Maximum Sound Intensity Research Articles

Study on the design of control valve for U-shaped noise reduction cage and its fluid flow features and noise

In response to technical issues such as the ineffective noise reduction impact of balanced cage and single-seat control valves, the U-shaped noise reduction cage control valve is investigated and developed. In addition, its equal percentage flow properties and noise reduction impact are good, allowing it to effectively minimize the noise created by the change of fluid parameters of medium such as vapor, gas, and gas-liquid two-phase flow. The flow coefficient and flow properties were analyzed. The noise features of the medium air flow at small and large openings of 30% and 85% are simulated and analyzed, respectively. The pressure, velocity, and temperature of the inlet and outlet air, as well as the sound intensity maximum and sound power level maximum, are also analyzed with the opening curves. A small opening of 30% was selected, and the noise characteristics of cavitation generated by the medium water flow were simulated and analyzed. Together with the pressure and temperature change curves of the incoming water, the volume maxima and density minima of water are studied. The maximum sound intensity and sound power level of water are analyzed using the pressure and temperature curves of inlet water, as well as the cavitation coefficient and the degree of opening. The results of the trial for the pressure resistance of the valve body and the trial for the valve seat seal indicate that both the valve body strength and the valve seat seal meet the specifications. Comparing the noise trial results and simulation results reveals that the sound intensity and sound power level assessed by the trial and simulation are comparable, and the noise reduction impact of the control valve is positive.

The Noise Level Measurements of Children’s Sound Books

Purpose: It was intended to measure the sound intensity of children's sound books and to compare them with the standards of Korea and the International Standards Organization (ISO).Methods: The loudness of 15 children’s sound books was measured at a distance of 25 cm (child’s arm length), and 2.5 cm length of external auditory canal. Measurements taken three times with each book were performed, and the overall sound intensity of the sound books and the sound intensity of each button were measured and compared.Results: Compared with the Korean standard, all the buttons of all books exceeded the standard for the sound volume of the children’s book measured at a distance of 2.5 cm. When comparing the maximum sound intensity measured at a distance of 25 cm with 85 LAmax, a total of 168 buttons of these, 25 (14.88%) were recorded as exceeding the maximum loudness. According to the standards of the ISO, all buttons in all books were below the standard 85 LAeq.Conclusion: Several children’s books are loud enough to cause noise-induced hearing loss, especially when they are placed close to the ear. Strict standards for sound children’s books are required, and it is important to put a warning on the cover of the book. It is expected that the sound intensity of the children’s sound book presented in this study can be referenced when referring to the loudness during hearing rehabilitation in children.

STFT를 사용한 음성 신호 기반의 감정 분류 연구

The human voice has various characteristics, such as, loudness, pitch, speaking rate, etc. This research presents the classification method of human emotions using voice signals transformed using the short-time Fourier transform (STFT). The STFT can know the frequency component at a desired time point which can be verified using three criteria. Using the 1st criteria, that is, the frequency of the maximum sound intensity (MSI), the emotions can be classified into two groups normal/angry and happy. It is impossible to distinguish between the emotions using the 2<SUP>nd</SUP> criteria, which is, the dwell time of the MSI. Using the 3<SUP>rd</SUP> criteria, that is, the onset of the MSI, the two groups normal, and angry/happy are identified. Therefore, the 1<SUP>st</SUP> and 3<SUP>rd</SUP> criteria can be used to classify three emotions. These results can provide valuable insight for future research on the classification of human emotions.

Kentong Damping Sound Intensity Level Based on Kentongan Length Variations

This study aims to determine the attenuation of the sound produced by a Kentongan musical instrument based on variations in the length of the Kentongan. Data were collected in a quiet room by starting to measure the noise and atmosphere of the room. This study used Sound Meter Software with version 3.4.5 with a maximum sound intensity limit of ~ 90 dB, mobile as an intermediary. This study used Kentongan with a length of 1, 29 cm and a length of 2 that was 34.1 cm. Experiments were carried out 3 times with the first experiment without Kentongan, then Kentongan 1 and then Kentongan 2. The sound intensity produced by without Kentongan is an average of 60.08 dB, then with Kentongan 1 that is, with an average of 61.86 dB, and Kentongan 2 with an average of 56.68 dB. ©2019 JNSMR UIN Walisongo. All rights reserved.

