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PubMed1982

Sound levels inside incubators and oxygen hoods used with nebulizers and humidifiers.

Degree of hearing loss in the infant is related to high-intensity or high-frequency sound (noise). We measured sound levels of 6 models of pneumatic nebulizers and 8 models of humidifiers at various flowrates, FIO2 settings, and water levels, when they were attached to incubators and oxygen hoods; we also evaluated sound levels from 2 models of ultrasonic nebulizers at various output settings. Among the pneumatic nebulizers, the recommended 58-dbA maximum sound level was exceeded by the Aquapak 621, Ohio Deluxe, and Puritan All-Purpose devices. The Bard Parker, Foregger, and Inspiron pneumatic nebulizers' sound levels were 58 dbA or below except during the dry water-level condition. Among the humidifiers, all produced sound levels below the recommended 58-dbA maximum except the Travenol humidifier; the Bennett Cascade, Conchapak, Foregger, and Hudson humidifiers produced mean sound levels in the 43.0- to 43.5-dbA range. Sound levels increased under all conditions when the devices were used with oxygen hoods. The ultrasonic nebulizers produced low sound levels, but the high-frequency ultrasound they also produce may be undesirable for infants; this question requires further investigation.

Equipment Design↗
PubMed1990

[Three orthodontic cases with temporomandibular joint sounds].

Three orthodontically treated cases with sounds of the temporomandibular joint are presented. Case 1: Eight months after [formula: see text] extraction, bilateral TMJ sounds were noticed. The patient had a history of pre-orthodontic TMJ sounds and locking. A disc recapturing splint was therefore set on the upper arch, then changed into a stabilization splint for 5 months. The TMJ sounds faded away and the active treatment was completed. Case 2: The patient had [formula: see text] missing teeth, severe deep bite, upper and lower spaced arches. She also had mild facial deformity and bilateral TMJ sounds. TMJ arthroscopy showed right side "Anterior disk displacement without reduction" and left side "Anterior disk displacement with reduction". Maxillary spaces were closed following standard splint therapy. Right side TMJ sound diminished considerably while left side sound faded away completely. Finally, prosthodontic treatment was performed. Case 3: The patient had mandibular right side shifting, upper and lower crowding and a right side TMJ sound. Initially, maxillary lateral expansion was performed using a Quad-helix appliance. Simultaneously a positioner-type splint was used on the lower arch for avoiding any occlusal interference. TMJ sound faded away and a standard [formula: see text] extraction treatment was completed for crowding correction and better occlusion.

Female↗
PubMed1993

Sound spectral analysis of prosthetic valvular clicks for diagnosis of thrombosed Björk-Shiley tilting standard disc valve prostheses.

To evaluate clinical usefulness of sound spectral analysis in the early detection of prosthetic thrombosis, we analyzed specific patterns of thrombus formation in Björk-Shiley tilting standard disc prostheses in relation to the sound spectral analysis of their click sounds. Among a total of 365 Björk-Shiley tilting standard disc prostheses, nine became thrombotic. These consisted of seven prostheses in the mitral position and two in the aortic position, and the affected valves were replaced in all cases. The sound spectral analysis system includes a wide-frequency microphone and a sound spectral analyzer. To quantify the amplitude of the metallic clicks that are specific to the prosthetic valve sounds, we used a normalized maximal frequency as a diagnostic parameter for valve thrombosis. Thrombus formation was localized at the minor strut in two cases, and these demonstrated abnormally low normalized maximal frequency values only on opening clicks. In four cases thrombus formations were noted at both minor and major struts, and these showed abnormally low normalized maximal frequency values on both opening and closing clicks. In two cases with pannus formation, no abnormalities were found by sound spectral analysis. In one case, which had demonstrated abnormally decreased normalized maximal frequency values of both opening and closing clicks, the normalized maximal frequency values were normalized after thrombolytic therapy, suggesting resolved thrombosis. Reoperation, which was performed for concomitant complication of perivalvular leak, revealed no noticeable thrombus formation. The thrombi were seen on the minor strut during surgical procedures in all cases in which valve thrombosis was indicated by the sound spectral analysis. Therefore, the minor strut is considered to be the prevalent area of thrombus formation, and diagnosis could be made after observation of abnormally low normalized maximal frequency on opening clicks. We found the sound spectral analysis to be an extremely useful diagnostic tool for early detection of thrombosis in the Björk-Shiley tilting standard disc prostheses, especially because the opening clicks of the tilting disc valve were too low in amplitude for auscultation to detect the existence of mild abnormality.

Adolescent↗
PubMed1996

Some Applications of the Sound Intensity Technique to Noise Control in the Workplace.

