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At least 1,189 records · Page 66Linked to original sources
PubMed1992

Vibro-acoustic stimulation does not alter the duration of high and low fetal heart rate variability episodes.

To study the effect of vibro-acoustic stimulation on high and low fetal heart rate (FHR) variability episodes. Prospective control study, in 21 high risk pregnancies between 32 to 39 weeks gestation. FHR pattern was recorded with cardiotocograph (CTG). After 5 min low FHR variability a vibro-acoustic stimulator was activated in contact with or above the maternal abdomen (sham) on a random basis on two consecutive days, and CTG was continued to obtain a complete high and low FHR variability cycle. Complete high and low FHR variability cycles were obtained in 12 patients with mean recording time of 129.5 minutes (range 69-185 min). The mean baseline FHR increased by 32.5 +/- 9.4 bpm after contact vibro-acoustic stimulation, but remained unchanged after sham stimulation. Mean duration of high FHR variability was 56.6 +/- 32.9 min and 47.3 +/- 23.7 min, respectively, and mean duration of the consecutive low FHR variability episode was similar after contact and sham stimulation. The complete cycles were 71.1 +/- 34.7 min and 66.2 +/- 21.2 min, respectively. Vibro-acoustic stimulation induced an abrupt change from low to high FHR variability, but the complete cycle of high and low FHR variability was not altered, when compared with the corresponding cycle following sham stimulation on the same fetus.

Acoustic Stimulation↗
PubMed2004

An acoustic study of the temporal characteristics of nasalization in children with and without cleft palate.

OBJECTIVE: The purpose of this study was to measure the oral and nasal cavity acoustic energies to determine whether temporal patterns of nasalization differentiate children with and without cleft palate and the extent to which vowel context contributes to these temporal differences. DESIGN: Nasal onset interval, nasal offset interval, and total nasalization duration measures were obtained from acoustic waveforms, spectrograms, and energy contours acquired using the Computerized Speech Lab (Kay Elemetrics, Lincoln Park, NJ). In addition to absolute temporal values, proportional durations of nasalization were measured to obtain information regarding the relative duration of nasalization. PARTICIPANTS: Fifteen children with cleft palate exhibiting mild hypernasality and 15 children without cleft palate participated in the study. Children in both groups were between 4 and 7 years of age. RESULTS: Each of the three absolute measures was significantly different between the two groups of subjects and within the three vowel contexts. Children with cleft palate showed longer temporal characteristics than children without cleft palate in all three absolute measures. The three temporal variables of the high vowel contexts were generally longer than those of low vowel contexts. Regarding proportional measures, nasal offset interval ratio, and total nasalization ratio showed significant differences between the two groups. CONCLUSIONS: Nasalization, as reflected by acoustic signals, showed different timing characteristics between children with cleft palate and without cleft palate and across vowel contexts. This suggests that the duration of nasalization reflecting temporal patterns of the oral-nasal acoustic impedance may have an influence on the perception of hypernasality.

Analysis of Variance↗
PubMed2002

Acoustic detection of termite infestations in urban trees.

A portable, low-frequency acoustic system was used to detect termite infestations in urban trees. The likelihood of infestation was rated independently by a computer program and an experienced listener that distinguished insect sounds from background noises. Because soil is a good insulator, termite sounds could be detected easily underneath infested trees, despite the presence of high urban background noise. Termite sounds could be detected also in trunks, but background noise often made it difficult to identify termite signals unambiguously. High likelihoods of termite infestation were predicted at four live oak (Quercus virginiana Mill, Fagacae), two loblolly pine (Pinus taeda L., Pinacae), and two baldcypress (Taxodium distichum Rich. Pinacae) trees that wood-baited traps had identified as infested with Coptotermes formosanus Shiraki. Infestations also were predicted at two pine trees with confirmed recoveries of Reticulitermes flavipes (Kollar). Low likelihoods of infestation were predicted in four oak trees where no termites were found. Additional tests were conducted in anechoic environments to determine the range of acoustic detectability and the feasibility of acoustically estimating termite population levels. There was a significant regression between the activity rate and the number of termites present in a wood trap block, with a minimum detectable number of approximately 50 workers per liter of wood. The success of these field tests suggests that currently available acoustic systems have considerable potential to detect and monitor hidden infestations of termites in urban trees and around building perimeters in addition to their present uses to detect and monitor termite infestations in buildings.

Acoustics↗
PubMed2003

Involvement of poly(ADP-ribose) synthetase in acoustic trauma of the cochlea.