Clinical and polysomnographic determinants of snoring

Snoring is considered one of the hallmarks of sleep-disordered breathing, but its determinants remain obscure in both obstructive sleep apnoea (apnoeic) and non-apnoeic snorers. We aimed to document positional dependency of snoring along with its association with clinical and polysomnographic variables. Seventy-seven apnoeic and 27 non-apnoeic snorers who complained for every-night loud snoring and slept in supine and lateral positions in all sleep stages during overnight polysomnography were included. Snoring (i.e. sound intensity > 40 dB) was quantified by measuring the mean and maximum sound intensity, and snoring frequency. In apnoeic and non-apnoeic snorers, mean snoring intensity and snoring frequency were higher in supine than in lateral positions irrespective of sleep stage, and were also usually higher in N3 in comparison to rapid eye movement and/or N2 sleep stage in any given position. Positional change in snoring intensity as expressed by the ratio of mean intensity in the supine to lateral positions was independently and positively correlated with body mass index, tonsils size and age in the total of patients. Snoring is more prominent in the supine position and in N3 sleep stage in apnoeic and non-apnoeic snorers. Snoring positional dependence is determined by body mass index, tonsils size and age.

Noise Radiation Characteristics of the Washing Machine Based on Sound Intensity Measurement

Based on the sound intensity measurement and analyzing, the noise radiated from the washing machine with horizontal axis was discussed to identify the noise source and find its propagation path. According to the principle of the sound intensity measurement, the measurement grids were arranged at the outside surfaces of the washer, and the distance was set to 20cm. The result showed that the noise source was near the right surface of washer’s motor installing. The maximum sound intensity values are mainly in frequency bands of 2 KHz and 4 KHz. Back surface of washer with sound power level 51 dB radiated the maximum sound intensity value 55.8 dB for 2 KHz and 56.0 dB for 4 KHz. There was also appeared the maximum sound intensity of low frequency 100 Hz in Right surface, which was caused by the vibration of motor transferring to the right surface shell. The results can provide technology support for the noise control of washing machine.

Vestibular Evoked Myogenic Potentials in Normal Mice and Phex Mice With Spontaneous Endolymphatic Hydrops

Vestibular evoked myogenic potentials (VEMPs) have been recorded from the neck musculature and the cervical spinal cord in humans and a limited number of laboratory animals in response to loud sound. However, the mouse VEMP has yet to be described. Evaluation of the sacculocollic pathway via VEMPs in mice can set the stage for future evaluations of mutant mice that now play an important role in research regarding human auditory and vestibular dysfunction. Sound-evoked potentials were recorded from the neck extensor muscles and the cervical spinal cord in normal adult mice and in circling Phex(Hyp-Duk/y) mice with known vestibular abnormalities, including endolymphatic hydrops (ELH). Biphasic potentials were recorded from all normal animals. The mean threshold of the VEMP response in normal adult mice was 60 dB normal hearing level with a mean peak latency of 6.25 +/- 0.46 and 7.95 +/- 0.42 milliseconds for p1 and n1 peaks, respectively. At the maximum sound intensity used (100 dB normal hearing level), 4 of 5 Phex mice did not exhibit VEMP responses, and 1 showed an elevated threshold, but normal response, with regard to peak latency and amplitude. The histologic findings in all of these Phex mice were consistent with distended membranous labyrinth, displaced Reissner membrane, ganglion cell loss, and ELH. This is the first report of VEMP recordings in mice and the first report of abnormal VEMPs in a mouse model with ELH. The characteristics of these potentials such as higher response threshold in comparison to auditory brainstem response, myogenic nature of the response, and latency correlation with the cervical recording (accessory nerve nucleus) were similar to those of VEMPs in humans, guinea pigs, cats, and rats, suggesting that the mouse may be used as an animal model in the study of VEMPs. The simplicity and reliability of these recordings make the VEMP a uniquely informative test for assessing vestibular function, and these results suggest that they may be informative in mice with various mutations. However, further investigation is necessary.

