Speech and noise levels in classrooms—signal, noise, reverberation levels as a metric for acoustic design for learning

2006 ◽  
Vol 120 (5) ◽  
pp. 3200-3201
Author(s):  
Line Guerra ◽  
Nicolas Teichner ◽  
Sooch San Souci ◽  
Dick Campbell
Keyword(s):  
Noise Levels ◽  
Signal Noise ◽  
Acoustic Design ◽  
Design For Learning

Auditory nerve representation of vowels in background noise

1983 ◽  
Vol 50 (1) ◽  
pp. 27-45 ◽  
Author(s):  
M. B. Sachs ◽  
H. F. Voigt ◽  
E. D. Young
Keyword(s):  
Steady State ◽  
Auditory Nerve ◽  
Background Noise ◽  
Discharge Rate ◽  
Nerve Fibers ◽  
Noise Levels ◽  
Stimulus Component ◽  
Signal Noise ◽  
Formant Frequencies ◽  
Second Formant

Responses of auditory nerve fibers to steady-state vowels presented alone and in the presence of background noise were obtained from anesthetized cats. Representation of vowels based on average discharge rate and representation based primarily on phase-locked properties of responses are considered. Profiles of average discharge rate versus characteristic frequency (CF) ("rate-place" representation) can show peaks of discharge rate in the vicinity of formant frequencies when vowels are presented alone. These profiles change drastically in the presence of background noise, however. At moderate vowel and noise levels and signal/noise ratios of +9 dB, there are not peaks of rate near the second and third formant frequencies. In fact, because of two-tone suppression, rate to vowels plus noise is less than rate to noise alone for fibers with CFs above the first formant. Rate profiles measured over 5-ms intervals near stimulus onset show clear formant-related peaks at higher sound levels than do profiles measured over intervals later in the stimulus (i.e., in the steady state). However, in background noise, rate profiles at onset are similar to those in the steady state. Specifically, for fibers with CFs above the first formant, response rates to the noise are suppressed by the addition of the vowel at both vowel onset and steady state. When rate profiles are plotted for low spontaneous rate fibers, formant-related peaks appear at stimulus levels higher than those at which peaks disappear for high spontaneous fibers. In the presence of background noise, however, the low spontaneous fibers do not preserve formant peaks better than do the high spontaneous fibers. In fact, the suppression of noise-evoked rate mentioned above is greater for the low spontaneous fibers than for high. Representations that reflect phase-locked properties as well as discharge rate ("temporal-place" representations) are much less affected by background noise. We have used synchronized discharge rate averaged over fibers with CFs near (+/- 0.25 octave) a stimulus component as a measure of the population temporal response to that component. Plots of this average localized synchronized rate (ALSR) versus frequency show clear first and second formant peaks at all vowel and noise levels used. Except at the highest level (vowel at 85 dB sound pressure level (SPL), signal/noise = +9 dB), there is also a clear third formant peak. At signal-to-noise ratios where there are no second formant peaks in rate profiles, human observers are able to discriminate second formant shifts of less than 112 Hz. ALSR plots show clear second formant peaks at these signal/noise ratios.

The Significance of Balcony Acoustic Treatments in Mitigating Urban Road Traffic Noise

2012 ◽  
Author(s):  
Andy C. C. Tan ◽  
Daniel A. Naish ◽  
F. Nur Demirbilek
Keyword(s):  
Road Traffic ◽  
Traffic Noise ◽  
Internal Noise ◽  
Road Traffic Noise ◽  
Noise Levels ◽  
Acoustic Design ◽  
Urban Road ◽  
Technological Advances ◽  
Modern Cities ◽  
Building Facades

Urban road traffic noise in cities is an ongoing and increasing problem across much of the world. Consequently a large amount of effort is expended in attempts to address this problem, especially in the area of acoustic design of buildings. Acoustic design policies developed by government authorities will typically focus on required transport noise reductions through a building façade to meet a specified internal noise levels. The significance of balcony acoustic treatments has been highlighted in recent decades yet this area has potentially been considered less important than the need for acoustic isolation of building facades. This paper outlines recent research that has been conducted in determining the significance of balcony acoustic treatments in mitigating urban road traffic noise. It summarizes recent literature, some of which focuses on technological advances in the knowledge of balcony acoustic design and some literature discusses the overall aims and benefits of balcony acoustic design. The aim of this paper is to promote the use of balcony acoustic design as a significant element in the overall solution towards mitigating road traffic noise in modern cities.

Rician envelope estimation and confidence intervals in low signal/noise levels

1987 ◽  
Vol 23 (16) ◽  
pp. 832 ◽  
Author(s):  
B.G. Stewart ◽  
J.F.L. Simmons
Keyword(s):  
Confidence Intervals ◽  
Noise Levels ◽  
Signal Noise

Predicting Acoustical Noise Generation in Complex Mechanical Systems

1979 ◽  
Vol 101 (2) ◽  
pp. 199-209 ◽  
Author(s):  
N. D. Perreira ◽  
S. Dubowsky
Keyword(s):  
Analytical Procedure ◽  
Mechanical Systems ◽  
Design Guidelines ◽  
Noise Generation ◽  
Noise Levels ◽  
Fundamental Study ◽  
Acoustic Design ◽  
System A ◽  
Modal Power ◽  
Complex Mechanical Systems

A fundamental study of noise generation in complex mechanical systems is undertaken. The objective of the study is the development of design guidelines for the prediction of mechanical system noise levels. Recently developed dynamical procedures are used to obtain the motions of linked mechanical systems with elastic elements and connection clearances. An analytical procedure for modeling the acoustical noise generated by complex mechanical systems is applied to a typical linked system, a four-bar mechanism. The far field acoustic pressure distribution is calculated and shown to be a function of many of the parameters under the control of the system designer. To aid the designer in producing quieter systems, acoustic design functions are developed. In particular, the system sound power and modal power efficiencies are found to be promising design tools.

