Traffic noise measurement and analysis in Jeddah

This paper presents measurements and analysis of traffic noise in the residential area of Jeddah City. These measurements are aimed to help in predicting the subjective response to noise as a function of measured predicted sound levels. $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$ and $\text{L}{}_{\mathrm{<mtext>90</mtext>}}$ were predicted for different sites, the traffic noise index and the noise pollution index, L_NP, were estimated. Noise data were correlated to the individual respondent's reaction. Linear regression analyses were performed between noise exposure and dissatisfaction response.     

Use of a digital voltmeter to measure the output of a sound level meter

The use of a digital voltmeter and associated computer program to measure the varying output of a sound level meter is discussed. The computer program converts the voltmeter readings into sound levels and calculates quantities such as $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{eq}}$, etc. Using the dc output of a sound level meter, the dynamic range is about 25 dB. This increases to at least 45 dB on the ac output. In general, values found for $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{eq}}$, etc. are within 1 dB of results obtained by other methods.     

Distribution display attachment for a sound level meter

The use of a sound level meter to estimate $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$ and $\text{L}{}_{\mathrm{<mtext>90</mtext>}}$ for a small number of noise samples has appealed to many users as being simple, effective and economical. The more conventional ways of using a statistical distribution analyser or a community noise analyser are justifiable only with a large number of samples and over extended periods. This paper describes a recent development—a portable sound level meter attachment—which is aimed at eliminating the need for accurate meter reading. In the attachment, intermittent noise levels grouped in 3 dB classes are displayed by an array of LED's. Data recording is reduced to registering the occurrences of flash from each LED. When used on traffic noise this method gives values of $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>90</mtext>}}$ and $\text{L}{}_{\mathrm{eq}}$ within 0·7 dB(A) of values obtained by a Bruel and Kjaer type 4426 Statistical Analyser. It is found that this method is most accurate for noise with a high level of fluctuation.     

Environmental acoustic quality in Jeddah urban sites

Surveys of physical exposure to noise at urban sites in Jeddah city indicate that noise from road traffic is very intensive. Relatively high instant sound levels (90 dB(A) and higher) were recorded on a numbr of congested, as well as freely-flowing traffic, roads. Values of the statistical indicators $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>90</mtext>}}$ and $\text{L}{}_{\mathrm{<mtext>dn</mtext>}}$ were determined for indoor domestic noise and comparisons with current western standards show that the levels determined exceeded the limits of dissatisfaction given by those standards. Overall sound pressure levels measured inside typical university offices indicate that the presence of individual room-units of air-conditioning impairs the acoustic quality in those environments. The results of a social survey on noise perception in residential areas are in good agreement with the above findings, indicating that 89 per cent of people interviewed were substantially disturbed by traffic noise. The results of this research, however, demonstrate the necessity for the application of a traffic noise control programme on Jeddah main roads and also the need for attention to be paid to the indoor acoustic quality of homes and offices.     

Statistical analysis from a sound level meter

Increasingly, and particularly for motorway noise, sound level meters are being used to estimate $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$, the noise level just exceeded for 10 per cent of the time, by noting the meter readings at regular intervals and manually analysing the array of data so obtained. In this paper we describe a simple attachment to a sound level meter, which is intended to ease the operator's task in making such measurements and to minimise operator bias. Comparisons are made between the results of sound level meter measurements of three types of noise and the results obtained using the more conventional technique which employs a level recorder and statistical analyser.It is concluded that, at least for motorway noise, the sound level meter technique gives values of $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$ and of $\text{L}{}_{\mathrm{<mtext>90</mtext>}}$ within 1 dB(A) of the values obtained by the normal method. Furthermore, it is probable that the technique will be useful for the measurement of other types of noise in statistical terms, but further investigations of accuracy are required.     

Nonlinear first sound response of liquid helium at 1, 3 and 10 MHz

The first sound response of liquid helium at 1, 3 and 10 MHz is studied using piezoelectric ceramic transducers. Above specific threshold displacement amplitudes, subharmonic frequencies ($\text{?}{}_0\text{2}$, $\text{?}{}_0\text{3}$,…) and ultraharmonic frequencies ($\text{3?}{}_0\text{2}$, $\text{5?}{}_0\text{2}$,…) appear in the response spectrum. The magnitude of the threshold displacement amplitudes for the production of subharmonics suggests that vapor microbubble oscillation appears not to be the primary generation mechanism.     

