scholarly journals A Study of Classroom Acoustics and Its Effects of Listeners’ Locations on Speech Intelligibility

1970 ◽  
Vol 7 (1) ◽  
pp. 64-71
Author(s):  
Chukiet Sodsri
Keyword(s):  
Linear Systems ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Noise Source ◽  
Reverberation Time ◽  
Impulse Responses ◽  
Acoustical Parameters ◽  
Classroom Acoustics ◽  
Common Process ◽  
Speech Clarity

Attending a class and listening to a lecture given by an instructor is a common process in Thailand education. Ability of learning is affected by the ability of hearing the instructors’ speech. Acoustical environments of the classroom, hence, can influence speech intelligibility. In this research, acoustical parameters and listeners’ locations in classrooms and their effects on the speech intelligibility were studied. By using an assumption of linear systems of the classrooms, the room reverberation, background noise, and other classroom acoustical factors can be implicated as impulse responses of the system. Maximum length sequence was used to identify the impulse responses at listeners’ locations in the classrooms. A clean speech, recorded in a semi-anechoic room, was convoluted with a series of the measured classrooms’ impulse responses to yield a set of simulated reverberant speeches that the listener at each location in the classes would have heard. A number of volunteers were invited to test an ability of understanding the speech. The experimental results showed that the reverberation and background noise at listeners’ locations severely affected the speech intelligibility. A classroom, that seemed to have a good averaged reverberation time, did not always yielded good speech clarity for all the locations in the class. In fact, for the classroom used in the study, the rear section of the class was poor for intelligibility and the back corner closed to a noise source was the worse location for speech hearing.

Challenging listening environments in higher education: an analysis of academic classroom acoustics

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kirsten van den Heuij ◽  
Theo Goverts ◽  
Karin Neijenhuis ◽  
Martine Coene
Keyword(s):  
Higher Education ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Academic Language ◽  
Acoustic Properties ◽  
Reference Level ◽  
Teaching Staff ◽  
Reference Levels ◽  
Classroom Acoustics ◽  
Content Type

PurposeAs oral communication in higher education is vital, good classroom acoustics is needed to pass the verbal message to university students. Non-auditory factors such as academic language, a non-native educational context and a diversity of acoustic settings in different types of classrooms affect speech understanding and performance of students. The purpose of this study is to find out whether the acoustic properties of the higher educational teaching contexts meet the recommended reference levels.Design/methodology/approachBackground noise levels and the Speech Transmission Index (STI) were assessed in 45 unoccupied university classrooms (15 lecture halls, 16 regular classrooms and 14 skills laboratories).FindingsThe findings of this study indicate that 41 classrooms surpassed the maximum reference level for background noise of 35 dB(A) and 17 exceeded the reference level of 40 dB(A). At five-meter distance facing the speaker, six classrooms indicated excellent speech intelligibility, while at more representative listening positions, none of the classrooms indicated excellent speech intelligibility. As the acoustic characteristics in a majority of the classrooms exceeded the available reference levels, speech intelligibility was likely to be insufficient.Originality/valueThis study seeks to assess the acoustics in academic classrooms against the available acoustic reference levels. Non-acoustic factors, such as academic language complexity and (non-)nativeness of the students and teaching staff, put higher cognitive demands upon listeners in higher education and need to be taken into account when using them in daily practice for regular students and students with language/hearing disabilities in particular.

Poor Listening Conditions Impair Memory for Intelligible Lectures: Implications for Acoustic Classroom Standards

2009 ◽  
Vol 16 (3) ◽  
pp. 257-265 ◽  
Author(s):  
Robert Ljung ◽  
Patrik Sörqvist ◽  
Anders Kjellberg ◽  
Anne-Marie Green
Keyword(s):  
University Students ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Broadband Noise ◽  
Speech Signals ◽  
Reverberation Time ◽  
Signal To Noise ◽  
Memory And Learning ◽  
What Is Said ◽  
Degraded Speech

This paper reports two experiments on the effects of degraded speech signals on memory for spoken lectures. Experiment 1 showed that broadband noise impairs university students' memory for a spoken lecture, even though the participants heard what was said. Experiment 2 showed that reverberation has detrimental effects to school adolescents' memory for spoken lectures, similar to broadband noise. The results suggest that poor listening conditions (resulting from background noise and/or long reverberation time) impair memory and learning, even if the conditions allow the listeners to hear what is said. Since the goal for students and pupils attending to lectures is to remember the lecture rather than just hearing what is said, the results presented here indicate that standards for acceptable signal-to-noise ratios and reverberation times in buildings designed for learning should consider the distinction between speech intelligibility and memory. Standards should be based on memory criteria instead of intelligibility criteria.

