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At least 1,693 records · Page 94Linked to original sources
PubMed2002

Temporal integration: intentional sound discrimination does not modulate stimulus-driven processes in auditory event synthesis.

OBJECTIVE: Our previous study showed that the auditory context could influence whether two successive acoustic changes occurring within the temporal integration window (approximately 200ms) were pre-attentively encoded as a single auditory event or as two discrete events (Cogn Brain Res 12 (2001) 431). The aim of the current study was to assess whether top-down processes could influence the stimulus-driven processes in determining what constitutes an auditory event. METHODS: Electroencepholagram (EEG) was recorded from 11 scalp electrodes to frequently occurring standard and infrequently occurring deviant sounds. Within the stimulus blocks, deviants either occurred only in pairs (successive feature changes) or both singly and in pairs. Event-related potential indices of change and target detection, the mismatch negativity (MMN) and the N2b component, respectively, were compared with the simultaneously measured performance in discriminating the deviants. RESULTS: Even though subjects could voluntarily distinguish the two successive auditory feature changes from each other, which was also indicated by the elicitation of the N2b target-detection response, top-down processes did not modify the event organization reflected by the MMN response. CONCLUSIONS: Top-down processes can extract elemental auditory information from a single integrated acoustic event, but the extraction occurs at a later processing stage than the one whose outcome is indexed by MMN. SIGNIFICANCE: Initial processes of auditory event-formation are fully governed by the context within which the sounds occur. Perception of the deviants as two separate sound events (the top-down effects) did not change the initial neural representation of the same deviants as one event (indexed by the MMN), without a corresponding change in the stimulus-driven sound organization.

Acoustic Stimulation↗
PubMed2006

Analysis of failure of voice production by a sound-producing voice prosthesis.

OBJECTIVE: To analyse the cause of failing voice production by a sound-producing voice prosthesis (SPVP). METHODS: The functioning of a prototype SPVP is described in a female laryngectomee before and after its sound-producing mechanism was impeded by tracheal phlegm. This assessment included: perceptual voice evaluation of read-aloud prose by an expert listener; inspection of the malfunctioning SPVP; and aero-acoustical in vivo registrations using a computer-based data acquisition system. RESULTS: Sound-producing voice prosthesis speech is higher pitched, stronger, contains less aperiodic noise and requires a lower airflow rate than the patient's regular tracheoesophageal (TE) shunt speech. Tracheal phlegm caused malfunction of the vibrating silicone lip of the SPVP by causing it to stick to its stainless steel container in an opened position, thereby reducing the SPVP to no more than a regular TE shunt valve from a functional point of view. Tracheal phonatory pressure and dynamic vocal intensity range were not affected by the functional status of the SPVP. CONCLUSIONS: To exploit the advantages an SPVP could offer female laryngectomees with an atonic or severely hypotonic pharyngoesophageal segment, the sound-producing mechanism of the SPVP needs to be less vulnerable to tracheal phlegm.

Aged, 80 and over↗
PubMed2003

Relaxing intraoperative natural sound blunts haemodynamic change at the emergence from propofol general anaesthesia and increases the acceptability of anaesthesia to the patient.

BACKGROUND: It is known that auditory input, such as comforting music or sound, blunts the human response to surgical stress in conscious patients under regional anaesthesia. As auditory perception has been demonstrated to remain active under general anaesthesia, playing comforting sounds to patients under general anaesthesia might also modulate the response of these patients to surgical stress. METHODS: Fifty-nine patients scheduled for laparoscopic cholecystectomy were anaesthetized with propofol general anaesthesia in combination with epidural anaesthesia. Natural sounds, chosen preoperatively by each patient as being comforting, were played to 29 patients using headphones during surgery (S group) and the remainder of the patients (n = 30) were fitted with dummy open-type headphones (N group). We compared the haemodynamic change during anaesthesia and the acceptability of anaesthetic practice between the two groups in a randomized double-blind design. RESULTS: There were no differences in haemodynamics between the S and N groups during surgery. During the emergence from anaesthesia, the mean blood pressure and heart rate gradually increased; both parameters were significantly higher in the N group than in the S group. Postoperatively, patients in the S group perceived the experience of anaesthesia as significantly more acceptable than did those in the N group. CONCLUSION: These findings indicate that allowing patients comforting background sounds during general anaesthesia may blunt haemodynamic changes upon emergence from general anaesthesia and increase the acceptability of the experience of anaesthesia.