Evaluation of the Usefulness of Spectral Analysis of Inspiratory Lung Sounds Recorded with Phonopneumography in Patients with Interstitial Pneumonia

We investigated whether spectral analysis with fast Fourier transform (FFT) of inspiratory lung sounds is useful in the diagnosis and evaluation of the severity of interstitial pneumonia (IP). The study population included 10 healthy volunteers (healthy group) and 21 patients with IP (IP group). We generated inspiratory averaged linear intensities using FFT and determined frequency at maximum sound intensity (Fmax), and quartile frequencies (f25, f50, and f75), compared these values between the groups, generated receiver operating characteristic curves to compare the detectability of IP between the indices and auscultation in all cases, and tested for the correlation of these indices with pulmonary function tests and the fibrosis scores from high-resolution computed tomography images assessed by 3 observers. Both f50 and f75 were significantly higher in the IP group, but their ability to detect IP was inferior to that of auscultation. They had negative correlations with percent vital capacity and had positive correlations with the fibrosis scores calculated by the 3 different observers. These results were considered to reflect the presence of fine crackles and alterations in pulmonary sound-conduction characteristics caused by IP and indicate that spectral analysis of lung sounds is useful in the diagnosis and evaluation of the severity of IP, although future study is necessary to improve its utility.

Influence of Ribs on the Nonlinear Sound Field of Therapeutic Ultrasound

This article theoretically and experimentally studies the influence of ribs on the nonlinear sound field in ultrasound thermal therapy. A three-dimensional (3-D) numerical algorithm is developed to solve the Khokhlov-Zabolotaskaya-Kuznetsov equation in the frequency domain for description of the asymmetrical nonlinear ultrasound field. Two kinds of rib configurations are used to simulate the typical situations in the therapeutic treatment of liver tissues. Both numerical simulations and experimental measurements are made to evaluate the effect of the rib cage on the nonlinear ultrasound field. Results indicate that (1) when the ultrasound propagates through the space between the ribs, the position of the maximum amplitude of the fundamental component is shifted toward the transmitter surface up to 20 mm in some configuration; the maximum sound intensity can be either enhanced to 106% or decreased to about 20% compared with the value in the free field and the beam width in situ is affected by the sound diffraction; and (2) in the case of a rib positioned in the way of ultrasound propagation, the sound energy is significantly decreased and severe interference is observed. Satisfactory agreement between the theoretical prediction and measured results demonstrates the validity of the theoretical model and its solution. (E-mail: xzliu@nju.edu.cn)

A three-dimensional sound intensity measurement system for sound source identification and sound power determination by ln models

This paper describes a full vector intensity probe which advances the field of sound intensity and sound source direction estimation using six matched rotating and variable directional microphones. The probe has three pairs of microphones at an equal spacing of 30 mm that are set up in each of the x, y, and z directions and share the same observation point. The calibration method using the rotating microphone system is effective to correct position errors in the y- and z-axes microphone pairs. Sound intensity measurements using the variable directional microphone method can locate with accuracy a sound source, i.e., the structure parts radiating most acoustic energy. The system can find the maximum sound intensity level and beamwidth of the major lobe, and the peak sound intensity levels of the minor lobes. Therefore, a procedure for sound power determination based on minimum measurement data is theoretically and experimentally discussed. Consequently, it is possible to reconstruct only parts of the system emitting the most noise and measure efficiently the sound power level.