scholarly journals Aspects regarding the acoustics of a lecture hall

2019 ◽  
Vol XXII (2) ◽  
pp. 268-275
Author(s):  
Pazara T.
Keyword(s):  
Speech Intelligibility ◽  
Great Influence ◽  
Lecture Hall ◽  
Naval Academy ◽  
Reverberation Time ◽  
Acoustical Parameters ◽  
Transmission Index ◽  
Speech Transmission ◽  
Virtual Simulations ◽  
Teaching Conditions

In a lecture hall it is vital to assure proper teaching conditions meaning that the information from the speaker/teacher must be received correctly by the listeners. Speech intelligibility is the main objective when a lecture hall is evaluated. In this paper, the authors discuss the importance of the acoustics of a lecture hall and the influence of various parameters over speech transmission from the speaker – the professors to the listeners – the students. The number of acoustical parameters is very large, but Speech Transmission Index (STI) and Reverberation Time (RT) are commonly used to evaluate the acoustics of a teaching room. Other parameters like room geometry and seat placement have great influence in speech intelligibility. As an example, a lecture hall of 120 seats from Naval Academy „Mircea cel Batran“ is investigated using virtual simulations with ODEON software. The results of the simulations are discussed and some remarks are made regarding the current condition of the lecture hall.

scholarly journals Acoustic quality assessment in a classroom through simulations and measurements

2021 ◽  
Vol 9 (72) ◽  
Author(s):  
Eriberto Oliveira do Nascimento ◽  
Paulo Henrique Trombetta Zannin
Keyword(s):  
Background Noise ◽  
Speech Intelligibility ◽  
Reverberation Time ◽  
Vocal Health ◽  
Quality Requirements ◽  
Transmission Index ◽  
Speech Transmission ◽  
Acoustic Quality ◽  
Acoustic Comfort ◽  
Minimum Requirements

The acoustic quality in a classroom directly impacts the educational relationship between the student and the teacher, reducing speech intelligibility. In addition, inadequate acoustic comfort burdens the vocal health of teachers. This study evaluated a classroom at the Federal University of Paraná, Campus Centro Politécnico, to verify its acoustic quality. The measurements of the acoustics descriptors: Reverberation Time (RT), Definition (D50), Central Time (Ts), Early Decay Time (EDT) were performed according to the ISO 3382-2 standard, concerning Noise Curves (NC) and Background Noise (BGN) these were evaluated by the  NBR 10152 and S12.2 standards. The Speech Transmission Index (STI) was measured according to IEC 60268-16 and evaluated according to ISO 9921. The useful-detrimental ratio (U50) and the other descriptors were simulated in the ODEON software version 11. Thus, the results showed that the evaluated room did not meet the minimum requirements in terms of acoustic quality, for the descriptors RT, STI, Ts, D50, RF, and NC. Simultaneously, the RT and STI were also outside the limits established by the German and Finnish standards. Therefore, it is concluded that the evaluated classroom did not reach the minimum acoustic quality requirements.

Optimum Reverberation for Speech Intelligibility for Normal and Hearing-Impaired Listeners in Realistic Classrooms Using Auralization

2007 ◽  
Vol 14 (3) ◽  
pp. 163-177 ◽  
Author(s):  
Wonyoung Yang ◽  
Murray Hodgson
Keyword(s):  
Noise Level ◽  
Speech Intelligibility ◽  
Noise Source ◽  
Virtual Classroom ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Reverberation Time ◽  
Noise Sources ◽  
Virtual Classrooms ◽  
Sound Fields

The objective of this study was to use auralization techniques to investigate the optimal reverberation for speech intelligibility for normal-hearing and hearing-impaired adult listeners in classrooms with non-diffuse sound fields. This extended a previous study involving rooms with diffuse sound fields to more realistic rooms. Modified Rhyme Test (MRT) signals were auralized in six virtual classroom configurations with different reverberation times. Each classroom contained a speech source, a listener at a receiver position, and a noise source located between the talker and the listener. Two speech- and noise-source output-level differences (0 and +4 dB) were tested. Subjects performed speech-intelligibility tests in the virtual classrooms to identify the reverberation time that gave the best results in each case. For both normal and hearing-impaired listeners, the optimal reverberation time was generally non-zero, and increased with decreased speech-to-noise level difference. Hearing-impaired subjects apparently required more early energy than normal-hearing subjects. The optimal reverberation time for speech intelligibility in classrooms is not necessarily zero, as is commonly believed. The optimal value is generally non-zero, and varies with the room, the locations of the speech and noise sources and the listener, and the noise level.

