The acoustic characteristics of the “Dives in Misericordia” Church in Rome

2020 ◽  
pp. 1351010X2094865
Author(s):  
Giuseppe Ciaburro ◽  
Gino Iannace ◽  
Amelia Trematerra ◽  
Ilaria Lombardi ◽  
Maurizio Abeti
Keyword(s):  
Side Wall ◽  
Sound Field ◽  
Reverberation Time ◽  
Acoustic Measurements ◽  
Internal Length ◽  
Maximum Width ◽  
Acoustic Characteristics ◽  
Current Configuration ◽  
Double Curve ◽  
The Church

This paper discusses the acoustic characteristics of the “Dives in Misericordia” Church in Rome. The church was designed by architect Richard Meier and opened in 2003. It was made entirely of white concrete and consists of three septa with a double curve shaped like a sail. The nave roof is glass. The volume is approximately 14.000 cubic meters. The highest measuring is approximately 26 m. the width of the nave is 19.5 m, while the maximum width is 29.5 m, while the internal length is 32.0 m, while the total length is 45.6 m. It can seat approximately 240 people. The acoustic measurements were taken by placing a microphone at different points of the nave (the area occupied by the audience), with the sound source being placed on the altar. It was therefore possible to obtain a spatial distribution of the average acoustic characteristics inside the church. At a frequency of 1000 Hz, the average values of the reverberation time is about 10 s. In its current configuration, the church is neither suitable for understanding speech nor listening to music. A 3D virtual model was created and with the help of the building acoustics software it was possible to study the sound field inside the church. The possibility to carry out an appropriate acoustic correction was analyzed, in order to reduce the values of the reverberation time, by pacing on a side wall of the church an adequate number of sound-absorbing polyester panels.

Design and Construction of a Small Reverberation Chamber Applied to Absorption and Scattering Acoustic Measurements

2014 ◽  
Vol 1077 ◽  
pp. 197-202
Author(s):  
D. Hernandez ◽  
E.J. Liu ◽  
J.H. Huang ◽  
Y.C. Liu
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Sound Field ◽  
Acoustic Measurements ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Scattering Coefficients ◽  
Reverberation Chambers ◽  
The Cost ◽  
Design And Construction

Reverberation chambers are used to create a diffuse incidence sound field, where multiple types of acoustic measurements can be performed. The chambers tend to have a large volume in order to extent the reverberation time. However, this requirement may be conditioned by the cost and the infrastructure limitations. This paper presents the design and construction of a small-scaled reverberation chamber of 3 m3 for middle-high frequency acoustic measurements. On the design, the acoustic characteristics of chamber are confirmed via finite element computer simulation. As case studies, absorption and scattering coefficients of several materials and diffusors are measured. The reverberation times needed for the measurements were obtained by the impulse response integration method. The small reverberation chamber demonstrated to be a reliable tool for middle and high frequency acoustic measurements.

scholarly journals EFFICIENT ACOUSTIC COMPOSITE PANELS BASED ON GRAPHITE

2021 ◽  
Vol 6 (4) ◽  
pp. 82-90
Author(s):  
E. Fanina
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Sound Field ◽  
Fire Retardant ◽  
Pyramidal Cells ◽  
Sound Insulation ◽  
Composite Panels ◽  
Thin Membrane ◽  
Reverberation Time ◽  
Acoustic Characteristics

A set of experimental studies is carried out to determine the acoustic characteristics of three-dimensional panels of fixed thickness made of carbon-based composite material installed in the opening between the reverberation chambers. Sound insulation indices are determined when they are excited by a diffuse sound field in wide frequency ranges. The reverberation time in model chambers with different partition configurations is calculated. The optimal configuration of the partition with pyramidal cells to reduce the reverberation time in the rooms is determined. The use of graphite in the form of thin membrane applied to various surfaces can significantly reduce the sound pressure levels in the room and increase the sound insulation indices of air noise. In addition to thin membrane, graphite can be used as an additive in composite materials for sound insulation purposes. It is shown that the characteristics of such panels are quite universal. The measured acoustic characteristics of composite panels are compared with similar characteristics of traditional materials. It is determined that the composition belongs to the I group of fire-retardant efficiency and can be recommended for use as a fire-retardant material. The developed acoustic material is an effective absorbing agent that solves problems in architectural acoustics, echo cancellation in construction and architecture. Similar to metamaterials, natural and artificial graphites allow to solve these problems with small volumes and masses using simple and inexpensive technologies.