The influence of wood fiber direction, feed rate, and cutting width on sound intensity during routing

This study examines the possibility of using sound intensity to monitor the wood routing process at different machining conditions. Sound intensity is defined as the rate of flow of acoustic energy per unit area in a specified direction. For this study, specimens of Japanese beech (Fagus crenata Blume) were routed on a CNC machine tool equipped with an automatic feed. The effect of wood grain angle on the sound intensity energy generated and surface roughness produced was determined. Maximum sound intensity during routing was generated at an inclination of 135° to the grain. A linear relationship between sound intensity output and workpiece feed rate was recognized. Sound intensity and surface roughness are also strongly correlated, irrespective of feed rate. In contrast, sound intensity more than doubled with doubling of cutting width, whereas surface roughness did not increase. The results suggest that the measurement of sound intensity is a promising method for monitoring surface roughness and determining optimum feed rates.

A quality of parametric wave phase conjugation of ultrasound

The criterion, known from optics, of wave phase conjugation quality is accommodated for acoustical experiment. An incident focused sound beam at 5 MHz is propagated towards a supercritical magnetoelastic conjugator through an introduced random phase layer, and the conjugate beam propagates backwards through the layer to the source. 1D and 2D distributions of wave field are measured for the conjugate beam of finite amplitude using a membrane hydrophone. The maximum sound intensity of 640 W/cm 2 and acoustic power of 4 W are registered in the focal maximum of the conjugate wave. The quality of WPC is calculated from the ratio between the power in the central maximum and the total power of the conjugate beam. The method is applied to compare two operation modes of a supercritical parametric conjugator. It is shown that in the linear mode the conjugator provides higher quality than in the nonlinear (0.54 compared to 0.24).

Parchment-skin illusion: sound-biased touch

Our brains continuously bind information obtained through many sensory channels to form solid percepts of objects and events. Usually these pieces of information complement and confirm each other, thereby improving the reliability of our perception [1xStein, B and Meredith, M. See all References][1]. But incongruities between the sensory inputs may result in unexpected percepts due to intersensory interactions, as in the well-known audiovisual McGurk illusion [2xHearing lips and seeing voices. McGurk, H and MacDonald, J. Science. 1976; 264: 746–748See all References][2].Audiotactile interactions have remained largely unexplored [1xStein, B and Meredith, M. See all References][1], although Paul von Schiller [3xDie Rauhigkeit als intermodale Erscheinung. von Schiller, P. Z Psychol Bd. 1932; 127: 265–289See all References][3] noted in 1932 that sounds — noise bursts or tones repeated at regular intervals — may affect tactile perception of roughness. We describe here a novel audiotactile interaction, ‘parchment-skin illusion’, which demonstrates that sounds that are exactly synchronous with hand-rubbing may strongly modify the resulting tactile sensations.The subjects were seated with forearms supported on their thighs. A microphone close to the hands was recording the sounds produced when the subjects rubbed their palms together in a back-and-forth motion at 1–2 cycles per second. The sounds were played back to the subject through headphones. This audio feedback was either identical to the original sound or modified so that the high frequencies (above 2 kHz) were either dampened by or accentuated by 15 decibels (dB). In addition, the maximum sound intensity, which was adjusted to a comfortable listening level, was attenuated by either 20 or 40 dB, resulting in a randomized experiment of 3 ×3 block design, as shown in Table 1Table 1.Table 1 Tactile sensation of skin roughness. View Table in HTML Tactile sensation of relative skin roughness as a function of quality of the auditory feedback; mean ± SEMs of 11 subjects. The original estimates of skin roughness were given on a 0 (rough or moist) to 10 (smooth or dry) scale but as the individual ranges varied from 3.5 to 10, the values were normalized according to the range of each individual before averaging. The individual values were means of two repeated tests.During the pilot sessions several subjects spontaneously reported that the enhanced high-frequency feedback made the palmar skin feel drier, almost resembling parchment paper; this effect was found in 13 out of 17 healthy adults tested. Moisture on the palmar skin typically prevented the phenomenon.Eleven subjects (six males, five females; age range 25–49 years) who reported the phenomenon in a consistent manner were asked to quantify the tactile sensations on their palms during varying audio feedback conditions on a scale of 0 to 10, referring to a range rough/moist–smooth/dry, respectively. The audio feedback had a very clear effect on the tactile sensation as is evident from Table 1Table 1.When either the proportion of the high frequencies or the average sound level of the auditory feedback increased, the skin started to feel more paper-like, that is, the perceived roughness/moisture of the palmar skin decreased and the smoothness/dryness increased. The effects of both the high-frequency content and the average intensity of the feedback were statistically highly significant (by analysis of variance). Tactile sensitivity — tested with von Frey hairs in two subjects while they performed the task with audio feedback — was not modified during the illusion, as compared with the no-feedback condition with the hands at rest.An additional experiment with two experienced subjects showed that a delay of the audio feedback by more than 100 milliseconds clearly diminished the illusion. Efficient binding of multisensory inputs evidently requires accurate temporal coincidence, or a temporal window for multisensory integration (as discussed in [4xRepresentation and integration of multiple sensory inputs in primate superior colliculus. Wallace, MT, Wilkinson, LK, and Stein, BE. J Neurophysiol. 1996; 76: 1246–1266PubMedSee all References][4]), which naturally happens when the subjects hear the sounds produced by their own hand movements.We hypothesize that the parchment-skin illusion reflects an omnipresent intersensory integration phenomenon, which helps the subject to make accurate tactile decisions about the roughness and stiffness of different textures they manipulate.

