Variation Of Sound Pressure Level Research Articles

Dynamic changes of vocal tract dimensions with sound pressure level during messa di vocea).

The messa di voce (MdV), which consists of a continuous crescendo and subsequent decrescendo on one pitch is one of the more difficult exercises of the technical repertoire of Western classical singing. With rising lung pressure, regulatory adjustments both on the level of the glottis and the vocal tract are required to keep the pitch stable. The dynamic changes of vocal tract dimensions with the bidirectional variation of sound pressure level (SPL) during MdV were analyzed by two-dimensional real-time magnetic resonance imaging (25 frames/s) and synchronous audio recordings in 12 professional singer subjects. Close associations in the respective articulatory kinetics were found between SPL and lip opening, jaw opening, pharynx width, uvula elevation, and vertical larynx position. However, changes in vocal tract dimensions during plateaus of SPL suggest that perceived loudness could have been varied beyond the dimension of SPL. Further multimodal investigation, including the analysis of sound spectra, is needed for a better understanding of the role of vocal tract resonances in the control of vocal loudness in human phonation.

Experimental Study of Storing Electrical Energy Generated by an Acoustic Energy Harvester Into a Supercapacitor

<p class="Abstract">Acoustic energy harvester is a device used to convert environmental noise into electrical energy. Many researches on acoustic energy harvesting have been carried out, but most of them have not yet reached the stage of storing the electrical energy produced. This paper presents an experimental study of storing electrical energy generated by an acoustic energy harvester into a supercapacitor. The acoustic energy harvester in this study used a 4-inch woofer loudspeaker as a noise converter into electricity, equipped with a straight cylindrical resonator, a cylindrical housing, and an electric current rectifier unit. The supercapacitor used has a specification of 100F/2.7V. Experiments were carried out by using several variations of the sound frequency with three variations of sound pressure level (SPL) namely 90 dB, 95 dB, and 100 dB, and by measuring the supercapacitor voltage in a charging time of 60 minutes. It was found that the supercapacitor voltage reached 368 mV which was obtained from noise sound with an SPL of 100 dB and a frequency of 54 Hz which gave an initial charging electric current of about 12 mA. In the last five minutes of charging, the increase in supercapacitor voltage was still linear with time at a rate of about 5.2 mV/min. Therefore, the supercapacitor voltage can still significantly increase if the charging continues.</p>

The Normative Study of Acoustic and Aerodynamic Characteristics of Voice among Healthy Adult Turkish Speaker Population.

Phonatory Aerodynamic System (PAS Model 6600) is an evaluation instrument that assesses the effectiveness of surgical interventions, treatments, and therapy for voice disorders. It can be used for the assessment of voice disorders by supporting other perceptual and instrumental methods. It is important to establish normative data, because the use of appropriate norms is necessary for diagnostic and descriptive accuracy. Therefore, this study is aimed primarily at establishing adult normative databases for phonatory aerodynamic measures obtained with the KayPENTAX PAS Model 6600 among healthy adult Turkish speakers and then examining the effect of age, gender, and age-gender interaction variables on these measures. The contribution of the study is considered so important since it will generate normative data for all measurements—except the mean pitch—by the five protocols of PAS for the first time. Two hundred and six healthy Turkish speakers with normal voice (106 women and 100 men) were included in the study and stratified into three age groups. Forty-five phonatory aerodynamic measures across five PAS protocols (vital capacity, maximum sustained phonation, comfortable sustained phonation, variation in sound pressure level, and voicing efficiency) were collected. Age, gender, and age-gender interaction variables were analyzed for 45 PAS parameters. Significant gender and age effect was found for 30 and 19 variables, respectively. Gender-age interaction together was observed for only 6 parameters. Significant differences were not found for the remaining 10 parameters. Significant age and gender effects were observed for 35 phonatory and aerodynamic measures which are essential part of the objective clinical assessment of voice. Consequently, normative data used as reference in voice assessment should be generated according to age and gender differences.

