults with hearing loss was significantly greater than that of adults with normal hearing. Cognitive function was not significantly related to a decline in speech recognition scores. CONCLUSIONS: Contextual and other phonemic cues (i.e., consonants and vowels) are inadequate for HA users to perceive sentences with mismatched lexical tone contours in quiet or noise. Also, HA users with better cognitive function could not compensate for the loss of lexical tone information. These results highlight the importance of accurately representing lexical tone information for Mandarin speakers using HAs.


Assuntos
Auxiliares de Audição , Percepção da Fala , Adulto , Povo Asiático , Humanos , Ruído , Fonética , Inteligibilidade da Fala
12.
J Acoust Soc Am ; 143(3): 1578, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29604675

RESUMO

The present study examined the change in spectral properties of Mandarin vowels and fricatives caused by nonlinear frequency compression (NLFC) used in hearing instruments and how these changes affect the perception of speech sounds in normal-hearing listeners. Speech materials, including a list of Mandarin monosyllables in the form of /dV/ (12 vowels) and /Ca/ (five fricatives), were recorded from 20 normal-hearing, native Mandarin-speaking adults (ten males and ten females). NLFC was based on Phonak SoundRecover algorithms. The speech materials were processed with six different NLFC parameter settings. Detailed acoustic analysis revealed that the high front vowel /i/ and certain compound vowels containing /i/ demonstrated positional deviation in certain processed conditions in comparison to the unprocessed condition. All five fricatives showed acoustic changes in spectral features in all processed conditions. Fourteen Mandarin-speaking, normal-hearing adult listeners performed phoneme recognition with the six NLFC processing conditions. When the cut-off frequency was set relatively low, recognition of /s/ was detrimentally affected, whereas none of the NLFC processing configurations affected the other phonemes. The discrepancy between the considerable acoustic changes and the negligible adverse effects on perceptual outcomes is partially accounted for by the phonology system and phonotactic constraints in Mandarin.


Assuntos
Fonética , Acústica da Fala , Percepção da Fala , Adulto , China , Feminino , Voluntários Saudáveis , Humanos , Idioma , Masculino , Espectrografia do Som
13.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 31(7): 862-869, 2017 07 15.
Artigo em Chinês | MEDLINE | ID: mdl-29798533

RESUMO

Objective: To observe the effect of stromal vascular fraction cells (SVFs) from rat fat tissue combined with sustained release of recombinant human bone morphogenetic protein-2 (rhBMP-2) in promoting the lumbar fusion in rat model. Methods: SVFs were harvested from subcutaneous fat of bilateral inguinal region of 4-month-old rat through the collagenase I digestion. The sustained release carrier was prepared via covalent bond of the rhBMP-2 and ß-tricalcium phosphate (ß-TCP) by the biominetic apatite coating process. The sustained release effect was measured by BCA method. Thirty-two rats were selected to establish the posterolateral lumbar fusion model and were divided into 4 groups, 8 rats each group. The decalcified bone matrix (DBX) scaffold+PBS, DBX scaffold+rhBMP-2/ß-TCP sustained release carrier, DBX scaffold+SVFs, and DBX scaffold+rhBMP-2/ß-TCP sustained release carrier+SVFs were implanted in groups A, B, C, and D respectively. X-ray films, manual spine palpation, and high-resolution micro-CT were used to evaluate spinal fusion at 8 weeks after operation; bone mineral density (BMD) and bone volume fraction were analyzed; the new bone formation was evaluated by HE staining and Masson's trichrome staining, osteocalcin (OCN) was detected by immunohistochemical staining. Results: The cumulative release amount of rhBMP-2 was about 40% at 2 weeks, indicating sustained release effect of rhBMP-2; while the control group was almost released within 2 weeks. At 8 weeks, the combination of manual spine palpation, X-ray, and micro-CT evaluation showed that group D had the strongest bone formation (100%, 8/8), followed by group B (75%, 6/8), group C (37.5%, 3/8), and group A (12.5%, 1/8). Micro-CT analysis showed BMD and bone volume fraction were significantly higher in group D than groups A, B, and C ( P<0.05), and in group B than groups A and C ( P<0.05). HE staining, Masson's trichrome staining, and immunohistochemistry staining for OCN staining exhibited a large number of cartilage cells with bone matrix deposition, and an active osteogenic process similar to the mineralization of long bones in group D. The bone formation of group B was weaker than that of group D, and there was no effective new bone formation in groups A and C. Conclusion: The combination of sustained release of rhBMP-2 and freshly SVFs can significantly promote spinal fusion in rat model, providing a theoretical basis for further clinical applications.