We investigated effects of poly(ADP-ribose) synthetase (PARS) inhibitors on acoustic trauma. Albino guinea pigs were intravenously given 3-aminobenzamide, nicotinamide or 3-aminobenzoic acid (an inactive analog of 3-aminobenzamide) just prior to exposure to a 2 kHz pure tone of 120 dB sound pressure level (SPL) for 10 minutes. The threshold of the compound action potential (CAP) and the amplitude of distortion-product otoacoustic emissions (DPOAEs) were measured before and 4 hours after the acoustic overexposure. Statistically significant decreases in the CAP threshold shifts and significant increases in the DPOAE amplitudes were observed 4 hours after the acoustic overexposure in the animals treated with 3-aminobenzamide or nicotinamide, whereas 3-aminobenzoic acid did not exert any protective effect. These results strongly suggest that excessive activation of PARS is involved in generation of the acoustic trauma.

Acoustic Stimulation↗
PubMedDate not supplied

Contralateral acoustic suppression of transient evoked otoacoustic emissions--activation of the medial olivocochlear system.

Medial olivocochlear pathway represents the final part of efferent acoustic pathway which comes from the superior olivary complex ending at outer hair cells. Activation of medial olivocochlear system (MOCS) alters the cochlear output decreasing the travelling wave within cochlea. Stimulation of MOCS provides protection against moderate levels of noise, encoding noise signals as well as selecting hearing attention. Activation of MOCS can be performed using contralateral acoustic stimulation. The principal result of presentation of contralateral acoustic stimulation during screening of transient evoked otoacoustic emission (TEOAE) is an attenuation of the TEOAE amplitude. Thirty-eight ears were examined in this study: twenty-eight ears from 14 normal-hearing adults and 10 patients with unilateral deafness. Healthy subjects were exposed to contralateral broad-band noise of various intensities (40, 30, 20 and 10 dB SL), as well as 30 dB SL pure tone stimulation (1 kHz and 4 kHz). A decrease of TEOAE amplitudes during contralateral stimulation with 40 and 30 dB SL broad-band noise and pure tones was established. This effect was a result of MOCS activation. A greater intensity of contralateral stimulation evoked greater decrease of TEOAE amplitude; stimulation with broad-band noise caused greater attenuation than with pure tone stimulation. Contralateral stimulation of deaf ears in the group with unilateral deafness was also performed. Statistically significant difference between TEOAE amplitude before and during contralateral stimulation was not established. This circumstance explains that activation of MOCS and consequent reduction of outer hair cells motility is very possibly caused by contralateral acoustic stimulation. Apart from studying physiological significance of efferent auditory system, results of this and similar studies can be used for production of hearing aids improving speech discrimination in noisy environment.

Acoustic Stimulation↗
PubMedDate not supplied

Nasal patency measured by acoustic rhinometry in East Asian patients with sleep-disordered breathing.

BACKGROUND: Nasal obstruction is thought to be a risk factor in obstructive sleep apnea (OSA). However, the relationship between nasal patency and sleep-disordered breathing remains controversial. The aim of this study was to examine the association between acoustic rhinometry findings and results of overnight polysomnography. METHODS: From February to October 2003, patients who underwent overnight polysomnography assessment were enrolled in the study. We excluded patients who were under 20 years old, had severe deviated nasal septum, had previously received nasal or palatal surgery, or could not complete sleep test or acoustic rhinometry examination. Participants' basic data including age, gender, neck circumference, and body mass index (BMI) were collected. All participants received acoustic rhinometry before overnight polysomnography. The results along with sleep-test outcomes were recorded and analyzed. RESULTS: A total of 87 patients were included in this study. Patients with respiratory disturbance index (RDI) less than 5/h (n = 26) or with RDI of 5-30/h (n = 28) tended to have larger minimal cross-sectional area (MCA) compared with those of patients whose RDI was more than 30/h (n = 33) (P = 0.001). A stepwise multiple regression analysis showed that BMI, male gender, and MCA were contributing factors in RDI. The R2 value of the multiple regression analysis was 0.406. CONCLUSION: Patients with severe OSA tended to have smaller MCA when compared with patients with RDI less than 30/h. However, it was hard to predict whether patients had OSA from acoustic rhinometry examination.

Adult↗
PubMedDate not supplied

Physiological change in nasal patency in response to changes in posture, temperature, and humidity measured by acoustic rhinometry.