Aged↗
PubMed2003

In vitro study of caries detection through sound dentin using a laser fluorescence device, DIAGNOdent.

The objective of this study was to investigate the feasibility of proximal surface caries detection using a laser fluorescence device, DIAGNOdent, through the sound dentin surrounding the cavity wall after removal of occlusal caries. Extracted sound human molars were ground to prepare horizontal and vertical dentin plates 1.4 mm thick. Extracted carious human molars were reduced in thickness horizontally from the occlusal surfaces until exposure of the dentin caries. The dentin plate was placed on the carious tooth. Before and after gradual thinning of the dentin plate from approximately 1.4 mm to 0.2 mm thick, the dentin caries was measured 10 times through the plate by the laser fluorescence device with a cone-shaped tip or a broad tip. When the dentin plate was reduced to less than 0.3 mm thick (using a combination of a horizontal plate and cone-shaped tip) or 0.2 mm thick (using the other combinations), the values measured with the laser fluorescence device were significantly larger than the values before reducing the thickness of the dentin. Based on these results, the device offers potential use as one of the screening tests for proximal surface caries detection through sound dentin when the sound dentin between tip and caries is thin.

Analysis of Variance↗
PubMed1993

Common factors in the identification of an assortment of brief everyday sounds.

Acoustic, ecological, perceptual and cognitive factors that are common in the identification of 41 brief, varied sounds were evaluated. In Experiment 1, identification time and accuracy, causal uncertainty values, and spectral and temporal properties of the sounds were obtained. Experiment 2 was a survey to obtain ecological frequency counts. Experiment 3 solicited perceptual-cognitive ratings. Factor analyses of spectral parameters and perceptual-cognitive ratings were performed. Identification time and causal uncertainty are highly interrelated, and both are related to ecological frequency and the presence of harmonics and similar spectral bursts. Experiments 4 and 5 used a priming paradigm to verify correlational relationships between identification time and causal uncertainty and to assess the effect of sound typicality. Results support a hybrid approach for theories of everyday sound identification.

Adult↗
PubMed1998

Right parietal cortex is involved in the perception of sound movement in humans.

Changes in the delay (phase) and amplitude of sound at the ears are cues for the analysis of sound movement. The detection of these cues depends on the convergence of the inputs to each ear, a process that first occurs in the brainstem. The conscious perception of these cues is likely to involve higher centers. Using novel stimuli that produce different perceptions of movement in the presence of identical phase and amplitude modulation components, we have demonstrated human brain areas that are active specifically during the perception of sound movement. Both functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) demonstrated the involvement of the right parietal cortex in sound movement perception with these stimuli.

Acoustic Stimulation↗
PubMedDate not supplied

Vocal tract resonances in oscine bird sound production: evidence from birdsongs in a helium atmosphere.

The complexity and dependence on learning of many bird sounds have suggested parallels between birdsong and human speech, but the mechanisms by which each is produced have been supposed to differ markedly. In human speech, resonances of the vocal tract are thought to modulate in complex ways the sound produced by vibration of the vocal folds. The current theory of birdsong production holds that all variation in sound quality arises from the primary sound-producing organ, the syrinx, and that resonances of the vocal tract play no part. Here I present evidence, obtained from acoustic analyses of birdsongs recorded in a helium atmosphere, which contradicts this hypothesis. Not only does the songbird's vocal tract act as an acoustic filter, but its filter characteristics are actively coordinated with the output of the syrinx. Songbird and human phonation are thus more analogous than previously thought, in that both require coordination of an array of diverse motor systems.

Animals↗
PubMed2003

Processing of low-probability sounds by cortical neurons.