Estimates of annoyance of sounds of different character

The character of a sound is defined as the weighted combination of all acoustic factors, not contained in $\text{L}{}_{\mathrm{<mtext>A</mtext>}}$, contributing to its annoyance.From this definition it follows that differences in annoyance due to sounds with equal $\text{L}{}_{\mathrm{<mtext>A</mtext>}}$ are differences in sound character. For the concept of sound character to have real significance it is necessary that listeners agree on the annoyance due to sounds with equal $\text{L}{}_{\mathrm{<mtext>A</mtext>}}$.This paper describes a listening experiment with a variety of sounds of equal $\text{L}{}_{\mathrm{<mtext>A</mtext>}}$. The annoyance due to the sounds was rated by twelve subjects. Their individual ratings show significant agreement. Moreover, their average rating correlates well (0·90) with the ratings obtained by Terhardt and Stoll in a similar experiment.     

Evidence for Mn clustering in dilute CuMn alloys from high-field (40 T) magnetization curves at 4.2 K

Magnetization curves of CuMn alloys with Mn concentration between 1.5 and 10 at.% have been measured at 4.2 K in fields up to 40 T, using a pulsed-field method.The results found for different concentrations can be scaled upon one another, which is a clear indication for the occurance of magnetic clusters. Analysis of this universal curve in terms of Brillouin functions yields the values $\text{z}{}_{\mathrm{I}}\text{J}{}_{\mathrm{I}}\text{/k??44K}$, $\text{z}{}_{\mathrm{II}}\text{J}{}_{\mathrm{II}}\text{/k??10K}$ and $\text{z}{}_{\mathrm{III}}\text{J}{}_{\mathrm{III}}\text{/k??0.5K}$, for the largest three interactions within each cluster.     

Low wavenumber wall pressure measurements using a rectangular membrane as a spatial filter

The response of a rectangular membrane to a convecting random pressure field is interpreted to reveal the inherent wavenumber filtering characteristics of the device. After experimental determination of its resonant response characteristics, one such membrane is used to measure the low wavenumber components of the wall pressure fluctuations beneath a plane turbulent boundary layer. The measurements were made at wavenumbers far below the convective region (k₁ = ω/U_c) but above the acoustic region (k₁ ? ω/c_o). Possible contamination by acoustic and convective ridge effects is considered. The low wavenumber measurements are also compared with values of the wavenumber-frequency pressure spectral density $\text{Φ}{}_{\mathrm{p}}\text{(}\text{k}\text{,ω)}$ obtained by Fourier transforming cross-spectral density data obtained by Blake in the same wind tunnel. From this comparison it is seen that this transformation of Blake's data (based on a Corcos model) grossly overestimates the magnitude of $\text{Φ}{}_{\mathrm{p}}\text{(}\text{k}\text{,ω)}$ in the low-wavenumber region. The measured values of $\text{Φ}{}_{\mathrm{p}}\text{(}\text{k}\text{, c}{}_{\mathrm{o}}\text{)}$ are about 36 dB down from convective ridge levels at the same frequency. The data are also compared with earlier results obtained by Jameson. In a similar frequency range the current data levels are approximately 10 dB higher than those of Jameson.     

The barrier attenuation of garden fences

A study has been undertaken of the barrier attenuation produced by 40 different finite garden fences shielding suburban homes from traffic noise. Two alternative techniques of measuring barrier attenuation were used and an empirical relationship between the results is obtained. The attenuation measured in terms of $\text{L}{}_{\mathrm{<mtext>1</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$ or $\text{L}{}_{\mathrm{eq}}$ generally agrees within ± 1 dB(A) for a given barrier. Similarly constructed fences can produce different attenuations, depending on their surroundings. The effects of unshielded ends, open gates and vegetation are considered. It is postulated that buildings reflect back sound, the effect depending on building size and distance from the fence. A reasonable trend is obtained for brick barriers; however, the wooden fence results may be obscured by sound leakage through the fence.     

Stochastic saturation of three-drift-wave interaction at finite parallel wavelength

The interaction of three drift waves is considered at finite parallel wavelength. The coupling to ion sound waves has a profound effect on the saturation levels. For k_|L_n～ 1. turbulent amplitudes are of the magnitude $\text{eΦ?T}{}_{\mathrm{e}}\text{～}\text{1}\text{k}{}_{\mathrm{\perp }}\text{L}{}_{\mathrm{n}}$ as predicted by usual estimates, in contrast to previous studies neglecting this effect.     

Equivalent level of railroad noise with and without barrier

This paper presents models for predicting the equivalent level, $\text{L}{}_{\mathrm{<mtext>eq</mtext>}}$ of railroad noise. For open terrain two cases are considered: with and without ground effects (second section). On the assumption that, at a given point, $\text{L}{}_{\mathrm{<mtext>eq</mtext>}}\text{= L}{}_{\mathrm{<mtext>eq</mtext>}}{}^{\mathrm{*}}$ is required, the problems of barrier length, height and position are discussed (third section). Examples of the application of presented theories are given.     

