An investigation has been carried out to examine the impact of different levels of classroom noise on adolescents' performance on reading and vocabulary-learning tasks. A total of 976 English high school pupils (564 aged 11 to 13 years and 412 aged 14 to 16 years) completed reading tasks on laptop computers while exposed to different levels of classroom noise played through headphones. The tasks consisted of reading science texts, which were followed by multiple-choice questions probing comprehension and word learning. Number of questions attempted, times taken to read the texts and to answer questions were recorded, as well as correct answers to different types of question. The study consisted of two similar experiments, the first comparing performance in classroom noise at levels of 50 and 70 dB LAeq; and the second at levels of 50 and 64 dB LAeq. The results showed that the performance of all pupils was significantly negatively affected in the 70 dB LAeq condition, for the number of questions attempted and the accuracy of answers to factual and word learning questions. It was harder to discern effects at 64 dB LAeq, this level of noise having a detrimental effect upon the older pupils only.

An acoustic survey of secondary schools in England has been undertaken. Room acoustic parameters and background noise levels were measured in 185 unoccupied spaces in 13 schools to provide information on the typical acoustic environment of secondary schools. The unoccupied acoustic and noise data were correlated with various physical characteristics of the spaces. Room height and the amount of glazing were related to the unoccupied reverberation time and therefore need to be controlled to reduce reverberation to suitable levels for teaching and learning. Further analysis of the unoccupied data showed that the introduction of legislation relating to school acoustics in England and Wales in 2003 approximately doubled the number of school spaces complying with current standards. Noise levels were also measured during 274 lessons to examine typical levels generated during teaching activities in secondary schools and to investigate the influence of acoustic design on working noise levels in the classroom. Comparison of unoccupied and occupied data showed that unoccupied acoustic conditions affect the noise levels occurring during lessons. They were also related to the time spent in disruption to the lessons (e.g., students talking or shouting) and so may also have an impact upon student behavior in the classroom.

Spatial audio processes (SAPs) commonly encountered in consumer audio reproduction systems are known to generate a range of impairments to spatial quality. Two listening tests (involving two listening positions, six 5-channel audio recordings, and 48 SAPs) indicate that the degree of quality degradation is determined largely by the nature of the SAP but that the effect of a particular SAP can depend on program material and on listening position. Combining off-center listening with another SAP can reduce spatial quality significantly compared to auditioning that SAP centrally. These findings, and the associated listening test data, can guide the development of an artificial-listener-based spatial audio quality evaluation system.

Previously-obtained data, quantifying the degree of quality degradation resulting from a range of spatial audio processes (SAPs), can be used to build a regression model of perceived spatial audio quality in terms of previously developed spatially and timbrally relevant metrics. A generalizable model thus built, employing just five metrics and two principal components, performs well in its prediction of the quality of a range of program types degraded by a multitude of SAPs commonly encountered in consumer audio reproduction, auditioned at both central and off-center listening positions. Such a model can provide a correlation to listening test data of r = 0.89, with a root mean square error (RMSE) of 11%, making its performance comparable to that of previous audio quality models and making it a suitable core for an artificial-listener-based spatial audio quality evaluation system.

Since 2003 new school buildings in England and Wales have been subject to Building Regulations which impose a legal requirement for spaces in schools to meet acoustic performance criteria for ambient noise levels, reverberation times and sound insulation. The criteria are specified in the Department of Education publication ‘Building Bulletin 93’ (BB93). In 2008 it was agreed that BB93 would be updated. The Labour government endorsed the need for good acoustic design of schools and agreed to a minor revision of the legislation. However, the new government elected in 2010 recommended the removal of legislation on school acoustics, in order to reduce the cost of new school buildings. The acoustics community in the UK successfully lobbied the government to keep the legislation and it has been agreed that the acoustic regulations relating to the performance of a building in use will be retained. BB93 is currently (June 2012) being redrafted and the acoustic performance specifications revised. This paper will use the results of a recent large scale survey of the acoustics of secondary schools in the UK to examine the impact of BB93 on school design over the past 10 years, and will discuss the current revision of the legislation.

This paper investigates blind Reverberation Time (RT) estimation in occupied classrooms and hospital wards. Measurements are usually made while these spaces are unoccupied for logistical reasons. However, occupancy can have a significant impact on the rate of reverberant decay. Recent work has developed a Maximum Likelihood Estimation (MLE) method which utilises only passively recorded speech and music signals, this enables measurements to be made while the room is in use. In this paper the MLE method is applied to recordings made in classrooms during lessons. Classroom occupancy levels differ for each lesson, therefore a model is developed using blind estimates to predict the RT for any occupancy level to within +/-0.07 s for the mid-frequency octave bands. The model is also able to predict the effective room and per person absorption area.Ambient sound recordings were also carried out in a number of rooms in two hospitals for a week. Hospital measurements are more challenging as the occurrence of free reverberant decay is rarer than in schools and the acoustic conditions may be non-stationary. However, by gaining recordings over a period of a week, estimates can be gained within +/-0.07 s. These estimates are representative of the times when the room contains the highest acoustic absorption. In other words when curtains are drawn, there are many visitors or perhaps a window may be open. (C) 2012 Elsevier Ltd. All rights reserved.