Case Study: Acoustic Design of a Restored Theatre in Thessaloniki

2000 ◽  
Vol 7 (2) ◽  
pp. 137-150
Author(s):  
N. P. Tsinikas
Keyword(s):  
Background Noise ◽  
Lateral Wall ◽  
Reverberation Time ◽  
Noise Levels ◽  
Acoustic Design ◽  
Design Changes ◽  
Wire Frame ◽  
Measurement Results ◽  
Side Walls

This paper discusses the acoustics of a restored theatre in Thessaloniki, Greece. The paper presents the acoustic design principles, discusses the employment of these principles and concludes with an assessment of the success of the design. The acoustic design changes included improvement of direct sound, provision of ceiling and walls reflections, positioning of diffusers, optimising reverberation time and minimising background noise levels. Steeper seating rakes were constructed in the stalls, boxes and balconies. Curved ceiling reflectors were positioned in a new wire frame false ceiling. Lateral wall reflectors were introduced, as were curved side walls near the stage to act as diffusers. Diffusers were positioned in the rear walls and in balcony fronts. Reverberation times were predicted, measured and compared with earlier data, based on the change of volume, the number and design of seats and the volume per seat ratio. Finally, noise level measurements were obtained in most of the spaces in the theatre. Assessment of the success of the design is based on measurement results and on the subjective acceptance by theatre goers.

Information in Spectra of Collision-Broadened Absorption Lines

1979 ◽  
Vol 33 (6) ◽  
pp. 569-574 ◽  
Author(s):  
E. Niple ◽  
J. H. Shaw
Keyword(s):  
Absorption Lines ◽  
Line Center ◽  
Line Position ◽  
Noise Levels ◽  
Unknown Parameters ◽  
Experimental Conditions ◽  
Trade Off ◽  
Signal Noise ◽  
Nonlinear Design ◽  
Noise Ratio

A mathematical model is introduced for experiments which yield spectra of isolated, collision-broadened absorption lines. A nonlinear design analysis is then performed on the model to identify the optimum experimental conditions. The information in the spectra is split into components associated with each of the unknown parameters to be estimated from the spectra. By exploring the variation of these components it is shown that spectra with line center transmittances of 0.25 are nearly optimum for measuring the line position, the Lorentz width α, the instrument resolution H, and the product of line intensity and absorber amount. The trade off between signal/noise ratio and resolution is investigated for several different resolution-dependent noise levels. The analysis shows that when signal/noise ratio is proportional to the square root of the ratio of resolution and Lorentz width, a single optimum resolution and line center transmittance combination of H/α ≅ 1.5 and 0.28, respectively, exists.

Signal/Noise Ratio and Elemental Detectivity by Eels

1982 ◽  
Vol 40 ◽  
pp. 488-489
Author(s):  
R. F. Egerton
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Elemental Analysis ◽  
Electron Energy Loss Spectroscopy ◽  
Emission Spectroscopy ◽  
X Ray ◽  
Signal Noise ◽  
Characteristic Signal ◽  
Noise Ratio ◽  
Electron Energy Loss

An important parameter governing the sensitivity and accuracy of elemental analysis by electron energy-loss spectroscopy (EELS) or by X-ray emission spectroscopy is the signal/noise ratio of the characteristic signal.

Damage Risk: An Evaluation of the Effects of Exposure to 85 versus 90 dBA of Noise

1976 ◽  
Vol 19 (2) ◽  
pp. 216-224 ◽  
Author(s):  
James T. Yates ◽  
Jerry D. Ramsey ◽  
Jay W. Holland
Keyword(s):  
White Noise ◽  
Statistical Difference ◽  
Noise Exposure ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Noise Levels ◽  
Potential Damage ◽  
Full Day ◽  
Damage Risk

The purpose of this study was to compare the damage risk of 85 and 90 dBA of white noise for equivalent full-day exposures. The damage risk of the two noise levels was determined by comparing the temporary threshold shift (TTS) of 12 subjects exposed to either 85 or 90 dBA of white noise for equivalent half- and full-day exposures. TTS was determined by comparing the pre- and postexposure binaural audiograms of each subject at 1, 2, 3, 4, 6, and 8 kHz. It was concluded that the potential damage risk, that is, hazardous effect, of 90 dBA is greater than 85 dBA of noise for equivalent full-day exposures. The statistical difference between the overall effects of equivalent exposures to 85 dBA as compared to 90 dBA of noise could not be traced to any one frequency. The damage risk of a full-day exposure to 85 dBA is equivalent to that of a half-day exposure to 90 dBA of noise. Within the limits of this study, TTS t was as effective as TTS 2 for estimating the damage risk of noise exposure.

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