Research on Improving Room Sound Field of Exhibition Building

2014 ◽  
Vol 1065-1069 ◽  
pp. 1634-1637
Author(s):  
Qian Li ◽  
Dong Sheng Liu
Keyword(s):  
Background Noise ◽  
Speech Intelligibility ◽  
Simulation Analysis ◽  
Sound Field ◽  
Reverberation Time ◽  
High Background ◽  
Exhibition Space ◽  
Commercial Activities ◽  
Broadcasting System ◽  
High Background Noise

Generally, there is a high background noise and long reverberation time and poor speech intelligibility in exhibition space due to its big crowd and often commercial promotional activities so that communication is very hard, commercial activities broadcasting system is also difficult to ensure that customers can clearly hear the propaganda content. In this paper, through measured background noise of the new exhibition center in Chengdu, we found the acoustic problem in exhibition space, then we did simulation analysis in some exhibition building and took some acoustical process to get a good sound field.

A Preliminary Investigation of the Perceived Smallest Sound Duration Change in a Room

1997 ◽  
Vol 4 (3) ◽  
pp. 197-209
Author(s):  
D.-U. Jeong ◽  
F.R. Fricke
Keyword(s):  
Noise Level ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Preliminary Investigation ◽  
Room Acoustics ◽  
Reverberation Time ◽  
Background Noise Level ◽  
Intelligibility Test ◽  
Sound Duration

The present work aims at producing a test, similar to a speech intelligibility test, which can be used to rate the acoustic quality of rooms for music. Listeners' perceptions of the duration of sounds were investigated in an attempt to find a useful indicator of the acoustics of a room for music and speech. The research design was based on a discrimination task and a 2AFC experimental procedure. Two experiments were carried out in which two acoustic variables, reverberation time and background noise level, were varied and listeners' smallest perceivable sound duration changes were measured. It was found that the listeners' duration perceptions were significantly influenced by the reverberation time and background noise level of the listening environment, and that these discrimination procedures may form the basis for room acoustics assessments.

scholarly journals The Effects of Adding Pyramidal and Convex Diffusers on Room Acoustic Parameters in a Small Non-Diffuse Room

Acoustics ◽  
2019 ◽  
Vol 1 (3) ◽  
pp. 618-643
Author(s):  
Hassan Azad ◽  
Julie Meyer ◽  
Gary Siebein ◽  
Tapio Lokki
Keyword(s):  
Statistical Analysis ◽  
Large Scale ◽  
Reverberation Time ◽  
Impulse Responses ◽  
Acoustical Parameters ◽  
Acoustic Parameters ◽  
Acoustical Properties ◽  
Measurement Results ◽  
The Difference ◽  
Rectangular Room

This paper presents an investigation of the effects of relatively large-scale pyramidal and convex-shaped diffusers on the acoustical properties of a small non-diffuse rectangular room. Room impulse responses (RIRs) were measured in various room configurations to extract the early decay time (EDT), reverberation time (T20), early-to-late arriving sound ratio (C50), and clarity (C80). The difference between the parameters measured in the empty room were chosen to be the reference, and those measured in other room configurations was calculated. Statistical analysis of the measurement results supplements the investigation to determine whether the coverage and type of diffusers contribute significantly to the variation of the acoustical parameters. The results show that adding diffusers in the room generally decreases EDT as well as T20, and increases C50 as well as C80 for both diffuser types. The statistical analysis shows that the coverage of diffusers significantly contributes to the variation of the acoustical parameters in most conditions (octave band, diffuser type). The effect of the diffuser shape is only significant for some of the conditions (at 4 kHz, the number of diffusers). The data presented demonstrate that in a small non-diffuse room the reverberation can be controlled efficiently by redirecting the sound energy towards the most absorbing surfaces.

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