Diffuseness Quantification in a Reverberation Chamber and Its Variation with Fine-Resolution Measurements

Insufficient diffuseness is the major cause of the poor repeatability and reproducibility of building acoustical measurements in a reverberation chamber. Inaccurate results were reported for the prevailing methods in ISO and ASTM standards. Many previous studies, thus, have proposed new methods to quantify the diffuseness of a reverberation chamber more accurately, but there is no general agreement among researchers on the most reliable method. The number of measurement samples required for these diffuseness metrics is also unclear, even though it significantly impacts the robustness of the methods. This study, therefore, aims to compare the performance of the two widely used diffuseness metrics (spatial variation of sound pressure levels and the relative standard deviation of decay rates) in the standards and the recently introduced metric (degree of time series fluctuation). The measurements were carried out with fine resolution microphone positions and varied configurations of acoustic diffusers. The degree of time series fluctuation showed the best correlation with varying diffuser configurations in the low-frequency range. Confidence intervals and coefficients of variation of the three metrics by random sampling also indicated that DTF is more reliable for evaluating the diffuseness in a sound field as it is less influenced by the number of sampling.

Large-amplitude standing-wave fields in standing-wave tube with abrupt cross section

The transfer matrix is used to analyze the properties of a two-step standing-wave tube with abrupt cross-section (STAS). With the STAS, a large-amplitude standing-wave field of 184.7 dB is established at the right end in an improved standing-wave tube experimental system under the excitation at the resonant frequency of the 1st-order peak. Harmonic development at the right and left ends are investigated experimentally for the large-amplitude standing-wave fields obtained under the excitations at the resonant frequencies of the 1st- to 5th-order peak. For comparison, the large-amplitude standing-wave fields excited at the resonant frequencies of the 1st- to 5th-order trough are also studied experimentally in the same way and the large-amplitude standing-wave field of 179.1 dB is obtained at the resonant frequency of the 1st-order trough. For further comparison, the variations of sound pressure level (SPL) and waveform distortion of the fundamental waves at the right and left ends under the excitations at the resonance frequencies of the 1st- to 5th-order peak and trough are also investigated experimentally. Under the same source-driving voltage, the SPL of the fundamental wave at the right end excited at the resonance frequency of the 1st-order peak are higher than the corresponding one at the resonance frequency of the 1st-order trough while forthe waveform distortions, theinverseistrue.

Wind Turbine Noise and Sleep: Pilot Studies on the Influence of Noise Characteristics.

The number of onshore wind turbines in Europe has greatly increased over recent years, a trend which can be expected to continue. However, the effects of wind turbine noise on long-term health outcomes for residents living near wind farms is largely unknown, although sleep disturbance may be a cause for particular concern. Presented here are two pilot studies with the aim of examining the acoustical properties of wind turbine noise that might be of special relevance regarding effects on sleep. In both pilots, six participants spent five consecutive nights in a sound environment laboratory. During three of the nights, participants were exposed to wind turbine noise with variations in sound pressure level, amplitude modulation strength and frequency, spectral content, turbine rotational frequency and beating behaviour. The impact of noise on sleep was measured using polysomnography and questionnaires. During nights with wind turbine noise there was more frequent awakening, less deep sleep, less continuous N2 sleep and increased subjective disturbance compared to control nights. The findings indicated that amplitude modulation strength, spectral frequency and the presence of strong beats might be of particular importance for adverse sleep effects. The findings will be used in the development of experimental exposures for use in future, larger studies.

Treatment of 40 kHz continuous ultrasound towards blood cells of mice (Mus musculus L)