The acoustics of ancient catacombs in Southern Italy

2020 ◽  
pp. 1351010X2096757 ◽  
Author(s):  
Giuseppe Ciaburro ◽  
Umberto Berardi ◽  
Gino Iannace ◽  
Amelia Trematerra ◽  
Virginia Puyana-Romero
Keyword(s):  
Roman Empire ◽  
Sound Source ◽  
Southern Italy ◽  
Reverberation Time ◽  
Acoustic Measurements ◽  
Acoustic Characteristics ◽  
Christian Religion ◽  
Renaissance Period ◽  
Transmission Index ◽  
Speech Transmission

The catacombs, burial sites for early Christians, were constructed during the Roman Empire until the Christian religion was recognized in 313 AD. The catacombs were cementeries, which were organized according to precise rules and were dug into the ground on several levels, to occupy as little space as possible. The catacombs became places of worship as martyrs were buried in them. The catacombs were then abandoned with the barbarian invasions and the consequent construction of churches inside cities. The catacombs were rediscovered during the Renaissance period and became a place of renewed worship. In the present work, the acoustic characteristics of the catacombs of San Callisto in Rome, San Gennaro in Naples, and Vigna Cassia in Syracuse are discussed. The three selected catacombs differ by type of excavation and geometry. In particular, the catacombs of San Callisto are made of narrow corridors and small rooms; the catacombs of San Gennaro consist of large rooms with niches; the catacombs of Vigna Cassia are partly excavated in the tuff and partially occupy a disused aqueduct. The acoustic measurements were performed using an impulsive sound source. The description of the acoustic characteristics focuses on the reverberation time and the Speech Transmission Index. The results show that the reverberation time was always shorter than 1 second, confirming the reduced reverberation of these environments. Finally, the speech listening characteristics are particularly good, ensuring the suitable conditions for the prayer in these spaces.

scholarly journals OPTIMIZATION OF REVERBERATION CHAMBER PARAMETERS FOR ACOUSTIC TESTS OF BUILDING CONSTRUCTION

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 53-58
Author(s):  
Alexandra Baldina ◽  
Lilia Pastukhova ◽  
Antonina Sekacheva
Keyword(s):  
Sound Pressure ◽  
Decay Curve ◽  
Pearson Correlation ◽  
Sound Field ◽  
Building Construction ◽  
Reverberation Time ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Four Levels ◽  
High Level

The work is devoted to the study of the acoustic characteristics of reverberation chamber. Sound pressure measurements have been carried out to study the sound field in low and high level rooms of reverberation chamber. To determine the diffuse field of sound, the sound pressure was measured at points uniformly distributed over the area of the chambers at four levels in height. The reverberation time was studied using the method of interrupted noise and fixing the decay curve by the measuring instrument. To establish the characteristic correlation between the sound pressure level at the measuring points and the distance to the sound source, the Pearson correlation coefficient was calculated. The degree of influence of the finishing room on the amount of reverberation time was investigated.

Computational studies of steady-state sound field and reverberant sound decay in a system of two coupled rooms

Open Physics ◽  
2007 ◽  
Vol 5 (3) ◽  
Author(s):  
Mirosław Meissner
Keyword(s):  
Steady State ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Coupled System ◽  
Reverberation Time ◽  
Acoustic Characteristics ◽  
Acoustical Properties ◽  
Forced Oscillator ◽  
Calculation Results

AbstractThe acoustical properties of an irregularly shaped room consisting of two connected rectangular subrooms were studied. An eigenmode method supported by a numerical implementation has been used to predict acoustic characteristics of the coupled system, such as the distribution of the sound pressure in steady-state and the reverberation time. In the theoretical model a low-frequency limit was considered. In this case the eigenmodes are lightly damped, thusthey were approximated by normal acoustic modes of a hard-walled room. The eigenfunctions and eigenfrequencies were computed numerically via application of a forced oscillator method with a finite difference algorithm. The influence of coupling between subrooms on acoustic parameters of the enclosure was demonstrated in numerical simulations where different distributions of absorbing materials on the walls of the subrooms and various positions of the sound source were assumed. Calculation results have shown that for large differences in the absorption coefficient in the subrooms the effect of modal localization contributes to peaks of RMS pressure in steady-state and a large increase in the reverberation time.