Diffusion processes and atomic collisions of Na-rare gas systems studied by laser induced population grating method

Diffusion processes and atomic collisions of Na-He and Na-Ar systems have been studied by measurement of the time development of population gratings (Laser-Induced Population Grating; LIPG) induced in atomic levels by two intersecting resonant laser pulses and monitored through the Bragg diffraction of a probe laser beam. The diffusion process in the systems was observed through the decay of the LIPGs in the sodium ground-state $\text{(3}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}$ sublevels. The pressure dependence of the diffusion constants were measured. The values showed rough agreement with the previously reported values which had been measured indirectly by the optical-pumping method. The gaussian process model and a simple collision kernel model were considered for the diffusion process. It was also found that with increasing buffer-gas pressure, the population gratings in the excited state $\text{3}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ were transferred to $\text{3}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, which was interpreted as an effect of fine-structure state-changing collisions.     

Combination tones in the response of single degree of freedom systems with quadratic and cubic non-linearities

The method of multiple scales is used to analyze the response of a single-degree-of-freedom system to either the combination resonance of the additive type $\text{Ω}{}_2\text{+ Ω}{}_1\text{≈ ω}{}_0$ or the combination resonance of the difference type $\text{Ω}{}_2\text{? Ω}{}_1\text{≈ ω}{}_0$, where $\text{Ω}{}_1$ and $\text{Ω}{}_2$ are the frequencies of the excitation and ω₀ is the linear undamped natural frequency of the system. To the second approximation, the combination resonance of the additive type has three effects on the steady state response. First, it produces terms having the frequencies $\text{Ω}{}_1\text{, Ω}{}_2$ and $\text{Ω}{}_2\text{+ Ω}{}_1$ at first order and terms having the frequencies 0, $\text{2Ω}{}_1\text{, 2Ω}{}_2\text{, Ω}{}_2\text{? Ω}{}_1$, $\text{2(Ω}{}_2\text{+ Ω}{}_1\text{), Ω}{}_2\text{+ 2Ω}{}_1$ and $\text{2Ω}{}_2\text{+ Ω}{}_1$ at second order. Second, it produces a shift in the natural frequency of the system. Third, it produces a virtual primary-resonant excitation having the frequency $\text{Ω}{}_2\text{+ Ω}{}_1\text{≈ ω}{}_0$ that makes the component having the frequency $\text{Ω}{}_2\text{+ Ω}{}_1$ be of first rather than second order. Similar effects are produced by a combination resonance of the difference type or a superharmonic resonance of order two.     

An effective procedure to determine corrugation functions from atomic beam-diffraction intensities

A computational method is described, which, starting from given difraction intensities, approaches effectively the best-fit corrugation function $\text{ζ(}\text{R}\text{)}$. Because of the approximations involved, the procedure works well for smooth corrugations with amplitudes not exceeding ～10% of the lattice constant. The method rests on two crucial observations: (i) With the full knowledge of the scattering amplitudes $\text{A}{}_{\mathrm{G}}\text{= ¦A}{}_{\mathrm{G}}\text{¦}\text{exp}\text{(}\text{i}\text{?}{}_{\mathrm{G}}\text{)}$ (absolute values plus phases), the corrugation function can be calculated to a high degree of accuracy from $\text{ζ(}\text{R}\text{) = (2}\text{i}\text{k}{}_{\mathrm{i}}\text{)}{}^{\mathrm{?1}}$ In $\text{¦?ΣA}{}_{\mathrm{G}}\text{exp}\text{(}\text{i}\text{G·R}\text{)¦}$ which is derived easily from the hard corrugated wall scattering (HCWS) equation by approximating $\text{k}{}_{\mathrm{G}}$ by $\text{?}\text{k}{}_{\mathrm{i}}$ ($\text{k}{}_{\mathrm{i}}$ and $\text{k}{}_{\mathrm{G}}$ being the wavevectors of the incoming and diffracted beams, respectively), (ii) With only the $\text{¦A}{}_{\mathrm{G}}\text{¦'s}$ (or intensities) known, approximate solutions of the HCWS equation can be obtained with a rough estimate of the relative phases of only a few intense diffraction beams; the estimate is readily performed by investigating systematically a coarse mesh of phases. In this way, approximate corrugations are found with which a full set of phases can be generated, which allows the calculation of an improved ζ(R); this step is repeated in a loop, until optimum agreement between calculated and given intensities is obtained. The effectiveness of the procedure is demonstrated for three one-dimensional model corrugations described by several Fourier coefficients. The method is finally applied to the case of H₂ diffraction from the quasi-one-dimensional adsorbate corrugation Ni(110) + H(1 × 2).     