Assuntos
Proteína Morfogenética Óssea 2/metabolismo , Osteogênese , Fusão Vertebral , Fator de Crescimento Transformador beta/metabolismo , Tecido Adiposo/metabolismo , Animais , Preparações de Ação Retardada , Humanos , Ratos , Proteínas Recombinantes/metabolismo
14.
J Acoust Soc Am ; 127(4): 2461-5, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20370029

RESUMO

Decision weights were estimated in a profile analysis task to determine whether onset asynchronies between the signal component and the nonsignal components encourage the segregation of the signal relative to the other components. The signal component onset was either synchronous or asynchronous with respect to the nonsignal components. In the asynchronous conditions, thresholds were higher and the decision weights were less efficient than in the synchronous conditions. These data are largely consistent with a segregation hypothesis: onset asynchrony encourages subjects to shift strategies from one of spectral shape discrimination toward one of intensity discrimination.


Assuntos
Percepção Auditiva , Mascaramento Perceptivo , Detecção de Sinal Psicológico , Estimulação Acústica , Adulto , Limiar Auditivo , Humanos , Modelos Lineares , Modelos Logísticos , Discriminação da Altura Tonal , Psicoacústica , Análise e Desempenho de Tarefas , Fatores de Tempo , Adulto Jovem
15.
J Acoust Soc Am ; 123(5): 2692-700, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18529188

RESUMO

Narrowband noise stimuli were used to derive relative weights for detecting frequency glides in a yes/no procedure. One stimulus set was restricted to the duration of the glide. For the second stimulus set, there were fringe noise bands preceding and following the glide. For both sets, the center frequency of the linear glide was either fixed at 1000 Hz or randomly chosen on each trial from the range of 800-1200 Hz. Relative weights as a function of time were derived using a linear model and the linear classification method [A. Ahumada, J. Vis., 2, 121-131 (2002)]. Sensitivity was better for the fixed- than random-frequency conditions, and weight patterns from the random-frequency conditions were less reliable than those obtained from the fixed-frequency conditions. The magnitudes of the relative weights tended to be larger for the second half of the stimulus, suggesting that subjects paid more attention to the later than the earlier parts of stimuli. In the random-frequency conditions, the linear model failed to account for subjects' performance unless the stimuli were expressed in terms of relative changes in frequency rather than absolute frequency.


Assuntos
Atenção , Limiar Auditivo , Ruído , Ondas de Rádio , Humanos , Matemática , Modelos Biológicos , Mascaramento Perceptivo , Psicoacústica , Sensibilidade e Especificidade , Localização de Som
16.
J Acoust Soc Am ; 123(1): 302-14, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18177160

RESUMO

Sound localization cues generally include interaural time difference, interaural intensity difference, and spectral cues. The purpose of this study is to investigate the important spectral cues involved in so-called head related transfer functions (HRTFs) using a combination of HRTF analyses and a virtual sound localization (VSL) experiment. Previous psychoacoustical and physiological studies have both suggested the existence of spectral modulation frequency (SMF) channels for analyzing spectral information (e.g., the spectral cues coded in HRTFs). SMFs are in a domain related to the Fourier transform of HRTFs. The relationship between various SMF regions and sound localization was tested here by filtering or enhancing HRTFs in the SMF domain under a series of conditions using a VSL experiment. Present results revealed that azimuth localization was not significantly affected by HRTF manipulation. Applying notch filters between 0.1 and 0.4 cyclesoctave or between 0.35 and 0.65 cyclesoctave resulted in significantly less accurate elevation responses at low elevations, while spectral enhancement in these two SMF regions did not produce a significant change in sound localization. Likewise, low-pass filtering at 2 cyclesoctave did not significantly influence localization accuracy, suggesting that the major cues for sound localization are in the SMF region below 2 cyclesoctave.


Assuntos
Percepção Auditiva/fisiologia , Localização de Som , Sinais (Psicologia) , Humanos , Interface Usuário-Computador
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...