Over a decade has elapsed since commercial sound intensity measurement systems became available. A literature search has shown that the sound intensity technique has found increasing applications in recent years. In this article, the principle and errors of the sound intensity technique are briefly described. Four case studies are given to illustrate how the sound intensity technique can be applied to determine sound power under both laboratory and field conditions, to identify noise source and to measure sound transmission loss o f composite partitions "in situ." It has been shown that, provided the limitations of the sound intensity technique are understood, results obtained by the sound intensity technique enable effective noise control to be implemented in the workplace.

identification noise control↗
PubMed2004

Effects of sounds generated by a dental turbine and a stream on regional cerebral blood flow and cardiovascular responses.

Effects of sound generated by a dental turbine and a small stream (murmur) and the effects of no sound (null, control) on heart rate, systolic and diastolic blood pressure, and hemodynamic changes (oxygenated, deoxygenated, and total hemoglobin concentrations) in the frontal cortex were measured in 18 young volunteers. Questionnaires completed by the volunteers were also evaluated. Near-infrared spectroscopy and the Finapres technique were employed to measure hemodynamic and vascular responses, respectively. The subjects assessed the murmur, null, and turbine sounds as "pleasant," "natural," and "unpleasant," respectively. Blood pressures changed in response to the murmur, null, and turbine sound stimuli as expected: lower than the control level, unchanged, and higher than the control level, respectively. Mean blood pressure values tended to increase gradually over the recording time even during the null sound stimulation, possibly because of the recording environment. Oxygenated hemoglobin concentrations decreased drastically in response to the dental turbine sound, while deoxygenated hemoglobin concentrations remained unchanged and thus total hemoglobin concentrations decreased (due to the decreased oxygenated hemoglobin concentrations). Hemodynamic responses to the murmuring sound and the null sound were slight or unchanged, respectively. Surprisingly, heart rate measurements remained fairly stable in response to the stimulatory noises. In conclusion, we demonstrate here that sound generated by a dental turbine may affect cerebral blood flow and metabolism as well as autonomic responses.

Acoustic Stimulation↗
PubMed1995

Conceptual relationships between spoken words and environmental sounds: event-related brain potential measures.

Identifiable nonspeech sounds were paired with spoken words. In Experiment 1, words preceded by related sounds yielded faster lexical decision times than those preceded by unrelated sounds. In Experiment 2, subjects were presented with sound/word and word/sound pairs while event-related potentials were recorded. Words preceded by related sounds elicited smaller N400 components than those preceded by unrelated sounds; this N400 context effect was slightly larger at electrode sites over the right hemisphere. A context effect similar in latency and morphology was observed for sounds-a smaller negative wave for related than unrelated sounds. The context effect for sounds was significantly larger at left than right recording sites, suggesting differential hemispheric involvement in the processing of word meanings than the "meanings" of environmental sounds.

Adult↗
PubMed2005

Learning of letter names and sounds and their contribution to word recognition.

This study investigated knowledge of letter names and letter sounds, their learning, and their contributions to word recognition. Of 123 preschoolers examined on letter knowledge, 65 underwent training on both letter names and letter sounds in a counterbalanced order. Prior to training, children were more advanced in associating letters with their names than with their sounds and could provide the sound of a letter only if they could name it. However, children learned more easily to associate letters with sounds than with names. Training just on names improved performance on sounds, but the sounds produced were extended (CV) rather than phonemic. Learning sounds facilitated later learning of the same letters' names, but not vice versa. Training either on names or on sounds improved word recognition and explanation of printed words. Results are discussed with reference to cognitive and societal factors affecting letter knowledge acquisition, features of the Hebrew alphabet and orthography, and educational implications.

Child, Preschool↗
PubMed2004

Sound sequence discrimination learning is dependent on cholinergic inputs to the rat auditory cortex.

In rat auditory cortex (AC) slices, synaptic potentiation following heterosynaptic stimulation is affected by the stimulus sequence used for induction. It was hypothesized that this sequence-dependent plasticity might be partly involved in the cellular mechanisms underlying sound sequence discrimination. Sequence dependence is abolished by muscarinic receptor antagonists. Therefore, dependence of sound sequence discrimination learning on cholinergic inputs to the rat AC was investigated. Rats were trained to discriminate the sequences of two sound components and a licking behavior in response to one of two possible sequences was rewarded with water. Atropine, a muscarinic receptor antagonist, attenuated sound sequence discrimination learning. The acquired sound sequence discrimination was not affected by atropine. Injections of the cholinergic immunotoxin 192IgG-saporin into the AC suppressed sound sequence discrimination learning, while discrimination between the two sound components was not affected. An inhibitor of M-current, linopirdine, restores the sequence dependence of synaptic potentiation in the AC slices suppressed by atropine. In this study, sound sequence discrimination learning attenuated by 192IgG-saporin was also restored by linopirdine. These similarities between sequence dependent plasticity in the AC slices and sound sequence discrimination learning support the hypothesis that the former is involved in the cellular mechanisms underlying the latter.