Thermal boundary layer effects in an annular acoustic Stirling engine

A stability and transport analysis is performed for a simplified model of a strongly coupled thermoacoustic prime mover stack in an annular resonator. The result demonstrates that, even in the limit that other flow impedances of the resonator and stack can be ignored, there is a thermal impedance mismatch created in the boundary region at the ends of the stack. This can cause the gain predicted for the wave traversing the interior of the stack to differ significantly from the gain that drives sound in the resonator. The analysis is used to derive scaling relations between the heat and mass transport around the annulus, and to show how different scaling regimes relate to the maximum sound intensity that the stack can induce in the absence of other losses.

Spatial processing within the mustache bat echolocation system: possible mechanisms for optimization.

1. The directionality of an echolocation system is determined by the acoustic properties of both the emitter and receiver, i.e., by the radiation pattern of the emitted pulse and the directionally of the external ears. We measured the directionality of the echolocation system of the greater mustache bat (Pteronotus parnellii) at the 30 kHz, 60 kHz and 90 kHz harmonics of its echolocation pulse by summing, at points throughout the frontal sound field, the echo attenuation due to the spread of pulse energy and the attenuation due to the spread of pulse energy and the attenuation due to the directionality of its external ears. The pulse radiation pattern at the 3 harmonics was measured by comparing the output of a microphone moved throughout the frontal sound field against a second reference microphone at the center of the field. External ear directionality at the 3. harmonics was measured by presenting free-field sounds throughout the frontal sound field, and recording the intensity thresholds of cochlear microphonic potentials, and the intensity thresholds of monaural neurons in the inferior colliculus tuned to one of the 3 harmonics. 2. When compared with ear directionality, the echolocation system was found to be more directional for the center of the sound field in several respects. At all harmonics, attenuation of sounds originating in the peripheral part of the field was increased by 10 to 13 dB. Areas of maximum sound intensity contracted toward the center of the field. Also, the isointensity contours of the echolocation system were more radially symmetrical about the center of the field. 3. At 60 kHz, sound intensity along the azimuth within the echolocation system was nearly constant 26 degrees to either side of the center of the field. This suggests that the radiation pattern of the echolocation pulse and the directionality of the external ears complement one another to produce an acoustic environment at the center of the sound field in which stimulus intensity is stabilized to allow more effective analysis of various aspects of the echolocation target. In particular, we suggest that this intensity stabilization may allow the bat to more effectively resolve the interaural intensity differences it uses to localize prey. 4. Predictions of the azimuthal spatial tuning of binaurally sensitive neurons in the inferior colliculus within the echolocation system were compared with their spatial tuning when only ear directionality is considered.(ABSTRACT TRUNCATED AT 400 WORDS)