scholarly journals ACOUSTIC CHARACTERISTICS OF PULSED SOUND SOURCES OF VARIOUS TYPES/ĮVAIRIŲ TIPŲ IMPULSINIŲ GARSO ŠALTINIŲ AKUSTINĖS CHARAKTERISTIKOS

1998 ◽  
Vol 4 (4) ◽  
pp. 311-315 ◽  
Author(s):  
Vytautas Stauskis ◽  
Vytautas Kunigėlis
Keyword(s):  
Pulse Duration ◽  
Sound Source ◽  
Short Pulse ◽  
Sound Field ◽  
Correct Selection ◽  
Sound Sources ◽  
Major Drawback ◽  
Maximum Width ◽  
Acoustic Characteristics ◽  
Sound Energy

The paper examines the acoustic characteristics of explosion-type pulsed sound sources of four types. These include a Calibre 8 sound gun, a start gun, a Calibre 16 hunting gun, and a toy gun. The latter was included both because of its short pulse duration and for comparison purposes. Correct selection of a source is very important because it largely determines the results of acoustic measurements. Certain requirements are set for a sound source. In order to concentrate as much energy as possible at the given moment, the signal bandwidth-duration product must be as large as possible. The range frequencies to be excited depend on the pulse duration. The latter also determines whether interference phenomena will occur in the room and whether individual reflections will merge. The experiments were conducted in a room of 12 m2. The distance between the microphone and the pulsed sound source was 1 m. The structure of reflections depends on the pulse by means of which the sound field is excited. The smallest number of reflections is generated by a sound source. During a 20 ms experiment, the amplitudes of these reflections almost coincided with the direct sound amplitude. A sound gun emits more sound energy than other pulses. When the sound field is excited by means of a start gun and a hunting gun, the reflection structure, by amplitude, is very different from that produced by a sound gun. A dense reflection structure is formed by a toy gun but it emits less energy. The structure of reflections generated by a hunting gun is acceptable but its shots are very unstable, which is a major drawback in an experiment. The shots from a sound gun differ only by about 0.1% among themselves by amplitude, ie they are sufficiently stable. Among the four sound sources, the best reflection structure is produced by a sound gun. A sound gun is characterised both by the longest pulse duration (about 0.55 ms) and the highest levels of energy emitted. The pulse duration of the rest three guns is almost equal and is about 0.15 ms, ie is 3.6 times shorter than that of a sound gun. The forms of signals emitted by these sound sources are also very different. The spectrum of a sound source was established on Fourier transformation basis. The spectrum is largely dependent on the type of a gun by means of which the sound field is excited. The maximum width of the spectrum generated by a sound gun occupies almost two octaves, from 500 to 2000 Hz, and the radiation in this range is quite uniform. The spectra of a start gun and a hunting gun are similar but these guns emit less sound energy than a sound gun. The structure of reflections generated by them is also quite different. A toy gun radiates energy in a less narrower band, the width of which occupies about a half of octave, with a maximum at 2000 Hz. This is not very good because too small quantities of low- and medium-frequency sound energy are radiated.

Study on acoustic and flow-induced noise characteristics of L-shaped duct with a shallow cavity

2020 ◽  
Vol 68 (3) ◽  
pp. 209-225
Author(s):  
Masaaki Mori ◽  
Kunihiko Ishihara
Keyword(s):  
Air Conditioning ◽  
Sound Field ◽  
Frequency Range ◽  
Acoustic Characteristics ◽  
Inflow Velocity ◽  
Aerodynamic Sound ◽  
Noise Characteristics ◽  
Flow Induced Noise ◽  
Shallow Cavity ◽  
Conditioning Equipment

An aerodynamic sound generated by a flow inside a duct is one of the noise pro- blems. Flows in ducts with uneven surfaces such as grooves or cavities can be seen in various industrial devices and industrial products such as air-conditioning equipment in various plants or piping products. In this article, we have performed experiments and simulations to clarify acoustic and flow-induced sound characteris- tics of L-shaped duct with a shallow cavity installed. The experiments and simula- tions were performed under several inflow velocity conditions. The results show that the characteristics of the flow-induced sound in the duct are strongly affected by the acoustic characteristics of the duct interior sound field and the location of the shallow cavity. Especially, it was found that the acoustic characteristics were af- fected by the location of the shallow cavity in the frequency range between 1000 Hz and 1700 Hz.