The application of ultrasound in mice has increased the activity of mice and showed anxious behavior that affects the blood cells of mice. This study aims to observe the effect of 40 kHz ultrasound exposure on the content of leukocytes and erythrocytes in blood cells of mice. For this purpose, five ultrasound treatments with sound pressure levels were 70, 75, 80, 85, and 90 dB respectively and one control in six sample groups, each consisting of five mice with the same weight and age. Sound treatment is carried out with a 40 kHz continuous ultrasound exposure of the same duration for two hours. Taking blood samples of mice is carried out as soon as the sample is given a sound treatment. Based on the results of blood tests of mice it was found that the average increase in the number of leukocyte mice varied between 40-1,070 cells/mm3 for variations in sound pressure levels from 70 to 90 dB with an increase in the highest average number of leukocyte (1,070 cells/mm3) at the sound pressure level 75 dB. With the same level of sound pressure level, the decrease in the average number of erythrocytes varied between 920,000-190,000 cells/mm3 with a decrease in the highest average number of erythrocytes (920,000 cells/mm3) at an 80 dB sound pressure level. The optimum level of sound pressure that can affect the average number of leukocytes and erythrocytes in blood cells of mice are still unknown.

Analysis of the effects of uneven sound coverage over a facade during a sound insulation test according to the international standard ISO 16283-3

Building regulations worldwide include specific sections on protection against noise and vibrations, making sound insulation of facades an important part of regulations in many countries. Consequently, sound insulation field tests become important, as a way to certify, or check, if a facade complies with the regulatory requirements. The international standard ISO 16283-3:2016 specifies the procedures and methods to describe the sound insulation of a facade, making the loudspeaker method for the whole facade one of the most widely used because of the advantages it has for practitioners.To make the method consistent, the international standard establishes some constraints, trying to minimize the variation of sound pressure level on the facade. This variation is caused by the directivity of the loudspeaker and the distance from the loudspeaker to the facade, causing an uneven sound coverage over the facade. This paper analyzes and quantifies the solitary influence of facade coverage on the sound insulation determinations in relation to the location of the facade elements. In addition to other influences, the specific location of a small air inlet on a facade can alter the results by up to 4dB, even if the sound coverage complies with the requirements established by the international standard. Finally, an alternative measurement setup is discussed that aims to minimize the negative effect of this phenomenon in an attempt to increase the consistency of the method.

Sound field uncertainty budget for real-ear attenuation at threshold measurement per ANSI S12.6 standards

In many national and international standards, the attenuation of Hearing Protection Devices is rated according to a psychophysical method called Real-Ear Attenuation at Threshold (REAT), which averages on a group of test-subjects the difference between the open and occluded auditory thresholds. In ANSI S12.6 standard, these REAT tests are conducted in a diffuse sound field in which sound uniformity and directionality are assessed by two objective microphone measurements. While the ANSI S12.6 standard defines these two criteria, it does not link the microphone measurements to the actual variation of sound pressure level at the eardrum that may originate from natural head movements during testing. This presentation examines this issue with detailed measurements conducted in an ANSI S12.6-compliant audiometric booth using an Artificial Test Fixture (ATF). The sound pressure level variations were recorded for movements of the ATF along the three main spatial axes and two rotation planes. From these measured variations and different head movements hypothetical scenarios, various sound field uncertainty budgets were computed. These findings will be discussed in order to eventually include them for uncertainty budget in a revised version of the ANSI S12.6 standard.

Noise reduction efficiency of Helmholtz resonator in simulated channel of HVAC system

Aims: The purpose of this article was investigating the efficiency of designing resonator in decreasing low noises. Materials and Methods: The designed Helmholtz resonator was installed in a channel analogous to ventilation channel. The resonator was produced signals at very low frequencies (125-500 Hz) and sound pressure levels 60-90 dB and transmitted through a channel by means of a speaker. Afterwards, the variation of sound pressure level was monitored and then intra-channel signals processing and preparing of sound Algorithm in channel was done by MATLAB software. Results: The highest decrease of sound pressure level at 125 Hz frequency among of Helmholtz resonators was observed at chamber diameter of 63 mm and resonator's 1 cm-caliber. Sound pressure level reductions of 0-10 dB were achieved in an experimental duct system using a Helmholtz resonator. Conclusions: This research showed that the designed Helmholtz resonators at a certain frequency of low-frequency sound demonstrated the soundest decrease. The increase in the Helmholtz resonators' chamber volume and their neck's pass area are negatively associated with the rate of sound resonance. As a result, of determining the effective frequency range of the Helmholtz resonator, the designed resonator could be applied as an effective and efficient instrument of removing or decreasing noise.