The ability to detect rare auditory events can be critical for survival. We report here that neurons in cat primary auditory cortex (A1) responded more strongly to a rarely presented sound than to the same sound when it was common. For the rare stimuli, we used both frequency and amplitude deviants. Moreover, some A1 neurons showed hyperacuity for frequency deviants--a frequency resolution one order of magnitude better than receptive field widths in A1. In contrast, auditory thalamic neurons were insensitive to the probability of frequency deviants. These phenomena resulted from stimulus-specific adaptation in A1, which may be a single-neuron correlate of an extensively studied cortical potential--mismatch negativity--that is evoked by rare sounds. Our results thus indicate that A1 neurons, in addition to processing the acoustic features of sounds, may also be involved in sensory memory and novelty detection.

Acoustic Stimulation↗
PubMed2001

Sound attenuation of polymerizing actin reflects supramolecular structures: viscoelastic properties of actin gels modified by cytochalasin D, profilin and alpha-actinin.

Polymerization and depolymerization of cytoskeletal elements maintaining cytoplasmic stiffness are key factors in the control of cell crawling. Rheometry is a significant tool in determining the mechanical properties of the single elements in vitro. Viscoelasticity of gels formed by these polymers strongly depends on both the length and the associations of the filaments (e.g. entanglements, annealings and side-by-side associations). Ultrasound attenuation is related to viscosity, sound velocity and supramolecular structures in the sample. In combination with a small glass fibre (2 mm x 50 microm), serving as a viscosity sensor, an acoustic microscope was used to measure the elasticity and acoustic attenuation of actin solutions. Changes in acoustic attenuation of polymerizing actin by far exceed the values expected from calculations based on changes in viscosity and sound velocity. During the lag-phase of actin polymerization, attenuation slightly decreases, depending on actin concentration. After the half-maximum viscosity is accomplished and elasticity turns into steady state, attenuation distinctly rises. Changes in ultrasound attenuation depend on actin concentration, and they are modulated by the addition of alpha-actinin, cytochalasin D and profilin. Thus absorption and scattering of sound on the polymerization of actin is related to the packing density of the actin net, entanglements and the length of the actin filaments. Shortening of actin filaments by cytochalasin D was also confirmed by electron micrographs and falling-ball viscosimetry. In addition to viscosity and elasticity, the attenuation of sound proved to be a valuable parameter in characterizing actin polymerization and the supramolecular associations of F-actin.

Acoustics↗
PubMed2004

Speech perception by students with cochlear implants using sound-field systems in classrooms.

Cochlear implants support deaf students' language development through the improved use of audition in the classroom. Unfortunately, the acoustics of typical classrooms greatly reduce auditory speech perception by these students. Sound-field systems can increase speech-to-noise ratios in classrooms and thus improve use of audition. These systems are used by 80% of students with cochlear implants who use an FM system in the classroom. The present study compares speech perception by 14 school-age cochlear implant recipients via 2 classroom sound-field systems, 1 wall-mounted and the other a personal, or desktop, system. Testing was conducted in 2 classroom environments, 1 noisy and reverberant (typical of many classrooms) and the other ideally quiet with reverberation of short duration. In the quiet room with low reverberation, both sound-field systems produced improved phoneme recognition, but there was no difference between the 2. In the noisy room with high reverberation, the sound-field benefits were greater, and the desktop systems provided more benefit than the wall-mounted systems.

Acoustics↗
PubMed2005

Impact of aberrant acoustic properties on the perception of sound quality in electrolarynx speech.