General Theory of the Energy Relations in Halls with Asymmetrical Absorption

1998 ◽  
Vol 5 (3) ◽  
pp. 163-183 ◽  
Author(s):  
Higini Arau
Keyword(s):  
General Theory ◽  
Uniform Distribution ◽  
Decay Time ◽  
Sound Field ◽  
Reverberation Time ◽  
Sound Energy ◽  
Method Of Calculation ◽  
New Energy ◽  
Energy Relations

In this paper we describe a method of calculation of the energy relations in halls where the existence of a non-uniform distribution of absorptive material in the room results in a non-diffuse sound field. The cases of halls used for concerts and speech have both been treated in order to derive new energy relations that yield known expressions when applied to a diffuse sound field. The importance of the initial reverberation time corresponding to the first portion of the decay has been verified showing that the main subjective parameters relating to the sound energy are influenced strongly by this portion, which is called the Early Decay Time if it is measured in the first 10 dB of the decay.

scholarly journals THE PECULIARITIES OF THE SOUND FIELD ENERGY DECAY IN A ROOM WITH THE USE OF DIFFERENT PULSED SOUND SOURCES/GARSO LAUKO ENERGIJOS SLOPIMO PATALPOJE YPATUMAI, NAUDOJANT SKIRTINGUS IMPULSINIUS GARSO ŠALTINIUS

1999 ◽  
Vol 5 (2) ◽  
pp. 135-140
Author(s):  
Vytautas Stauskis
Keyword(s):  
Noise Level ◽  
Sound Field ◽  
Maximum Energy ◽  
Reverberation Time ◽  
Frequency Range ◽  
Sound Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Difference ◽  
Field Decay

The paper deals with the differences between the energy created by four different pulsed sound sources, ie a sound gun, a start gun, a toy gun, and a hunting gun. A knowledge of the differences between the maximum energy and the minimum energy, or the signal-noise ratio, is necessary to correctly calculate the frequency dependence of reverberation time. It has been established by investigations that the maximum energy excited by the sound gun is within the frequency range of 250 to 2000 Hz. It decreases by about 28 dB at the low frequencies. The character of change in the energy created by the hunting gun differs from that of the sound gun. There is no change in the maximum energy within the frequency range of 63–100 Hz, whereas afterwards it increases with the increase in frequency but only to the limit of 2000 Hz. In the frequency range of 63–500 Hz, the energy excited by the hunting gun is lower by 15–30 dB than that of the sound gun. As frequency increases the difference is reduced and amounts to 5–10 dB. The maximum energy of the start gun is lower by 4–5 dB than that of the hunting gun in the frequency range of up to 1000 Hz, while afterwards the difference is insignificant. In the frequency range of 125–250 Hz, the maximum energy generated by the sound gun exceeds that generated by the hunting gun by 20 dB, that by the start gun by 25 dB, and that by the toy gun—by as much as 35 dB. The maximum energy emitted by it occupies a wide frequency range of 250 to 2000 Hz. Thus, the sound gun has an advantage over the other three sound sources from the point of view of maximum energy. Up until 500 Hz the character of change in the direct sound energy is similar for all types of sources. The maximum energy of direct sound is also created by the sound gun and it increases along with frequency, the maximum values being reached at 500 Hz and 1000 Hz. The maximum energy of the hunting gun in the frequency range of 125—500 Hz is lower by about 20 dB than that of the sound gun, while the maximum energy of the toy gun is lower by about 25 dB. The maximum of the direct sound energy generated by the hunting gun, the start gun and the toy gun is found at high frequencies, ie at 1000 Hz and 2000 Hz, while the sound gun generates the maximum energy at 500 Hz and 1000 Hz. Thus, the best results are obtained when the energy is emitted by the sound gun. When the sound field is generated by the sound gun, the difference between the maximum energy and the noise level is about 35 dB at 63 Hz, while the use of the hunting gun reduces the difference to about 20–22 dB. The start gun emits only small quantities of low frequencies and is not suitable for room's acoustical analysis at 63 Hz. At the frequency of 80 Hz, the difference between the maximum energy and the noise level makes up about 50 dB, when the sound field is generated by the sound gun, and about 27 dB, when it is generated by the hunting gun. When the start gun is used, the difference between the maximum signal and the noise level is as small as 20 dB, which is not sufficient to make a reverberation time analysis correctly. At the frequency of 100 Hz, the difference of about 55 dB between the maximum energy and the noise level is only achieved by the sound gun. The hunting gun, the start gun and the toy gun create the decrease of about 25 dB, which is not sufficient for the calculation of the reverberation time. At the frequency of 125 Hz, a sufficiently large difference in the sound field decay amounting to about 40 dB is created by the sound gun, the hunting gun and the start gun, though the character of the sound field curve decay of the latter is different from the former two. At 250 Hz, the sound gun produces a field decay difference of almost 60 dB, the hunting gun almost 50 dB, the start gun almost 40 dB, and the toy gun about 45 dB. At 500 Hz, the sound field decay is sufficient when any of the four sound sources is used. The energy difference created by the sound gun is as large as 70 dB, by the hunting gun 50 dB, by the start gun 52 dB, and by the toy gun 48 dB. Such energy differences are sufficient for the analysis of acoustic indicators. At the high frequencies of 1000 to 4000 Hz, all the four sound sources used, even the toy gun, produce a good difference of the sound field decay and in all cases it is possible to analyse the reverberation process at varied intervals of the sound level decay.