A recent project has investigated acoustical conditions in secondary (high) schools, and examined the effects of a poor acoustic environment on teaching and learning of 11- to 16-year-olds. Around 2600 pupils from suburban secondary schools in England responded to an online questionnaire concerning the acoustic environment in their schools. The questionnaire data highlighted the differential effects of noise reported by more vulnerable learners. A repeated measures experimental study involving 572 pupils examined reading performance under two different classroom noise simulations. Results revealed a complex pattern reflecting noise levels, time of testing and measure of reading performance used. Reading text while exposed to classroom noise of 70 dB resulted in quicker reading but less accuracy in measures of reading comprehension compared with performance in 50 dB. The data further suggested that the pupils were not processing the text as deeply as was evident from their reduced lexical learning. There were also interactions with time of testing highlighting the importance of examining the effects of chronic exposure in addition to single session experimental testing. The test results show that capturing the effects of noise on pupils’ learning in realistic classroom environments raises a number of methodological and analytical problems.

An objective prediction model for the sensation of sound envelopment in five-channel reproduction is important for evaluating spatial quality. Regression analysis was used to map the listening test scores on a variety of audio sources and the objective measures extracted from the recordings themselves. By following an iterative process, a prediction model with five features was constructed. The validity of the model was tested in a second set of subjective scores and showed a correlation coefficient of 0.9. Among the five features: sound distribution and interaural cross-correlation contributed substantially to the sensation of envelopment. The model did not require access to the original audio. Scales used for listening tests were defined by audible anchors.

This paper describes a computational model for the prediction of perceived spatial quality for reproduced sound at arbitrary locations in the listening area. The model is specifically designed to evaluate distortions in the spatial domain such as changes in source location, width and envelopment. Maps of perceived spatial quality across the listening area are presented from our initial results.

The spatial quality of audio content delivery systems is becoming increasingly important as service providers attempt to deliver enhanced experiences of spatial immersion and naturalness in audio-visual applications. Examples are virtual reality, telepresence, home cinema, games and communications products. The QESTRAL project is developing an artificial listener that will compare the perceived quality of a spatial audio reproduction to a reference reproduction. The model is calibrated using data from listening tests, and utilises a range of metrics to predict the resulting spatial sound quality ratings. Potential application areas for the model are outlined, together with exemplary results obtained from some of its component parts.

This paper describes the development of an unintrusive objective model, developed independently as a part of the QESTRAL project, for predicting the sensation of envelopment arising from commercially available 5-channel surround sound recordings. The model was calibrated using subjective scores obtained from listening tests that used a grading scale defined by audible anchors. For predicting subjective scores, a number of features based on Interaural Cross Correlation (IACC), Karhunen-Loeve Transform (KLT) and signal energy levels were extracted from recordings. The ridge regression technique was used to build the objective model and a calibrated model was validated using a listening test scores database obtained from a different group of listeners, stimuli and location. The initial results showed a high correlation between predicted and actual scores obtained from the listening tests.

Most current perceptual models for audio quality have so far tended to concentrate on the audibility of distortions and noises that mainly affect the timbre of reproduced sound. The QESTRAL model, however, is specifically designed to take account of distortions in the spatial domain such as changes in source location, width and envelopment. It is not aimed only at codec quality evaluation but at a wider range of spatial distortions that can arise in audio processing and reproduction systems. The model has been calibrated against a large database of listening tests designed to evaluate typical audio processes, comparing spatially degraded multichannel audio material against a reference. Using a range of relevant metrics and a sophisticated multivariate regression model, results are obtained that closely match those obtained in listening tests.

The QESTRAL project aims to develop an artificial listener for comparing the perceived quality of a spatial audio reproduction against a reference reproduction. This paper presents implementation details for simulating the acoustics of the listening environment and the listener’s auditory processing. Acoustical modeling is used to calculate binaural signals and simulated microphone signals at the listening position, from which a number of metrics corresponding to different perceived spatial aspects of the reproduced sound field are calculated. These metrics are designed to describe attributes associated with location, width and envelopment attributes of a spatial sound scene. Each provides a measure of the perceived spatial quality of the impaired reproduction compared to the reference reproduction. As validation, individual metrics from listening test signals are shown to match closely subjective results obtained, and can be used to predict spatial quality for arbitrary signals.

The QESTRAL model is a perceptual model that aims to predict changes to spatial quality of service between a reference system and an impaired version of the reference system. To achieve this, the model required calibration using perceptual data from human listeners. This paper describes the development, implementation and outcomes of a series of listening experiments designed to investigate the spatial quality impairment of 40 processes. Assessments were made using a multi-stimulus test paradigm with a label-free scale, where only the scale polarity is indicated. The tests were performed at two listening positions, using experienced listeners. Results from these calibration experiments are presented. A preliminary study on the process of selecting of stimuli is also discussed.

The QESTRAL project has developed an artificial listener that compares the perceived quality of a spatial audio reproduction to a reference reproduction. Test signals designed to identify distortions in both the foreground and background audio streams are created for both the reference and the impaired reproduction systems. Metrics are calculated from these test signals and are then combined using a regression model to give a measure of the overall perceived spatial quality of the impaired reproduction compared to the reference reproduction. The results of the model are shown to match closely the results obtained in listening tests. Consequently, the model can be used as an alternative to listening tests when evaluating the perceived spatial quality of a given reproduction system, thus saving time and expense.