Acetylcholine↗
PubMed2005

Superior temporal and inferior frontal cortices are activated by infrequent sound duration decrements: an fMRI study.

Functional magnetic resonance imaging (fMRI) was used to examine the processing of infrequent changes occurring in an unattended sound sequence. In event-related brain potentials (ERPs), such sound changes typically elicit several responses, including an enhanced N1, the mismatch negativity (MMN), and the P3a. In the present study, subjects were presented with a repeating sound of 75 ms in duration, which was occasionally replaced, in separate blocks, by a 15-ms, 25-ms, or 35-ms sound (large, medium, and small change, respectively). In the baseline block, only the frequent 75-ms sound was presented. During the scanning, the subjects were instructed to ignore the sounds while watching a silent wildlife documentary. We assumed that in this condition, the MMN mechanism would contribute more to the observed activation than the other change-related processes. We expected sound changes to elicit fMRI activation bilaterally in the supratemporal cortices, where the electric MMN is mainly generated, and that the magnitude of this activation would increase with the magnitude of sound duration change. Unexpectedly, however, we found that only blocks with medium duration changes (25 ms) showed significant activation in the supratemporal cortex. In addition, as reported in some previous EEG and fMRI studies, contrasts between different levels of sound duration change revealed additional activation in the inferior frontal cortex bilaterally. This activation tended to be greater for the small and medium changes than for the large ones.

Acoustic Stimulation↗
PubMed2005

Schlieren photography to study sound interaction with highly absorbing materials.

Strong absorption of sound is often caused by the conversion of sound energy into heat. When this happens, it is not possible to study the interaction of sound with the absorbing material by means of reflected sound characteristics, because there is no reflected sound. Detecting for example the distance that sound travels in a strongly absorbing material, can be done by heat detection systems. However, the presence of temperature detectors in such materials interferes with the sound field and is therefore not really suitable. Infrared measurements are a possible option. Another option is the use of Schlieren photography for simultaneous visualization of sound and heat. This technique is briefly outlined with a 3 MHz sound beam incident on a highly absorbing sponge.

Journal Article↗
PubMed2004

[Sequential sound therapy in tinnitus].

The sequential sound therapy is a treatment for tinnitus with white noise that has some own characteristics. We describe the methodology, as well as their differences and similarities with the Tinnitus Retraining Therapy. The sequential sound therapy has been carried out to seventeen patients assisted during the year 2002. 26 generators of sound were adapted, of them, 22 had incorporated an earphone. The results of the sequential sound therapy were compared with those of the Tinnitus Retraining Therapy in 15 patients assisted during 2000 and 2001. The percentage of satisfactory results obtained with sequential sound therapy has been a 100%, while the therapy with sounds of the Tinnitus Retraining Therapy obtained a 33%. With the sequential sound therapy 6 patients had no further tinnitus. With the sequential sound therapy no patients has abandoned the treatment. With the treatment with sounds of the Tinnitus Retraining Therapy of the patients did give up the therapy 53%.

Acoustic Stimulation↗
PubMed2002

The effect of sound duration on rate-amplitude functions of inferior collicular neurons in the big brown bat, Eptesicus fuscus.

During echolocation, the amplitude and duration of echo pulses of the big brown bat, Eptesicus fuscus, covary throughout the entire course of hunting. The purpose of this study was to examine if variation in sound duration might affect the amplitude selectivity of inferior collicular (IC) neurons of this bat species under free-field stimulation conditions. A family of rate-amplitude functions of each IC neuron was obtained with different sound durations. The effect of sound duration on the neuron's amplitude selectivity was then studied by examining the type, best amplitude, dynamic range and slope of each rate-amplitude function. The rate-amplitude functions of 83 IC neurons determined with different sound durations were either monotonic, saturated or non-monotonic. Neurons with monotonic rate-amplitude functions had the highest best amplitude, largest dynamic range but smallest slope. Neurons with non-monotonic rate-amplitude functions had the lowest best amplitude, smallest dynamic range but largest slope. The best amplitude, dynamic range and slope of neurons with saturated rate-amplitude functions were intermediate between these two types. Rate-amplitude functions of one group (47, 57%) of IC neurons changed from one type to another with sound duration and one-third of these neurons were tuned to sound duration. As a result, the best amplitude, dynamic range, and slope also varied with sound duration. However, rate-amplitude functions of the other group (36, 43%) of IC neurons were hardly affected by sound duration and two-thirds of these neurons were tuned to sound duration. Biological relevance of these findings in relation to bat echolocation is discussed.