Quantifying Non-Linearity in Early Decay Curves of Measured and Computer-Modeled Room Impulse Responses of a Highly Non-Diffuse Room Exhibiting Flutter Echo

2020 ◽  
Author(s):  
Heather L. Lai ◽  
Brian Hamilton
Keyword(s):  
Linear Regression ◽  
Computer Modeling ◽  
Impulse Response ◽  
Decay Curve ◽  
Sound Field ◽  
Energy Decay ◽  
Room Acoustics ◽  
Reverberation Time ◽  
Sound Fields ◽  
Regression Curves

Abstract This paper investigates the use of two room acoustics metrics designed to evaluate the degree to which the linearity assumptions of the energy density curves are valid. The study focuses on measured and computer-modeled energy density curves derived from the room impulse response of a space exhibiting a highly non-diffuse sound field due to flutter echo. In conjunction with acoustical remediation, room impulse response measurements were taken before and after the installation of the acoustical panels. A very dramatic decrease in the reverberation time was experienced due to the addition of the acoustical panels. The two non-linearity metrics used in this study are the non-linearity parameter and the curvature. These metrics are calculated from the energy decay curves computed per octave band, based on the definitions presented in ISO 3382-2. The non-linearity parameter quantifies the deviation of the EDC from a straight line fit used to generated T20 and T30 reverberation times. Where the reverberation times are calculated based on a linear regression of the data relating to either −5 to −25 dB for T20 or −5 to −35 dB for T30 reverberation time calculations. This deviation is quantified using the correlation coefficient between the energy decay curve and the linear regression for the specified data. In order to graphically demonstrate these non-linearity metrics, the energy decay curves are plotted along with the linear regression curves for the T20 and T30 reverberation time for both the measured data and two different room acoustics computer-modeling techniques, geometric acoustics modeling and finite-difference wave-based modeling. The intent of plotting these curves together is to demonstrate the relationship between these metrics and the energy decay curve, and to evaluate their use for quantifying degree of non-linearity in non-diffuse sound fields. Observations of these graphical representations are used to evaluate the accuracy of reverberation time estimations in non-diffuse environments, and to evaluate the use of these non-linearity parameters for comparison of different computer-modeling techniques or room configurations. Using these techniques, the non-linearity parameter based on both T20 and T30 linear regression curves and the curvature parameter were calculated over 250–4000 Hz octave bands for the measured and computer-modeled room impulse response curves at two different locations and two different room configurations. Observations of these calculated results are used to evaluate the consistency of these metrics, and the application of these metrics to quantifying the degree of non-linearity of the energy decay curve derived from a non-diffuse sound field. These calculated values are also used to evaluate the differences in the degree of diffusivity between the measured and computer-modeled room impulse response. Acoustical computer modeling is often based on geometrical acoustics using ray-tracing and image-source algorithms, however, in non-diffuse sound fields, wave based methods are often able to better model the characteristic sound wave patterns that are developed. It is of interest to study whether these improvements in the wave based computer-modeling are also reflected in the non-linearity parameter calculations. The results showed that these metrics provide an effective criteria for identifying non-linearity in the energy decay curve, however for highly non-diffuse sound fields, the resulting values were found to be very sensitive to fluctuations in the energy decay curves and therefore, contain inconsistencies due to these differences.

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