Amplitude variation in calibrated audiometer systems in clinical simulations.

Manual pure tone audiometry is considered to be the gold standard for the assessment of hearing thresholds and has been in consistent use for a long period of time. An increased legislative requirement to monitor and screen workers, and an increasing amount of legislation relating to hearing loss is putting greater reliance on this as a tool. There are a number of questions regarding the degree of accuracy of pure tone audiometry when undertaken in field conditions, particularly relating to the difference in conditions between laboratory calibration and clinical or industrial screening use. This study analyzed the output sound pressure level of four different commercial audiometers, all using TDH39 headphones and each of which had recently undergone calibration at an appropriate laboratory. Levels were measured using a Bruël and Kjaer Head and Torso simulator, which accurately replicates the size and shape of a human head, including the ears. A clinical environment was simulated by a trained audiometrist replacing the headphones for each test. Tests were undertaken at three presentation levels, and at the frequencies of 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz and 6 kHz. The results showed a high level of test-retest variability, both between different audiometers and within the same audiometer. Maximum variation of sound pressure level at the ear for the same tone presentation was 21 decibels, with a particularly high level of variation at 6 kHz for all meters. An audiometer with attenuating cups exhibited significantly higher variation than ones using supral-aural headphones. Overall the variation exhibited suggests that there is a higher degree of potential error with screening pure tone audiometry than is commonly assumed and that results particularly at the 6 kHz frequency need to be assessed carefully alongside other methods such as speech audiometry.

Comparison of sound propagation and perception of three types of backup alarms with regards to worker safety

A technology of backup alarms based on the use of a broadband signal has recently gained popularity in many countries. In this study, the performance of this broadband technology is compared to that of a conventional tonal alarm and a multi-tone alarm from a worker-safety standpoint. Field measurements of sound pressure level patterns behind heavy vehicles were performed in real work environments and psychoacoustic measurements (sound detection thresholds, equal loudness, perceived urgency and sound localization) were carried out in the laboratory with human subjects. Compared with the conventional tonal alarm, the broadband alarm generates a much more uniform sound field behind vehicles, is easier to localize in space and is judged slighter louder at representative alarm levels. Slight advantages were found with the tonal alarm for sound detection and for perceived urgency at low levels, but these benefits observed in laboratory conditions would not overcome the detrimental effects associated with the large and abrupt variations in sound pressure levels (up to 15-20 dB within short distances) observed in the field behind vehicles for this alarm, which are significantly higher than those obtained with the broadband alarm. Performance with the multi-tone alarm generally fell between that of the tonal and broadband alarms on most measures.

Pediatric Normative Data for the KayPENTAX Phonatory Aerodynamic System Model 6600

The objectives of this study were to (1) establish a preliminary pediatric normative database for the KayPENTAX Phonatory Aerodynamic System (PAS) Model 6600 (KayPENTAX Corp, Montvale, NJ) and (2) identify whether the data obtained were age- and/or gender-dependent. Prospective data collection across groups. A sample of 60 children (30 females and 30 males) with normal voices was divided into three age groups (6.0-9.11, 10.0-13.11, 14.0-17.11 years) with equal distribution of males and females within each group. Five PAS protocols (vital capacity, maximum sustained phonation, comfortable sustained phonation, variation in sound pressure level, voicing efficiency) were used to collect 45 phonatory aerodynamic measures. Measurements for the 45 PAS parameters examined revealed 13 parameters to have a difference that was statistically significant by age and/or gender. There was a significant age×gender interaction for mean pitch in the four protocols that reported this measure. Males in the oldest group had significantly lower mean pitch values than the middle and young groups. Statistically significant main effect differences were noted for seven parameters across three age groups (expiratory volume, expiratory airflow duration, phonation time, pitch range (in 2 protocols), aerodynamic resistance, acoustic ohms). Significant main effect differences for genders (males>females) were found for expiratory volume and peak expiratory airflow. The age- and gender-related differences found for some parameters within each of the five protocols are important for the interpretation of data obtained from PAS. These results could be explained by developmental changes that occur in the male and female respiratory and laryngeal systems.