A large percentage of patients who have undergone laryngectomy to treat advanced laryngeal cancer rely on an electrolarynx (EL) to communicate verbally. Although serviceable, EL speech is plagued by shortcomings in both sound quality and intelligibility. This study sought to better quantify the relative contributions of previously identified acoustic abnormalities to the perception of degraded quality in EL speech. Ten normal listeners evaluated the sound quality of EL speech tokens that had been acoustically enhanced by (a) increased low-frequency energy, (b) EL-noise reduction, and (c) fundamental frequency variation to mimic normal pitch intonation in relation to nonenhanced EL speech, normal speech, and normal monotonous speech (fundamental frequency variation removed). In comparing all possible combinations of token pairs, listeners were asked to identify which one of each pair sounded most like normal natural speech, and then to rate on a visual analog scale how different the chosen token was from normal speech. The results indicate that although EL speech can be most improved by removing the EL noise and providing proper pitch information, the resulting quality is still well below that of normal natural speech or even that of monotonous natural speech. This suggests that, in addition to the widely acknowledged acoustic abnormalities examined in this investigation, there are other attributes that contribute significantly to the unnatural quality of EL speech. Such additional factors need to be clearly identified and remedied before EL speech can be made to more closely approximate the sound quality of normal natural speech.

Female↗
PubMed1980

Simultaneous assessment of pharyngeal wall and velar displacement for selected speech sounds.

Velar and pharyngeal wall displacements were studied simultaneously by using conventional lateral-view radiography and frontal-view tomography. Twenty-five normal adult male and female subjects were utilized. Major results pertaining to lateral pharyngeal wall displacements during speech include the following. 1) At more superior levels of the pharynx, greater mesial displacements occurred for nonnasal compared to nasal speech sounds and no significant differences were noted among the nonnasal speech sounds studied. 2) At an inferior level of the pharynx, mesial displacements were greater for low vowels compared to the other speech sounds studied but some lateral (outward) movements were observed during high vowel production for some subjects. 3) Greatest mesial displacements for all subjects ad speech sounds studied occurred at the level of and just below the plane of the hard palate. Low correlations between velar and lateral pharyngeal wall displacements were obtained for most subjects. The results do not support the hypothesis that the levator veli palatini muscle is solely involved in both velar and lateral pharyngeal wall movements.

Adult↗
PubMed1983

Perceptual organization of speech sounds by infants.

An operant head-turn procedure was used to test whether 6-month-old infants recognize the auditory similarity of speech sounds sharing a value on a phonetic-feature dimension. One group of infants was reinforced for head turns when a change occurred from a series of repeating background stimuli containing nasal consonants [( m, n, eta]) to repetitions from a category of syllables containing voiced stop consonants [( b, d, g]), or to a change from stops to nasals. The stimuli were naturally produced by both male and female talkers. The performance of infants in this "phonetic" group was compared to that of infants in a "nonphonetic" control group. Using the same procedures, these infants were reinforced for head turns to a group of phonetically unrelated speech sounds. Results indicated that the performance of infants in the group trained on phonetically related speech sounds was far superior to that of infants in the nonphonetic control group. These findings suggest that prelinguistic infants can perceptually organize speech sounds on the basis of auditory properties related to feature similarity.

Child Language↗
PubMed1993

Role of visual feedback treatment for defective /s/ sounds in patients with cleft palate.

The role of visual feedback in the treatment of defective /s/ sounds in patients with cleft palate is described. Six patients with cleft palate who were similar in age, velopharyngeal function, and type of misarticulation were selected for this study. Treatment was provided using either visual feedback or no visual feedback. Visual feedback for tongue placement was provided by the Rion Electropalatograph (EPG). Visual feedback for frication was provided by a multi-function speech training aid (MFSTA). Improvement in /s/ sound production was assessed objectively using a method described previously (Michi et al., 1986). The results indicated that visual feedback for tongue placement and frication was especially useful in the treatment of defective /s/ sounds in patients with cleft palate who exhibited abnormal posterior tongue posturing during the production of dental or alveolar sounds.

Articulation Disorders↗
PubMed2002

[The assessment of subjective distress related to hyperacusis with a self-rating questionnaire on hypersensitivity to sound].

