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PubMed1997

Combined effect of noise and vibration on articulation of Chinese syllable.

To study combined effect of noise and vibration on articulation, changes of the speech features of Chinese single syllabic utterances were investigated under combined factors. The experiments were conducted under four conditions: combined noise and vibration, simple noise, simple vibration and control. A set of signal processing system was established, programs for speech signal analysis and statistics were developed. The results showed that, as compared with simple noise , simple vibration or control condition, the fundamental frequency, energy and duration of articulation under combined conditions increased significantly. It suggests that the effect of noise and vibration should be considered in the design of aerospace speech recognition system.

Aerospace Medicine↗
PubMedDate not supplied

Vibration sense testing with a 128-Hz tuning fork as a tool to determine recovery from epidural neuraxial block.

BACKGROUND AND OBJECTIVES: Vibration sense testing using a 128-Hz tuning fork is a commonly used test in the diagnosis of dorsal horn dysfunction and polyneuropathy. In this open, prospective study, we tested the hypothesis that vibration sense testing is a sensitive and specific method to assess recovery from epidural block. METHODS: Recovery from epidural block was evaluated in 81 patients undergoing cesarean delivery or vein stripping by comparing the use of a 128-Hz tuning fork with the results of conventional evaluation of block recovery. Conventional block recovery testing included Bromage-Score, formal muscle power testing according to the British Medical Research Council, pinprick testing, and warm/cold testing. Epidural blocks were performed by the same anesthesiologist using ropivacaine and sufentanil via an epidural catheter. After obtaining baseline values, an epidural anesthetic was performed and patients were tested every 30 minutes until complete recovery from the block was documented with all examined methods. Statistical analysis was performed to compare the results of the different methods to the time at which baseline values of vibration sense were reached. RESULTS: At the time vibration sense testing returned to baseline, there was no residual motor block according to the Bromage Score in 100% of the patients and no residual block for foot flexion and extension. Twelve percent of the patients showed a minimal lack of strength in the quadriceps muscle and 11% had residual sensory anesthesia to pinprick below L5/S1. CONCLUSIONS: Based on our observations, recovery of vibration sense corresponds with recovery of motor block after epidural anesthesia and may serve as an easy means of documenting recovery with a single test before discharge.

Adult↗
PubMed2001

Vascular and nerve disorders at exposure to hand-held vibrating tools related to ISO 5349.

The authors present the results of the investigation of peripheral nerves of the hand in a group of 30 glass cutters, 21 metal grinders, 10 blacksmiths and 24 workers who worked with nailers. The measurements of vibrotactile sensitivity were carried out by Vibrometry System Brüel & Kjaer Type 9627. The vibrotactile perception thresholds (VPT) were measured in frequency range from 8 to 500 Hz. The same investigations were carried out in 103 healthy subjects with no previous work-exposure to vibration or shocks. Further electromyographic examination was carried out in all members of exposed groups. The results of measurements VPT have proved reliability and high sensitivity of this method for the early detection of light disorders of peripheral nerves of the hand due to vibration. All the workers also passed investigation of vascular system of fingers. Simultaneously the measurement of vibration and shocks of single types of hand-held tools used by workers was done. The results of measurement have been worked up according to ISO 5349 (1) that enables to determine the beginning of the incidence of disorders of the hands and arms on the base of measured values of vibration and shocks. The results of the vascular system investigation have been compared with the results of the assessment of exposure according to ISO 5349. The conformity has been proved in the case of hand-transmitted vibrations not in the case of shocks.

Case-Control Studies↗
PubMed2002

The effects of timing and application of vibration on muscular contractions.

BACKGROUND: The effect of vibration stimulation on muscular strength is an emerging field of research and very little comprehensive work has been conducted at this stage. HYPOTHESIS: There will be no effects of timing or application of vibration stimulation on muscular strength and activation across isometric, isokinetic and concentric isotonic contractions. METHODS: There were 28 recreational athletes who participated in this study. Their characteristics were: (mean +/- SD) age, 22.8 +/- 5.6 yr; height, 174.1 +/- 8.8 cm; and body mass, 78.0 +/- 13.6 kg. The vibration stimulation was delivered at 50.42 +/- 1.16 Hz with an acceleration of 13.24 +/- 0.18 ms(-2). RESULTS: A series of one-way ANOVAs revealed significant (p < 0.05) improvements of 14.7 +/- 2.9% and 15.3 +/- 3.1% above normal contraction levels for concentric isotonic strength during and after the vibration stimulation, respectively. No significant improvements in isometric and isokinetic strength were evident. Concurrent measurement of electromyography (EMG) presented significant improvements during stimulation of 30.1 +/- 14.6%, 43.0 +/- 13.0%, and 107.1 +/- 44.4% in mean activation of rectus femoris (RF) for the isometric, isokinetic, and concentric isotonic contractions, respectively. Synchronous collection of vibromyography (VMG) during stimulation displayed a significant decrease of -6.4 +/- 1.5%, -5.1 +/- 1.2%, and -4.1 +/- 1.7% in mean VMG activity of RF for the isometric, isokinetic, and concentric isotonic contractions, respectively. CONCLUSIONS: Significant improvements in muscular strength and activation for concentric isotonic contractions performed during an applied vibration suggest that the optimal timing of a vibratory stimulation would be while the participant is contracting isotonically. However, further research needs to be conducted to establish the exact mechanism behind these improvements.