EXPLORING AIRBORNE SOUND IN A NONVACUUM FREEZE‐DRYING PROCESS

SUMMARY– A study was made to determine if sound energy could be used to enhance freeze‐drying rates of foods and to analyze the kinetics in such a system. A prototype pilot freeze‐dryer with airborne sound was designed and built to freeze‐dry liquid foods, e.g., tea and coffee extracts. The sound source was a stem‐jet whistle producing 10.8–12.2 kcps with a maximum sound intensity level of 149 db. Desiccated compressed air at 70° to 90°F served as the driving force of the whistle as well as the carrier of the sublimed moisture. Experimental results showed this to be a feasible process. Sample temperature, inlet air pressure, the freeze‐dryer tube size, and the sound source, all had significant effects on the freeze‐drying rates. Freeze‐drying rates were 11–100% higher in the stem‐jet whistle runs than in the dummy whistle runs; 7% of this improvement was attributed to the thermal effect on the air resulting from friction and adiabatic compression. The remaining increase was due to the sound pressure energy, the increase in heat and mass transfer coefficients, and the “reduced‐pressure” effect in the sweeping air stream during the rarefaction cycle of the sonic vibration. The flaking action of the sound waves on near‐dried tea and coffee was considered a processing advantage because of the ease in product recovery and because a new surface was continuously being exposed for sublimation.

The Effect of Sound on Laminar Propane-Air Flames

The application of sound of known intensity and a frequency of 12.7 kc to a laminar propane-air flame is found to produce a shift in the stability limits of the flame. The sound alters the flashback limit so that the flame becomes more stable and the blowoff limit so that the flame becomes less stable. It is shown that the normal burning velocity is not changed with the application of sound and that the flow-velocity profile in the tube is likewise unchanged. From the Lewis and von Elbe theory of flame stabilization it is then concluded that the “penetration distance” must be increased. The “penetration distances” are calculated from the flow-velocity distribution and the normal burning velocity and, near stoichiometric, are found to increase about 20 percent at the maximum sound intensity of 10 milliwatts/cm2. Sound at a frequency of 18.3 kc is found to affect the blow-off limit in a similar manner as the lower frequency but no appreciable effect is noted on the flashback limit. It is concluded that these results in combination with further experimental studies should yield useful information about the nature of the “penetration distance” and flame holding in general, but that sound at these low frequencies does not offer a useful tool for studying flame propagation. It is recommended that the effects of sound on practical burners be given careful study because the results presented indicate that the maximum quantity of energy that can be released in a given burner volume may be limited by the sound level in the combustion chamber.

A Simple Method of Finding the Sound Absorbing Power of a Building Material

An accurate method of comparing the absorbing powers of building materials is described. As in Taylor's method, a Rayleigh disk is used to examine the standing waves inside a tube, one end of which is closed by the test material. The main feature of the method is the comparison of the values of the maximum sound intensity in the standing waves when the end of the tube is closed first by a hard material and then by the material under test. The results are accurately reproducible.Absorption coefficient at pitch 295 of various building materials.---The following values of the absorption coefficient were obtained:---commercial Celotex, $\frac{7}{{16}^{\ensuremath{'}\ensuremath{'}}}$, not perforated, 0.17; acoustical Celotex, $\frac{7}{{8}^{\ensuremath{'}\ensuremath{'}}}$, perforated side exposed, 0.34; J. M. Asbestos Akoustikos felt, $\frac{1}{{2}^{\ensuremath{'}\ensuremath{'}}}$ thick, one layer, 0.15; two layers, 0.43; J. M. Akoustikos felt, 1\ensuremath{''} thick (older type), 0.13; Akoustolith, 1\ensuremath{''} thick, tile, 0.15; Rumford tile, 1\ensuremath{''} thick, 0.22.