Measurement and prediction of typical speech and background-noise levels in university classrooms during lectures

This study investigated the acoustical quality of seven classrooms and learning spaces at King Abdulaziz University in Jeddah. The physical characteristics of sounds measured in these classrooms included Background Noise Levels (BNLs - dBA) and Reverberation Times (RTs - seconds). Measurements were conducted in unoccupied conditions. In addition, information about rooms' sizes, design, components and building materials were collected. Results of BNLs and RTs indicated poor acoustical condition in the new classrooms, while old classrooms provided fair or acceptable acoustical quality for learning and teaching based on their RTs. BNLs in the new classrooms ranged from 42 to 71 dBA, and RTs ranged from 1 to 1.4 seconds, which all were higher than the allowable BNL (35 dBA) and RT (0.6 seconds) (ANSI 12.60.2010) according to their rooms sizes. This poor acoustical condition were found to be associated with ventilation noise, reflective surfaces, and classroom design. In conclusion, recommendations to improve the acoustical quality for better learning and teaching in the investigated new classrooms were highlighted in this paper.

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The Canterbury Child's Aid: A Binaural Spatial Sensor for Research with Blind Children

Journal of Visual Impairment & Blindness ◽

10.1177/0145482x7907300503 ◽

1979 ◽

Vol 73 (5) ◽

pp. 179-184

Author(s):

E. R. Strelow ◽

J. T. Boys

Keyword(s):

Future Development ◽

Background Noise ◽

Field Of View ◽

Basic Operation ◽

Noise Levels ◽

Design Features ◽

Blind Children ◽

Automatic Level

A binaural sensory aid for research with blind children is described along with the rationale for its design features. The basic operation of this form of aid is described in detail with particular reference to those features that control the sensing parameters of range, direction and field of view. A novel automatic level controller which ensures that device sounds remain audible but not excessively loud, in spite of changes in background noise levels, is also described. The likely future development of these forms of sonic aids is discussed.

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Background noise analysis in urban airport surroundings of Brazilian cities, Congonhas Airport, São Paulo

Revista de Saúde Pública ◽

10.1590/s1518-8787.2016050006431 ◽

2016 ◽

Vol 50 (0) ◽

Author(s):

Fabio Scatolini ◽

Cláudio Jorge Pinto Alves

Keyword(s):

Traffic Control ◽

Background Noise ◽

Noise Analysis ◽

Exposure Level ◽

Noise Levels ◽

Sound Exposure ◽

Operational Characteristics ◽

Data Compilation ◽

Noise Measurements ◽

Noise Data

ABSTRACT OBJECTIVE To perform a quantitative analysis of the background noise at Congonhas Airport surroundings based on large sampling and measurements with no interruption. METHODS Measuring sites were chosen from 62 and 72 DNL (day-night-level) noise contours, in urban sites compatible with residential use. Fifteen sites were monitored for at least 168 hours without interruption or seven consecutive days. Data compilation was based on cross-reference between noise measurements and air traffic control records, and results were validated by airport meteorological reports. Preliminary diagnoses were established using the standard NBR-13368. Background noise values were calculated based on the Sound Exposure Level (SEL). Statistic parameters were calculated in one-hour intervals. RESULTS Only four of the fifteen sites assessed presented aircraft operations as a clear cause for the noise annoyance. Even so, it is possible to detect background noise levels above regulation limits during periods of low airport activity or when it closes at night. CONCLUSIONS All the sites monitored showed background noise levels above regulation limits between 7:00 and 21:00. In the intervals between 6:00-6:59 and 21:00-22:59 the noise data, when analyzed with the current airport operational characteristics, still allow the development of additional mitigating measures.

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Background‐Noise Levels in Suburban Communities

The Journal of the Acoustical Society of America ◽

10.1121/1.2142388 ◽

1963 ◽

Vol 35 (5) ◽

pp. 779-780 ◽

Cited By ~ 1

Author(s):

Lewis S. Goodfriend ◽

R. L. Cardinell ◽

Paul B. Ostergaard ◽

Ray Donley

Keyword(s):

Background Noise ◽

Noise Levels ◽

Suburban Communities

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Mapping speech transmission index (STI) and background noise in university classrooms

The Journal of the Acoustical Society of America ◽

10.1121/1.4987247 ◽

2017 ◽

Vol 141 (5) ◽

pp. 3481-3481

Author(s):

Andrew Hulva ◽

Michael Ermann ◽

Jeffrey Rynes ◽

Randall J. Rehfuss ◽

Aaron Kanapesky ◽

...

Keyword(s):

Background Noise ◽

Transmission Index ◽

Speech Transmission ◽

University Classrooms

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Sparsified nightly fish chorusing in the Dry Tortugas during elevated background noise levels due to a tropical storm

The Journal of the Acoustical Society of America ◽

10.1121/1.4988942 ◽

2017 ◽

Vol 141 (5) ◽

pp. 3944-3944

Author(s):

Benjamin S. Gottesman ◽

Dante Francomano ◽

Taylor Broadhead ◽

Bryan C. Pijanowski

Keyword(s):

Background Noise ◽

Tropical Storm ◽

Noise Levels ◽

Dry Tortugas

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Auditory and Visual Effects on Solutions to Computerized Mathematics Problems as a Function of Rate of Digit Presentation ,

Perceptual and Motor Skills ◽

10.1177/00315125890693-212 ◽

1989 ◽

Vol 69 (3-2) ◽

pp. 1127-1130 ◽

Cited By ~ 5

Author(s):

William F. Vitulli ◽

Connie P. Anderson

Keyword(s):

Background Noise ◽

Sound Pressure ◽

Paired Comparison ◽

Noise Levels ◽

Visual Effects ◽

Mathematics Problems ◽

Exploratory Investigation ◽

Significant Difference ◽

Masking Noise ◽

Post Hoc

This exploratory investigation concerned the effects of both auditory and visual stimulus variations on the accuracy of mental solutions to addition problems presented on a computer screen (CRT). 5 intensities of background noise and 5 background hues were presented randomly to 123 undergraduate volunteers as they mentally summed 25 numerals ranging from 1 to 5 at rates of either 1 sec. or 3 sec. per numeral timed from the onset of the previous numeral. A 2 × 2 × 5 mixed split-plot factorial analysis of variance gave a significant difference in errors between rates of digit presentation with greater accuracy associated with the 3-sec. rate. There was no significant difference in mean errors for auditory vs color modalities, yet a post hoc Newman-Keuls paired-comparison test of decibel levels at the 1-sec. rate of digit presentation gave a significant difference in mean errors between 60-dB and 70-dB sound-pressure levels (SPLs) of white masking noise. Also, a post hoc F test on differences between successive stages indicated significant differences suggesting a “learning set.” Comparisons between ‘everyday’ instances of these noise levels are made with implications for optimal computational environments.

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Auditory nerve representation of vowels in background noise

Journal of Neurophysiology ◽

10.1152/jn.1983.50.1.27 ◽

1983 ◽

Vol 50 (1) ◽

pp. 27-45 ◽

Cited By ~ 77

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.

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