Adolescent↗
PubMed2000

[Effects of nitroprusside and vibration on peritoneal transport of solutes in continuous ambulatory peritoneal dialysis patients].

To explore the relationship between peritoneal transport of solutes and permeability of the peritoneum capillary as well as peritoneal stagnant fluid layer within dwell time, we observed the effects of nitroprusside and vibration on peritoneal transport of solutes in continuous ambulatory peritoneal dialysis(CAPD) patients. Twelve stable, routine CAPD patients were involved, who had no peritonitis for at least 4 weeks before the test. Standard peritoneal equilibrium tests(PETs) were performed, and mass transfer area coefficiency(MTAC) were calculated after adding nitroprusside to the dialysate or vibrating the patients's peritoneum. The concentrations of total protein, albumin and immunity globulin G in total drained dialysate were examined, and total drained volumes were recorded. Compared with the control, the MTACs value of BUN, Creatinine(Cr) increased significantly both in the nitroprusside group and vibration group(P < 0.05); the concentration of immunoglobin G in the total drained fluid was higher in the nitroprusside group than that in the control(P < 0.05); However, there was no significant difference in the total drained volume among the three groups. We conclude that nitroprusside and vibration can increase the peritoneal transport of small molecular solutes, and vibration has less influence on the loss of protein in CAPD. It suggests that moderated movement may improve the removal of the small molecules in CAPD patients.

Adult↗
PubMed2003

Vibration induced nystagmus in normal subjects and in patients with dizziness. A videonystagmography study.

OBJECTIVE: To analyze the incidence and characteristics of vibration-induced nystagmus in normal subjects and in patients with vertigo. STUDY DESIGN AND SETTING: This is a prospective analysis of the effect of vibration on several points of the skull in 38 normal subjects, 10 patients who had undergone labyrinthectomy and 125 consecutive patients with dizziness referred to a tertiary care center. Nystagmus was documented and its corresponding slow phase velocity measured with a videonystagmography system. RESULTS: In 81.6% of normal subjects and 80.8% of all patients, nystagmus could be provoked by stimulation of at least one of the points on the skull to which the vibrator was applied. In normals, however, no subject had nystagmus greater than 2.8 degrees s-1 whereas 35.2% of patients did. CONCLUSION/SIGNIFICANCE: The value of the slow-phase velocity of vibration-induced nystagmus can be used to identify a sizeable proportion of patients with a vestibular disorders. Vibration-induced nystagmus is a frequent sign in patients with dizziness and can provide complimentary information about vestibular system function.

Adult↗
PubMed2004

Cockpit seat and pilot helmet vibration during flight operations on aircraft carriers.

INTRODUCTION: Human vibration exposure data relative to military tactical and strategic aircraft operations are required for assessing the potential health risks and performance consequences when using helmet-mounted equipment. The objective of this study was to characterize cockpit seat and pilot helmet vibration in a jet aircraft during aircraft carrier flight operations. METHODS: The Remote Vibration Environment Recorder (REVER) was used to measure triaxial accelerations at the seat base, seat pan, seat back, and helmet in the F/A-18C (Hornet) jet aircraft. Data were collected during flight operations on 2 aircraft carriers for a total of 11 catapult launches (CATs), 9 touch-and-goes (TGs), and 4 arrested landings (TRAPs). Helmet pitch acceleration and displacement were estimated from the helmet translational acceleration data. RESULTS: Of particular interest was the substantial low frequency seat and helmet vibration observed during the catapult launch. During the stroke period, seat and helmet vertical (Z) accelerations reached 6 and 8 g peak-to-peak, respectively, and occurred in the frequency range of 3-3.5 Hz. The associated helmet pitch reached peak-to-peak displacements ranging between 90 and 18 degrees. DISCUSSION: The large helmet rotations may be associated with helmet slippage that can cause partial or complete loss of the projected image on a helmet-mounted display (HMD) (vignetting). This is highly undesirable when using the HMD as the primary flight reference. The aircraft operational vibration can be regenerated in the laboratory for investigating this specific concern. The goal is to develop helmet-mounted equipment design guidelines that consider hostile vibratory environments.