BACKGROUND: Acoustic rhinometry has been used to assess nasal patency and to calculate nasal cavity volume. This study used acoustic rhinometry to assess changes in nasal patency after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. METHODS: Eight healthy adult volunteer subjects underwent acoustic rhinometry during the following conditions: (1) sitting position (control), (2) supine position, (3) left lateral recumbent position, (4) nostril unilaterally mechanically blocked, (5) ice pack on neck, (6) drinking cold water, (7) drinking hot water, (8) nasal nebulizer, and (9) oxymetazoline decongestant. RESULTS: Two distinct patterns emerged based on the total nasal cavity volumes in response to the decongestant. Subjects with initial unilateral nasal cavity volumes near the mean had an expected increase in total volume after the topical decongestant administration. There were two subjects with initial volumes of 1 SD above the mean that had a paradoxical decrease in total volume in response to the decongestant. In all subjects, there was a significant decrease in the volume of each of the nasal cavities in response to ingestion of hot water at 1 minute. There was a significant decrease in the volume of the smaller of the two nasal cavities in response to nebulizer treatment and hot water ingestion at 5 minutes. Total nasal cavity volume changes were not significant for any of the variables. CONCLUSION: Changes in nasal cavity volumes were detected by acoustic rhinometry after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. Nebulizer treatment and hot water ingestion caused a significant decrease in nasal volume. The nose of a healthy patient was able to adapt to environmental and physiological changes to maintain a consistent total nasal volume within 15 minutes.

Adult↗
PubMedDate not supplied

Patient-specific cell-mediated immunity against human acoustic neuroma extract.

Lymphocytes from 8 patients with acoustic neuromas and 8 healthy control persons were exposed to acoustic neuroma extract. Indirect leukocyte migration agarose technique was applied for detection of leukocyte migration inhibition (LMI). The standard technique was additionally modified using a specific assay for release of human leukocyte migration inhibitory factor (LIF). Both the standard technique and the LIF-specific assay revealed a significant LMI exerted by lymphocytes from patients, as compared with control persons. The LIF-specific assay demonstrates that the LMI is an expression of cell-mediated immunity due to release of LIF. The immune reaction is raised against an unknown antigen in acoustic neuroma extract. Further studies must determine whether the immune reaction is specific for acoustic neuroma patients vis-a-vis patients with other tumours, especially other neuromas.

Adult↗
PubMedDate not supplied

Antigenicity and protein content of perilymph in acoustic neuroma patients.

11 acoustic neuroma patients, exhibiting cell-mediated immunity in vitro against acoustic neuroma extract, were tested for cell-mediated immunity in vitro against perilymph samples from other acoustic neuroma patients. 14 of 21 perilymph samples were antigenic. None of three healthy persons reacted against antigenic perilymph samples. The perilymph antigenicity was reproducible and negatively correlated to the perilymph sample volume. Differences in sample volume could not be ascribed to admixture of endolymph, cerebrospinal fluid, plasma or blood. The perilymph protein concentration varied from 31 to 54 g/l. Gel electrophoresis of perilymph proteins revealed less staining in the alpha-region compared to plasma proteins and a distinct band in the pre-gamma region absent in plasma. Tau-transferrin was not detected in any of 13 samples. The findings support that the cell-mediated immune response against acoustic neuroma extract may be mediated through release of antigen(s) to the perilymph.

Adolescent↗
PubMed1991

Acoustic neuromas presenting as sudden hearing loss.

Progressive hearing loss is well known as a usually existing complaint in patients with acoustic neuromas. However, sudden hearing loss is also a relatively frequent condition in acoustic neuroma patients. In our review of 132 patients with surgically proven unilateral acoustic neuromas, 29 (22.0%) presented a history of sudden hearing loss. We investigated the clinical and audiological characteristics of these patients, and discuss the etiology of sudden hearing loss in patients with acoustic neuromas. The characteristics of patients with AN presenting sudden hearing loss were as follows: 1) a small tumor, 2) short duration after onset, 3) low incidences of vertigo, dizziness, facial and trigeminal nerve symptoms, 4) the trough type in the audiogram configuration, 5) normal caloric response. Based on the analysis of these results, we conclude that a conduction block of the cochlear nerve is likely to be the etiology of sudden hearing loss.

Adult↗
PubMed1991

Usefulness of acoustic studies on the differential diagnostics of organic and functional dysphonia.