Adult Normative Data for the KayPENTAX Phonatory Aerodynamic System Model 6600

The primary purpose of the present study was to establish a preliminary adult normative database for 41 phonatory aerodynamic measures obtained with the KayPENTAX Phonatory Aerodynamic System (PAS) Model 6600 (KayPENTAX Corp, Lincoln Park, NJ). A second purpose was to examine the effect of age and gender on these measures. Prospective data collection across groups. A sample of 157 normal speakers (68 males and 89 females) were divided into three age groups (18-39, 40-59, and 60+ years). The PAS protocols of vital capacity, maximum sustained phonation, comfortable sustained phonation, variation in sound pressure level, and voicing efficiency were used to collect 41 phonatory aerodynamic measures. Comfortable pitch and loudness levels were used with each protocol requiring phonation. A statistically significant main effect of age was found for seven measures, and a statistically significant main effect of gender was found for five measures. The remaining 29 measures did not reach statistical significance; however, 13 of these had high observed power. The remaining 16 measures did not reach significance and had low observed power. Because age- and gender-related changes were found for some measures, one must account for these two variables when assessing phonatory aerodynamics using the PAS Model 6600. The clinical implications of the findings for the assessment and treatment of individuals with voice disorders using the PAS Model 6600 are discussed.

STATISTICAL ASSESSMENT OF ENVIRONMENTAL NOISE GENERATED BY ROAD TRAFFIC / STATISTINIS APLINKOS TRIUKŠMO, SKLINDANČIO NUO KELIŲ TRANSPORTO, ĮVERTINIMAS / СТАТИСТИЧЕСКАЯ ОЦЕНКА ШУМА, ПРОИЗВОДИМОГО АВТОМОБИЛЬНЫМ ТРАНСПОРТОМ

Abstract The necessity to check requirements for sound insulation of new building facades against outdoor noise and for estimating noise pollution of the residential area comprise the assessment of environmental noise taking in situ measurements that are mainly carried out under the standardized method presented in the EU directives and Lithuanian legislation. For these estimations, annual composite daily equivalent sound pressure level Ldеn becomes obligatory. When the value of this descriptor is determined from measurements, it is relevant to reasonably reduce a time interval of the performed measurement. The possibilities of determining the noise level Ld ,12h of the day (12h) undertaking annual Lden assessment making short-term (15÷60 min.) measurements is dealt in this work. In this way, the sensitivity of the set of statistical descriptors to variations in sound pressure levels was investigated. The paper proposes that the obtained instantaneous A-weighted sound pressure levels with F (fast) time we...

A preliminary investigation into the association between body movement patterns and dynamic variation in western contemporary popular singing

This study assessed the presence of body movements that may be common to all western contemporary popular (WCP) singers that may be integral to both the physical production of the sung sound and to acoustic output, in this case sound pressure level variation. Since torso movement appears to be closely linked with dynamic variation in this style of singing, the study focused on the activity of the torso. 3-D video footage of the body movements of six professional WCP singers singing the same R & B song was collected. Antero-posterior (AP) torso movement direction frequency and characteristics at the point of maximum sustained SPL and fO (peak note) on the vowel /ε/ were analysed. The most common movement of the torso was in a posterior direction, reaching its point of maximum displacement from the starting position on the peak note. Strong anterior torso movement on the peak note, which took the torso forward of its anatomical position was associated with the head forward position and vocal distortion, indicating that this movement at a point of high SPL may present a vocal health risk. These results indicate that the AP torso movement of WCP singers has a function in voice production and that not only body posture but the manner of movement from one body position to another is significant to vocal health and sound production, especially in styles where high sound levels must be achieved and where a high level of body movement is required in performance.