Aerospace Medicine↗
PubMed2004

Back muscle EMG of helicopter pilots in flight: effects of fatigue, vibration, and posture.

INTRODUCTION: The high prevalence of low back pain in helicopter pilots has been attributed to back muscle fatigue due to a pilot's required posture and/or aircraft vibration. This study investigated the effect of posture and vibration on the surface electromyogram (EMG) of right and left erector spinae (ES) muscles of pilots and evaluated ES fatigue during flight. METHODS: There were 12 male pilots who were monitored during helicopter flights lasting an average of 2 h. Prior to the flight, a maximal voluntary contraction (MVC) of ES was performed and the EMG was recorded. Vibration was measured at the pilot's seat through a triaxial accelerometer. The effect of posture on EMG was tested by comparing four characteristics of left and right EMG expressed as % MVC. Effect of Z vibration on EMG was investigated by coherence function and through correlation between coherently averaged EMG and Z for the frequencies of the main rotor of the helicopter (1R) and its first harmonic (2R). Fatigue was investigated through median frequencies (MF) of the EMG power spectra. RESULTS: No effect of posture on EMG was found for any parameter (p > 0.05). Data from one pilot suggested an effect of 1R on EMG, but statistical tests revealed this not to be significant (p > 0.05) for any pilot. No fatigue was evidenced by linear regression of MF. CONCLUSION: While the scientific literature contains the hypothesis that low back pain in helicopter pilots is mainly due to muscle fatigue caused by posture and/or vibration, the present study did not lend support to this hypothesis.

Acceleration↗
PubMed2004

[Vibration risk during neonatal transport].

AIM: The aim of this paper is to assess the entity of the mechanical vibrations which newborn and medical staff are exposed to and to evaluate the possible risks connected with excessive exposure. METHODS: Vibrations during a simulated emergency ambulance transport were studied. Vibration values with an accelerometer at the level of the incubator's mattress and at passengers' and pilot's seat level were measured. Mean accelerations (awz) and peak accelerations (awpeak), measured using a ponderation filter, according with ISO standard 2631, were considered. RESULTS: Inside the incubator an acceleration mean value of 1.33 (+/-0.13) m/s(2) and peak values of 11.8 (+/-0.1) m/s(2) were found. On passengers' seats the awz findings were 0.55 m/s(2) (+/-0.13) and 0.56 m/s(2) (+/-0.08) while awpeak respectively 4.8 m/s(2) (+/-0.1) and 10.2 m/s(2) (+/-0.1). On pilot's seat a mean acceleration of 0.48 m/s(2) (+/-0.08) and an awpeak value of 4.5 m/s(2) (+/-0.1) were found. CONCLUSION: Peak vibration values which newborns are exposed to (11.8 m/s(2)) are high, when compared with acceleration of gravity (9.8 m/s(2)); this can provoke repeated jerks. Environmental stress can easily alter the stability of an ill newborn and interfere with care manoeuvres. Decreasing vibrations in neonatal transport unit could increase the safety of newborns, reducing the risks which newborns are actually exposed to.

Humans↗
PubMed2004

Dentinal crack incidence following ultrasonic vibration to intra-radicular posts.

OBJECTIVE: To determine the incidence of dentinal cracks on the root-face of extracted teeth containing intra-radicular posts subjected to prolonged ultrasonic vibration. Design & Setting This in-vitro experiment, conducted at the University of Manchester, UK, used post type and ultrasonic vibration as dependent variables. MATERIALS AND METHODS: Forty canine teeth were decoronated and root-filled with gutta-percha and sealer. A parallel shaped post-space of 1.4 mm diameter and 10 mm depth was prepared in each root. The teeth were grouped into morphologically similar pairs, and for each pair one tooth was randomly allocated to receive a zirconium ceramic post, the other a stainless steel post. The pairs of teeth were randomly assigned to a control or to a test group. The root-face was examined for dentine cracks or fractures with direct vision and at 20x magnification with transillumination. Samples were then stored in sterile water for one week. Ultrasonic vibration was applied continuously for 30 minutes to the top of the posts in the test groups. All samples were then re-examined for dentine cracks or fractures. RESULTS: Following storage, no new cracks were evident for the control groups. Seven new cracks occurred in the test groups (following application of ultrasonic vibration), six of which were on the root-face of samples with ceramic posts. The difference in crack distribution between the two groups was significant (Fisher's Exact Test, p=0.029). CONCLUSION: Prolonged application of ultrasonic vibration to ceramic posts increased the incidence of root-face cracks.