Phoniatric and acoustic examinations were carried out in a group of 30 patients with dysphonia, including 15 with organic type and 15 with functional type. A complex phoniatric assessment offered the possibility to differentiate between these two groups of pathological voices. This was achieved also on the basis of acoustic analysis of the voice by extracting characteristics such as: formant frequency, Fo and its range, percentage of noise in the analysed verbal text, mean and maximum values of jitter. The possibility of differential diagnosis of these two different types of dysphonia in acoustic studies was confirmed by clinical examinations. The acoustic studies presented can be regarded as a new approach to a fast and sufficiently precise method in the screening diagnostics of dysphonia conditioned by growth of the vocal fold mass.

Diagnosis, Differential↗
PubMed1992

A randomized, double-blind, placebo-controlled study of dextran/pentoxifylline medication in acute acoustic trauma and sudden hearing loss.

The effectiveness of any therapy in acute acoustic trauma or sudden hearing loss of unknown origin has not been demonstrated convincingly. The assessment is difficult because of a relatively high rate of spontaneous recovery. Nevertheless, many different forms of treatment are recommended. We tested one form, treatment with rheoactive substances, in a prospective, randomized, double-blind trial and compared treatment with (a) infusions of dextran-40 with pentoxifylline, (b) saline infusions with pentoxifylline, and (c) saline infusions with placebo medication. Pure-tone hearing thresholds served as control parameters and were taken before treatment and at 1 and 4 weeks after the onset of therapy. Three hundred eighty-two patients were included in the trial, 331 (87%) could be analyzed, 184 patients were treated because of sudden hearing loss, 147 because of acute acoustic trauma. The three treatment groups were comparable in their basic characteristics including the amount of initial hearing loss. In patients with sudden hearing loss, no significant differences of hearing recovery were detected between the three treatment groups. Hearing recovery was also similar in patients with acute acoustic trauma. A power analysis of the study revealed that possible true treatment differences of a hearing recovery of 10 dB would have lead to significance with a probability of over 90%. It is concluded that there were, in fact, no clinically relevant differences in hearing gains of sudden hearing loss or acute acoustic trauma between treatments with saline infusions together with placebo medication and treatment with dextran-40 and/or pentoxifylline.

Acoustic Stimulation↗
PubMed1994

Experimental studies of the resolution of acoustic rhinometry in vivo.

The ability of acoustic rhinometry to detect objects of defined size in nasal cavities has hitherto been investigated only in cadavers and models. We aimed to determine the resolution of the technique in the nose of living subjects. Silicone spheres of 3.0, 5.0, and 7.0 mm diameter were placed at two sites in the decongested and locally anaesthetised nasal cavities of 3 healthy adults. Acoustic rhinometry area-distance functions were obtained before and after insertion of the spheres, with further control data obtained after removal of the sphere from the nasal cavity. Six nasal cavities were studied in each test state on two separate occasions. The 3.0 mm sphere caused a statistically significant change in cavity volumes in only 17% of cases when placed in the middle meatus and in 8% at the nasal value (Mann-Whitney U-test; p < 0.05). The detection rates for the 5.0 mm sphere were 50% in the middle meatus and 50% at the nasal valve. When the control and test curves were compared by superimposition and the cross-sectional areas at the site of perturbations compared statistically (Mann-Whitney U-test) the detection rates in the middle meatus were: 33%-3.0 mm and 67%-5.0 mm sphere. The detection rate at the nasal valve region was 25%-3.0 mm sphere and 58%-5.0 mm. The 7.0 mm sphere was detected in 100% cases by volume changes, and 80% by area changes. Acoustic rhinometry can reliably detect changes of volume and area in the living nose resulting from the introduction of a 7 mm sphere into the nasal valve or middle meatal region in most cases. Smaller spheres are detected in only a fraction of cases. The resolution of the technique is therefore close to 7.0 mm (1.44 cm3). These findings are important when interpreting acoustic rhinometry data in monitoring patients with nasal pathology.

Acoustics↗
PubMed1980

Attention, eye closure and the acoustic reflex.

The first part of this study considered the effects of differing states of attention on the acoustic reflex response. Tasks directing attention towards and away from the acoustic stimuli were compared with a neutral task. A significant reduction in reflex response magnitude was associated with the task directing attention away from the stimulus. The stimulus-directing task did not significantly affect the acoustic reflex response. The second part of the study investigated the effect of eye closure on the acoustic reflex response. The results showed an increase in reflex response magnitude with eye closure but not with darkness alone. This implied that the increase was associated with the muscular effort involved in eye closure.

Adult↗
PubMed1996

Acoustic reflex monitoring during the presentation of 1000 clicks at high repetition rates.