Elastic anharmonicity of InP: Its relationship to the high pressure transition

Ultrasonic wave transit times have been measured in n-type InP at room temperature using hydrostatic pressures up to 4 kbar. Linear pressure dependences are found for the elastic stiffness moduli implying that at the high pressure structural-electrical transition the shear-to-bulk modulus ratio $\text{(C}{}_{11}\text{?C}{}_{12}\text{)}\text{2B}$ has a (fractional) value which fits the modified Born criterion for stability developed by Demarest $\text{et al}$. The anharmonic force constants and some of the third order elastic constants are found to be smaller the higher the transition pressure for indium III-V compounds.     

An optical scale model of traffic noise propagation in an urban environment

This paper describes principles of modelling traffic noise using an optical scale model. The main difference between this model and the widely used ‘acoustical’ scale model is that it makes use of light instead of sound. There were four phases to the study. The first of these involved the propagation of single vehicle noise over ground and its dependence upon distance and vehicle velocity. The second phase was concerned with light emitted by a small lamp, which imitated a single vehicle. The third part of the work dealt with the principles of the optical model, its construction and use in predicting the equivalent level, $\text{L}{}_{\mathrm{<mtext>eq</mtext>}}$, of traffic noise. Finally, a model of a part of a residential area of Poznań, Poland, was built and values of $\text{L}{}_{\mathrm{<mtext>eq</mtext>}}$ computed. These results were compared with field measurements.     

On the sound absorption in ferrodielectrics

The damping of the sound waves in ferromagnets due to the phonon-magnon interaction is considered for the temperature $\text{θ}{}_{\mathrm{c}}\text{(}\text{μM}{}_0\text{4}\text{7θ}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}\text{? T ?}\text{θ}{}^2{}_{\mathrm{D}}\text{4}\text{7θ}{}_{\mathrm{c}}$ and frequency τ^?1_m-ph ? ω ? τ^?1_m ranges. This damping is found to be greater than the Landau-Rumer one due to the anharmonic interactions in the crystal. The Akhiezer's method for the calculation of the sound damping is shown to be valid for the more wide frequency range than it was regarded earlier.     

Computer simulation of collective phenomena in a turbulent plasma

A short review of the results of one- and two-dimensional computer investigations of strong Langmuir turbulence is given. The main topics of interest are the following: formation of high energetic electron tails; ion sound turbulence accompanying collapse and plasmons' conversion; modulation instability (MI) in X,Y-geometry for $\text{T}{}_{\mathrm{e}}\text{T}{}_{\mathrm{i}}\text{? 1}$ and $\text{T}{}_{\mathrm{e}}\text{T}{}_{\mathrm{i}}\text{?1}$; MI in transverse magnetic field. The case of the “forced” collapse (quasicollapse) in presence of an external pump $\text{E}{}_{\mathrm{<mtext>ext</mtext>}}\text{=}\text{E}{}_{\mathrm{<mtext>ox</mtext>}}\text{Cos}\text{ω}{}_{\mathrm{o}}\text{t}$ is considered.     

Traffic noise annoyance near light controlled intersections

Four hundred noise samples were taken at varying distances from three light-controlled intersections, from which the increments in percentile level above those predicted for the equivalent free flow case were derived. No factors other than those included in the prediction method could be discerned, and linear regression of the whole sample was used to establish the relationship between the increment, $\text{ΔL}{}_{\mathrm{<mtext>n</mtext>}}$, and distance, $\text{x}\text{(m)}$, from the intersection, e.g. $\text{ΔL}{}_{10}\text{= 3·21 ? 0·01}\text{x}$. A postal social survey with 12 environmental questions was sent to 30 subjects at each of six free and six interrupted flow sites, where 18-h noise measurements were made. A 69 per cent response was obtained. The slope of the regression line between question scores and $\text{L}{}_{\mathrm{<mtext>10</mtext>}}$ was found to differ between free and interrupted flow, but those against $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$ were similar. The ‘dissatisfaction’ score and a composite ’annoyance’ score correlated well, 0·76, but ‘dissatisfaction’ gave a slightly higher score for free flow than interrupted, and ‘annoyance’ the reverse. This suggests that $\text{L}{}_{\mathrm{<mtext>50</mtext>}}$ is a useful indicator of subjective response if both free and interrupted flows are involved. However the data also supports the use of the logarithm of percentage of heavy vehicles as an indicator of dissatisfaction in the interrupted flow case.