Ceramics↗
PubMed2003

Effects of vibration, feed force and exposure duration on operators performing drilling task.

It has been shown that vibration level, feed force, and exposure duration cause unfavourable effects on the work performance when hand-held vibrating tools are used by operators. Present study analyzed the effects of these variables on the heart rate and blood pressure of the operators carrying out the drilling task. Under three different levels of vibration (0.3, 0.5, and 1 m/s2), the operators performed the drilling for 3 minutes with three different levels of feed force (100, 200, and 300 N) in study 1, and for three different durations (10, 15, and 20 min) with a feed force of 200 N in study 2. Thirty male subjects participated in the two studies and data were analyzed on the basis of two factor repeated measure kind of experimental design. Results showed that in the kind of drilling task undertaken the level of vibration was statistically significant. However, the main effects of feed force and vibration exposure duration were statistically insignificant. These findings are discussed in the light of previous researches conducted on the subject.

Adult↗
PubMed2006

[Clinical features of the hand-arm vibration syndrome in miners].

INTRODUCTION: It is well known that the vibrating tools used by the miners can cause hand-arm vibration syndrome. However no detailed reports on this field could be found in the Hungarian literature. AIM: The aim of this study was to clarify the clinical features of the hand-arm vibration syndrome of the miners. METHOD: The circulation, the peripheral nerves and the osteoarticular system of the upper extremities of 152 miners were examined by means of cold provocation test, Allen-test, measurement of systolic blood pressure performed by Doppler flowmeter, clinical neurological and neurographic examination and X-ray investigation of the bones and joints. RESULTS: Hand-arm vibration syndrome was diagnosed in 87 patients (57.2%). The most common symptom was the lesion of the circulation which occurred in 78 patients (89.6%). The peripheral nerves were affected in 44 cases (50.5%). Radiological alteration of the bones and joints of the upper extremities was observed in 32 patients (36.8%). Out of 78 damaged cases the frequency of the vascular diseases was as follows: angiopathy (diminished systolic blood pressure in the fingers): 66 patient (84.6%), occlusion of the hand arteries (positive Allen-test) and arterial form of the thoracic outlet syndrome (positive elevation-test) respectively: 28 and 28 cases (35.9%), Raynaud phenomenon (positive cold-provocation test): 26 cases (33.3%). The peripheral nerves were examined in detail in 141 cases. Pathological alterations were observed in 78 patients (55.3%) in the following forms: carpal tunnel syndrome: 66 cases (84.6%), peripheral neuropathy of the upper limbs: 20 patients (25.6%), lesion of the ulnar nerve: 3 cases (3.8%), brachial plexus lesion: one patient (1.3%). Radiological alteration was most common in the carpal region (87 cases, 57.2%). The frequency of the lesion of cubital (40.4%) and shoulder region (40.7%) was practically the same. In the carpal region the most common alterations were the degenerative processes (23 cases, 15.1%) followed by the aseptic osteonecroses (22 patients, 14.5%). In the cubital region the periarticular changes (31 patients, 23.9%) were most common followed by degenerative changes (21 cases, 16.2%) and the osteochondrosis dissecans (13 cases, 10.1%). In the shoulder region the degenerative processes were the most common changes (41 patients, 34.7%), first of all in the acromioclavicular joint (21 cases, 17.8%). Aseptic necrosis was observed in two patients. CONCLUSIONS: The miners are professionally exposed not only to hand-arm vibration, but also to increased physical stress. The symptoms on the upper limbs can develop as the result of both exposures.

Adult↗
PubMed1991

[The potentials for errors in the hygienic assessment of the general vibrations in tractors].

The data for the parameters of the general vibrations in tractors are comparatively scanty and contradictory. In the present work are analyzed the most frequently met omissions and errors in the measurement and evaluation of the general vibrations, as well as the factors, which can effect the intensity of the general vibrations; constructive and technological peculiarities, technical state, rate of machine amortization, construction, damping qualities, and regulation of the seat, motion velocity, relief, type of the performed agricultural activity. The necessity for taking under consideration these factors in measuring the general vibrations and the hygiene interpretation of the data, as well as precise report on the daily, weekly and general exposure, in view of defining the total vibration loading, is underlined.