This study was designed to monitor acoustic reflexes during the type of stimulation used in the auditory brainstem measures. Twenty normal female subjects within the age range 20 to 26 years participated in the study. The probe tone frequency was 226 Hz and the intensity was 85 dB SPL. Approximately 1000 clicks were presented to the right ear through an insert earphone and acoustic reflexes were monitored in the left ear. The clicks were presented at 95 and 105 dB peSPL and at 50 and 100/sec rates. At the rate of 50/sec, the acoustic reflex was present in 70% of the subjects at 95 dB peSPL and in 85% of the subjects at 105 dB peSPL. At the rate of 100/sec, the reflex was present in 80% of the subjects at 95 dB peSPL and in 95% of the subjects at 105 dB peSPL. The ANOVA on the acoustic reflex amplitudes showed an increase in the amplitudes with an increase in the click rates and levels.

Adult↗
PubMed1991

Evaluation of click-evoked oto-acoustic emissions in the newborn.

Click-evoked oto-acoustic emissions and auditory brainstem responses (ABR) have been recorded in 723 babies taken largely from a neonatal intensive care unit to evaluate the use of oto-acoustic emissions as a method of screening for hearing impairment. Twenty-nine infants failed to pass the initial ABR test and repeat ABR tests carried out up to the age of 3 months. The 'sensitivity' and 'specificity' of the oto-acoustic emission test for the ABR test results up to 3 months of age in surviving infants were 93% and 84% respectively. It is proposed that click-evoked oto-acoustic emissions be considered as the initial method to screen for hearing impairment, test failures being followed up by ABR.

Acoustic Stimulation↗
PubMed1985

Preservation of hearing in patients undergoing excision of acoustic neuromas and other cerebellopontine angle tumors.

Microsurgical techniques have made it possible to identify and preserve the cochlear nerve from its origin at the brain stem and along its course through the internal auditory canal in patients undergoing removal of small or medium-sized acoustic neuromas or other cerebellopontine angle (CPA) tumors. In a consecutive series of 100 patients with such tumors operated on between 1975 and 1981, an attempt was made to preserve the cochlear nerve in 23. The decision to attempt to preserve hearing was based on tumor size and the degree of associated hearing loss. In cases of unilateral acoustic neuroma, the criteria for attempted preservation of hearing were tumor size (2.5 cm or less), speech reception threshold (50 dB or less), and speech discrimination score (60% or greater). In patients with bilateral acoustic neuromas or tumors of other types, the size and hearing criteria were significantly broadened. All patients were operated on through a suboccipital approach. Hearing was preserved postoperatively in six (31.6%) of the 19 patients with unilateral acoustic neuromas, although the cochlear nerve was preserved in 16. Of the six patients with postoperative hearing, three retained excellent hearing, and the other three had only sound awareness and poor discrimination. Hearing was preserved in three cases with other CPA tumors, including an epidermoid cyst and small petrous meningiomas in the internal auditory canal. Of the two cases with bilateral tumors, hearing was preserved in one. Of the 23 patients in whom hearing preservation was attempted, nine (39.1%) had some postoperative hearing, which in six was equal to or better than the preoperative level. Thus, it is worthwhile to attempt hearing preservation in selected patients with CPA tumors.

Brain Neoplasms↗
PubMed1993

Intracanalicular acoustic neuroma: early surgery for preservation of hearing.

Diagnosis of very small acoustic neuromas has become much more common since the advent of magnetic resonance imaging. Many of the patients so diagnosed have minimal unilateral hearing loss as their only symptom. Because limited information is available on the natural history and prognosis of these lesions, the choice of treatment is controversial. The authors review their recent experience with the surgical treatment of intracanalicular acoustic neuroma. The records of 14 consecutive patients with intracanalicular acoustic neuroma were reviewed with respect to type of presentation, pre- and postoperative facial and auditory nerve function, surgical approach, and complications. Detailed results for patients operated on to preserve hearing are presented. Presenting symptoms were nearly equally divided among diminished hearing, vertigo, and tinnitus. Eleven of the 14 patients had serviceable hearing preoperatively and nine (82%) remained in this condition postoperatively. Facial nerve function was unchanged by operation in 12 patients. Seven operations were performed through the middle fossa, five through the posterior fossa, and two by the translabyrinthine approach. The probability of preserving hearing during surgical excision of intracanalicular acoustic neuroma in patients with serviceable hearing exceeds 80%. Given the relative infrequency of serious complications and the likelihood of progressive hearing loss in the untreated patient, excision of such small tumors shortly after diagnosis may offer the best chance of long-term hearing preservation.

Adult↗