Effect of lining non-linearity on realized attenuation of tonal noise

An iterative model based on an FEM propagation code is introduced for prediction of attenuation in a duct in the presence of a two degree of freedom acoustic lining for which impedance depends on local grazing flow speed and overall local Sound Pressure Level. A general approach is described; however this investigation is limited to the case of a source Sound Pressure Level spectrum dominated by a single tone for which the lining is optimized. The tone is specified by its circumferential mode and a statistically represented radial modal amplitude distribution. It is assumed that the underlying broad band spectrum is diffuse and relatively unaffected by the lining. Lining impedance is computed locally and is described by an iterative model imbedded in the propagation code. It is determined how local variation of Sound Pressure Level affects realized attenuation by comparing attenuation predictions when impedance depends on source Sound Pressure Level and when impedance depends on local Sound Pressure Level. Predicted attenuation is dependent on local variation in lining impedance when the tone level is significantly above the overall broadband level. When suppression of the tone has little effect on the overall Sound Pressure Level there is little effect of local impedance variation on attenuation.

Reprint of: Effect of lining non-linearity on realized attenuation of tonal noise

An iterative model based on an FEM propagation code is introduced for prediction of attenuation in a duct in the presence of a two degree of freedom acoustic lining for which impedance depends on local grazing flow speed and overall local Sound Pressure Level. A general approach is described; however this investigation is limited to the case of a source Sound Pressure Level spectrum dominated by a single tone for which the lining is optimized. The tone is specified by its circumferential mode and a statistically represented radial modal amplitude distribution. It is assumed that the underlying broad band spectrum is diffuse and relatively unaffected by the lining. Lining impedance is computed locally and is described by an iterative model imbedded in the propagation code. It is determined how local variation of Sound Pressure Level affects realized attenuation by comparing attenuation predictions when impedance depends on source Sound Pressure Level and when impedance depends on local Sound Pressure Level. Predicted attenuation is dependent on local variation in lining impedance when the tone level is significantly above the overall broadband level. When suppression of the tone has little effect on the overall Sound Pressure Level there is little effect of local impedance variation on attenuation.

The sound field in life‐size replicas of human ear canals occluded by a hearing aid

In addition to the longitudinal sound pressure distributions that form in the human ear canal, large transverse variations can arise in the vicinity of an occluding hearing aid. These effects are being studied, numerically and experimentally, making use of life‐size ear canal replicas. Using digital representations of real ear canal geometries [Stinson and Lawton, J. Acoust. Soc. Am. 85, 2492‐2503 (1989)], a polyjet fabrication process forms replicas with a spatial accuracy of better than 0.1 mm. A hearing aid test fixture, with vent, receiver, and an inner microphone, occludes the replica canal and provides the acoustical input. The sound field inside the canal is measured using a 0.2 mm o.d. probe microphone. In parallel, the interior sound field is calculated using a boundary element method, using the same ear canal geometry as the replicas and accounting for the acoustical boundary conditions presented by the eardrum and the hearing aid. In the current series of ear canal replicas, the eardrum is rigid. Measurements and calculations are in good agreement. Large transverse variations of sound pressure level, as much as 20 dB at 8 kHz, are observed across the inner face of the hearing aid, particularly near the receiver and vent ports.

Improving room acoustics at low frequencies with multiple loudspeakers and time based room correction

Small and medium size rectangular rooms are often used for sound reproduction. These rooms have substantial acoustical problems at low frequencies primarily caused by the reflections from the room boundaries. The spatial variation in sound pressure level (SPL) can be up to 30 dB in a room at low frequencies, and appear not only at modal frequencies. The problem is an acoustical issue in time, and should therefore be analyzed in the time-domain, instead of the traditional steady state frequency domain. The construction of a finite-difference time-domain approximation program (FDTD) has lead to a simple and untraditional solution called CABS (Controlled Acoustical Bass System) that makes use of multiple loudspeakers. With the proper placement of low frequency loudspeakers, CABS can create a plane wave from the front wall which will be absorbed by additional low frequency loudspeakers at the back wall. With the back wall reflection removed a homogeneous sound field will be created in the whole room at low frequencies. Simulations and measurements of normal size listening rooms show that 4 loudspeakers are enough to even the sound field in a room. The CABS system is controlled by a developed DSP system.