Agriculture↗
PubMed1991

Vibration arthrometry in congenital dislocation of the hip.

Three hundred six neonates referred to a research clinic for vibration arthrometry were studied to determine whether the application of objective methods could enhance the accuracy of hip examinations. A total of 629 vibration episodes (hip "clicks" and "clunks") were detected using miniature accelerometers and recorded during testing for congenital dislocation of the hip. Five categories of congenital dislocations of the hip (CDH) were defined: normal (53 cases), safe click (201 cases), click associated with later CDH (16 cases), unstable (14 cases), and late CDH (22 cases). Follow-up examinations were performed over a four-year period. Detailed measurement of vibration signals was possible and resulted in the resolution of eight variables for each episode. Two variables, pulse area and peak frequency, were selected for their power to discriminate between the five clinical groups. The pulse area values were higher for the late and unstable groups. In addition, the vibrations were examined using Fourier analysis, and the safe click group demonstrated higher frequency components than any other group. Vibration arthrometry is proposed as a possible adjunct in screening for CDH, as it may pick up cases that would be missed by an average examiner and it could monitor clicks, thus avoiding nonessential splintage.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Effects of noise and vibration on farm workers.

A variety of significant health effects are associated with occupational exposures to noise and vibration, which are an integral part of many agricultural operations. Since vibrating surfaces represent one of the primary sources of noise, exposures to both types of physical stressors are commonly encountered. The effects of noise and vibration exposures may be exacerbated among farm workers because they tend to be more isolated than workers in other types of industry. As a consequence, access to health and safety information, medical care, and hazard control technology may be more restricted. Medical practitioners who serve the agricultural community must be aware of the consequences of exposures to noise and vibration. A primary duty involves conducting baseline and periodic examinations to catch diseases associated with such exposures at an early stage, when the condition is still reversible. In addition, the practitioner's role also includes prevention of disease through education of workers regarding the effects of noise and vibration and through helping specify procedures and strategies that will result in exposure reductions.

Agricultural Workers' Diseases↗
PubMed1990

[A method of determining the permissible time of working with vibration-generating hand-operated machines].

To limit the hazardous action of local vibration, a special nomogram was elaborated to determine, basing on newly established hygienic norms and regulations, the admissible duration of working with hand-operated vibrators. The normogram was based on the relation of vibrocontact duration to the vibration intensity, and was recommended to be applied to hand-operated vibrators with vibration intensity lower 10 cm/s (126dB).

Engineering↗
PubMed1990

Electromyographic reflexes evoked in human flexor carpi radialis by tendon vibration.

The rectified, electromyographic (EMG) reflexes evoked in the voluntarily contracting flexor carpi radialis (FCR) muscle by vibration of its tendon were studied in healthy human subjects. Responses comprised a prominent, transient, short-latency (SL, 20-25 ms) increase in EMG, attributed to Ia mono- and/or oligo-synaptic action, followed by a series of less pronounced troughs and peaks of activity. Evidence of continuing Ia mono- or oligo-synaptic action was indicated by (i) the presence of small subpeaks, at vibration frequency, superimposed upon the excitatory components and (ii) the occurrence of a separate reduction in EMG, of consistent latency (ca. 30 ms), after cessation of stimulation. Progressively shortening the train of vibration from 29 cycles (at 145 Hz) to a single cycle significantly reduced net, excitatory reflex activity. Gradually increasing the level (10-50% maximum) of pre-existing voluntary contraction on top of which reflexes were elicited, by moderately prolonged (29 cycles) trains of vibration, resulted in small increases, in absolute terms, in SL peaks and in later, excitatory EMG activity. Excitatory reflexes, when normalised for pre-stimulus EMG, however, declined in an approximately hyperbolic manner with increasing background activity over this range. Thus, effective "automatic gain compensation" does not operate for vibration reflexes in FCR.

Adult↗
PubMed1990

[Prognostication on the development of vibration disease in laborers using manual machines].

Prognosing of vibration disease (VD) is normally made both with regard to the number of the VD cases depending on the duration of work in vibration-hazardous professions, and with respect to its latent period. The results of prognosing depend to a vast extent on the methodological principles and criteria used. The data obtained from an epidemiological survey helped to determine quantitatively the interdependence between the vibration dosage and the VD latent period calculation on the average working day dosage basis. It was also shown that in case with marked high frequency and low frequency vibrations, as well as in combinations of vibration with other industrial factors, the calculated VD period can be shortened or prolonged) by 1-3 years. Further improvement of the VD prognosing techniques should be based on the evaluation of group and individual risk-factors criteria.

Humans↗