BACKGROUND: So far there has been no adequate measure to assess or illustrate, in terms of different levels, subjective distress related to hypersensitivity to sound. METHOD AND PATIENTS: The here presented work describes and discusses the construction of a questionnaire to assess subjective distress related to hypersensitivity to sound (GUF). Between May and September 2000 226 patients that experienced suffering from hypersensitivity to sound as well as from chronic tinnitus, completed a first version of the questionnaire on admittance to the hospital. Of these patients 27.9 % were out-patients and 72.1 % were in-patients. In addition, the in-patients completed the questionnaire again during their last week of treatment. The 27 items of the GUF were interpreted by factor analysis to explore and determine the structure of the questionnaire; the number of items was reduced under the aspects of consistency and reliability. Finally, the revised version of the GUF underwent a first validation. RESULTS: The factor analysis shows three factors explaining 50.65 % variance (factor 1 [KRH], cognitive reactions to hyperacusis; factor 2 [ASV], actional/somatic behaviour; factor 3 [ERG], emotional reaction to external noises). First attempts to validate the questionnaire are promising; it appears that the GUF is also sensitive to therapy effects. CONCLUSIONS: The here presented questionnaire is suitable for identifying distinct levels of subjective distress related to hypersensitivity to sound. Thus, for the first time, there is an adequate measure for assessment available. Furthermore, results of part of the sample show that the GUF is also suitable for therapy evaluation.

Adaptation, Psychological↗
PubMed1982

[The ultra-sound diagnosis of Meckel-syndrome (author's transl)].

A case is reported of an antenatal completely sonographic diagnosis of a case of Meckel-Syndrome. During the second ultra-sound screening at 33 weeks gestation the suspicion of hydrocephalus was diagnosed. An extended ultra-sound diagnosis at 34 gestation showed the following: 1. internal hydrocephalus 2. encephalocele or meningomyelocele 3. bilateral polycystic kidneys 4. suspicious of aplasia of the diaphragm on the left 5. suspicious of hepatic cysts. The infant died a few hours after delivery. The autopsy report corroborated the essential features of the ultra-sound diagnosis. In summary these were interpreted as meckel-syndrome. This case shows that a complete antenatal diagnosis of meckel-syndrome by ultra-sound only is possible. The case also shows that diagnosis prior to 24 weeks gestation is desirable in order to carry out the necessary treatment.

Adult↗
PubMed2004

Human posterior auditory cortex gates novel sounds to consciousness.

Life or death in hostile environments depends crucially on one's ability to detect and gate novel sounds to awareness, such as that of a twig cracking under the paw of a stalking predator in a noisy jungle. Two distinct auditory cortex processes have been thought to underlie this phenomenon: (i) attenuation of the so-called N1 response with repeated stimulation and (ii) elicitation of a mismatch negativity response (MMN) by changes in repetitive aspects of auditory stimulation. This division has been based on previous studies suggesting that, unlike for the N1, repetitive "standard" stimuli preceding a physically different "novel" stimulus constitute a prerequisite to MMN elicitation, and that the source loci of MMN and N1 are different. Contradicting these findings, our combined electromagnetic, hemodynamic, and psychophysical data indicate that the MMN is generated as a result of differential adaptation of anterior and posterior auditory cortex N1 sources by preceding auditory stimulation. Early ( approximately 85 ms) neural activity within posterior auditory cortex is adapted as sound novelty decreases. This alters the center of gravity of electromagnetic N1 source activity, creating an illusory difference between N1 and MMN source loci when estimated by using equivalent current dipole fits. Further, our electroencephalography data show a robust MMN after a single standard event when the interval between two consecutive novel sounds is kept invariant. Our converging findings suggest that transient adaptation of feature-specific neurons within human posterior auditory cortex filters superfluous sounds from entering one's awareness.

Adult↗
PubMed1988

Accessory pathway for sound transfer in a neotropical frog.

A portion of the lateral body wall overlying the lung cavity of the arboreal frog, Eleutherodactylus coqui, vibrates in response to free-field sound. Peak displacement amplitude of the body wall in response to a natural call note presented at 73 decibels sound pressure level is 1.70 X 10(-9) m, roughly 8 decibels less than that of the ipsilateral eardrum, as measured by laser Doppler vibrometry. We show that the vibration magnitude varies predictably across the body profile and is posture and frequency dependent. Two routes to the inner ear are described for sounds impinging on the body wall; either of these accessory pathways could modify direct input from the peripheral auditory system and enhance sound localization in these small vertebrates.

Animals↗