Acoustic Stimulation↗
PubMed1999

Acquired resistance to acoustic trauma by sound conditioning is primarily mediated by changes restricted to the cochlea, not by systemic responses.

Hearing loss caused by intense sound exposure can be significantly reduced by pre-exposing subjects to moderate-level acoustic stimuli. This phenomenon occurs in a variety of mammals. We investigated whether sound conditioning provides acquired resistance to acoustic trauma through local mechanisms selectively in the conditioned ears or if systemic mechanisms are involved that would yield contralateral protection in unconditioned ears. Guinea pigs (group I) in which one external ear canal was occluded were exposed to conditioning sound (2-20 kHz, 85 dB SPL, 5 h/day, 10 days). After removing the occlusion, the animals were then subjected bilaterally to intense noise (2-20 kHz, 110 dB SPL, 5 h) 5 days after the last conditioning exposure. Animals without ear canal occlusion were also exposed to the intense sound without conditioning (group II) or following the same conditioning exposure (group III). Intense sound exposure caused significantly greater permanent ABR threshold shifts at all frequencies tested (4, 8, 12, 16 and 20 kHz) in group II than in group III. In group I, the occluded ears showed significantly greater threshold shifts at all frequencies compared to the unoccluded ears. The threshold shifts in the occluded ears in group I were identical to those observed in group II; and the shifts in unoccluded ears in group I were identical to those in group III. Protective effects provided by sound conditioning were almost the same in group III and in the unoccluded ears in group I. The extent of hair cell damage supported the physiological findings. These results indicate that acquired resistance to acoustic trauma provided by sound conditioning is restricted to the cochlea exposed to conditioning sound, suggesting that conditioning protection is mediated primarily by the changes that occur locally within the conditioned cochlea. This animal model, with unilateral external ear canal occlusion during sound conditioning, is useful for studies of the mechanisms of conditioning protection.

Acoustic Stimulation↗
PubMed1999

Ambient sound levels in a state psychiatric hospital.

High environmental and psychosocial stress contribute to the onset and relapse of major psychiatric disorders. High sound levels in general hospitals are common and may be indirectly associated with negative physical effects because of increased physiological stress on the body. Excessive sound also interferes with cognitive functioning, especially affecting prefrontal cortical processes, but no information about sound levels in psychiatric hospitals was available. This study critically examines literature on sound stress and reports findings from an exploratory study of sound levels in a tertiary care psychiatric hospital. An overall mean sound level of 75.68 dB was found, with peak sound levels as high as 85 to 90 dB, in the range that causes hearing loss. These levels, higher than sound levels on medical, surgical, and intensive care units, suggest the need for more attention to the effect that environmental sound has on the behavior of patients hospitalized with acute psychiatric symptoms.

Adolescent↗
PubMed2003

Early postnatal sound exposure induces lasting neuronal changes in the inferior colliculus of senescence accelerated mice (SAMP8): a morphometric study on GABAergic neurons and NMDA expression.

Senescence-acceleration-prone mice (SAMP8) provide a model to study the influence of early postnatal sound exposure upon the aging auditory midbrain. SAMP8 were exposed to a 9-kHz monotone of either 53- or 65-dB sound pressure level during the first 30 postnatal days, the neurons in the auditory midbrain responding selectively to 9 kHz were localized by c-fos immunohistochemistry and the following parameters were compared to control SAMP8 not exposed to sound: mortality after sound exposure, dendritic spine density, and quantitative neurochemical alterations in this 9-kHz isofrequency lamina. For morphometric analysis, animals were examined at 1, 4, and 8 months of age. Serial sections of the inferior colliculus were Golgi impregnated or stained immunohistochemically for the expression of epsilon1 subunit of NMDA receptor or GABA. Mortality after exposure to 53 dB was the same as in controls, but was markedly increased from 7 months of age onward after postnatal exposure to 65 dB. No gross morphological alterations were observed in the auditory midbrain after sound exposure. However, sound exposure to 53 or 65 dB significantly reduced dendritic spine density by 11% at 4 months or by 11-17% both at 1 and 4 months of age, respectively. The effect of sound exposure upon neurons expressing the NMDAepsilon1 subunit was dose-dependent. Increasing with age until 4 months in control mice and remaining essentially stable thereafter, the percentage of NMDAepsilon1-immunoreactive neurons was significantly elevated by 40-66% in 1- and 8-month-old SAMP8 exposed to 53 dB, whereas no significant effect of 65 dB was apparent. The proportion of GABAergic cells declined with age in controls. It was significantly decreased at 1 month after 53 and 65 dB sound exposure. In contrast, it was elevated at later stages, being significantly increased at 4 months after exposure to 53 dB and at 8 months after exposure to 65 dB. The total cell number in the 9-kHz isofrequency lamina of SAMP8 decreased with age, but was not affected by exposure to either 53 or 65 dB. The present results indicate that early postnatal exposure to a monotone of mild intensity has long-term effects upon the aging auditory brain stem. Some of the changes induced by sound exposure, e.g., decline in spine density, are interpreted as accelerations of the normal aging process, whereas other effects, e.g., increased NMDAepsilon1 expression after 53 dB and elevated GABA expression after both 53 and 65 dB, are not merely explicable by accelerated aging.

Acoustic Stimulation↗
PubMed2004

Representation of sound categories in auditory cortical maps.

Functional magnetic resonance imaging (fMRI) was used to investigate the representation of sound categories in human auditory cortex. Experiment 1 investigated the representation of prototypical (good) and nonprototypical (bad) examples of a vowel sound. Listening to prototypical examples of a vowel resulted in less auditory cortical activation than did listening to nonprototypical examples. Experiments 2 and 3 investigated the effects of categorization training and discrimination training with novel nonspeech sounds on auditory cortical representations. The 2 training tasks were shown to have opposite effects on the auditory cortical representation of sounds experienced during training: Discrimination training led to an increase in the amount of activation caused by the training stimuli, whereas categorization training led to decreased activation. These results indicate that the brain efficiently shifts neural resources away from regions of acoustic space where discrimination between sounds is not behaviorally important (e.g., near the center of a sound category) and toward regions where accurate discrimination is needed. The results also provide a straightforward neural account of learned aspects of perceptual distortion near sound categories: Sounds from the center of a category are more difficult to discriminate from each other than sounds near category boundaries because they are represented by fewer cells in the auditory cortical areas.

Acoustic Stimulation↗
PubMed2000

Shrinkage of perceived tonal duration produced by extra sounds: effects of spectral density, temporal position, and transition direction.

To investigate the mental mechanism that estimates the duration of sounds, the subjective duration of a tone was measured. In the first experiment a portion of the target sound was replaced with another sound. In the second and third experiments another sound either started or ended in the middle of the target sound. Ten or eleven undergraduates participated as listeners in each of the experiments. In the first experiment, effects of spectral spacing and those of temporal position of the replacing sound were tested. Compared with the intact case, the subjective duration of the replaced target shrunk, and the degree of shrinkage increased as the spectral spacing became wider. The temporal position of the replacing sound did not affect the degree of shrinkage. In the second experiment, effects produced by the start (ON) of the concurrent sound and those by the end (OFF) were compared. The ON case was more effective than the OFF case. In the third experiment, effects of the rise time and fall time of the concurrent sound were tested. A long rise and fall time reduced the difference between the ON and OFF cases. These results are discussed from two viewpoints, one assuming an interaction between the time markers, the other assuming continuous gate control in a neural-counting model for duration.

Acoustic Stimulation↗
PubMed2004

Cortical differentiation of speech and nonspeech sounds at 100 ms: implications for dyslexia.

Neurophysiological measures indicate cortical sensitivity to speech sounds by 150 ms after stimulus onset. In this time window dyslexic subjects start to show abnormal cortical processing. We investigated whether phonetic analysis is reflected in the robust auditory cortical activation at approximately 100 ms (N100m), and whether dyslexic subjects show abnormal N100m responses to speech or nonspeech sounds. We used magnetoencephalography to record auditory responses of 10 normally reading and 10 dyslexic adults. The speech stimuli were synthetic Finnish speech sounds (/a/, /u/, /pa/, /ka/). The nonspeech stimuli were complex nonspeech sounds and simple sine wave tones, composed of the F1+F2+F3 and F2 formant frequencies of the speech sounds, respectively. All sounds evoked a prominent N100m response in the bilateral auditory cortices. The N100m activation was stronger to speech than nonspeech sounds in the left but not in the right auditory cortex, in both subject groups. The leftward shift of hemispheric balance for speech sounds is likely to reflect analysis at the phonetic level. In dyslexic subjects the overall interhemispheric amplitude balance and timing were altered for all sound types alike. Dyslexic individuals thus seem to have an unusual cortical organization of general auditory processing in the time window of speech-sensitive analysis.

Acoustic Stimulation↗