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Full-Text Articles in Mechanical Engineering

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang May 2016

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang

Lily M Wang

A large number of non-native English speakers may be found in American classrooms, both as listeners and talkers. Little is known about how this population comprehends speech in realistic adverse acoustical conditions. A study was conducted to investigate the effects of background noise level (BNL), reverberation time (RT), and talker foreign accent on native and non-native listeners' speech comprehension, while controlling for English language abilities. A total of 115 adult listeners completed comprehension tasks under 15 acoustic conditions: three BNLs (RC-30, RC-40, and RC-50) and five RTs (from 0.4 to 1.2 s). Fifty-six listeners were tested with speech from native …


Assessment Of Noise-Induced Annoyance By Tones In Noise From Building Mechanical Systems, Joonhee Lee, Lily M. Wang Apr 2016

Assessment Of Noise-Induced Annoyance By Tones In Noise From Building Mechanical Systems, Joonhee Lee, Lily M. Wang

Lily M Wang

Prominent tones in noise generated by mechanical equipment in buildings can cause complaints from occupants in buildings. The ISO 1996-2 and ANSI S1.13 standards describe methodologies and metrics to quantify tonality perception, but the influence of tones in noise on human annoyance and performance is not fully understood yet. This paper investigates annoyance responses of humans while exposed to background noise with tonal components. Twenty participants completed digit span tasks while exposed to noise signals with differing levels of tones and overall loudness. Subjects were also asked to rate their annoyance after completing tasks under each noise signal. The subjective …


The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang Apr 2016

The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang

Lily M Wang

The movement for improved classroom acoustics has primarily been grounded on studies that show how building acoustics (i.e. background noise levels and room reverberation) affect speech intelligibility, as determined by speech recognition tests. What about actual student learning, though? If students do not understand each spoken word in the classroom perfectly, can they still manage to achieve high scholastic success? This presentation will review two recent studies conducted at the University of Nebraska – Lincoln, linking classroom acoustic conditions to student learning outcomes and speech comprehension (rather than simply recognition). In the first, acoustic measurements in two public school districts …


Determining Annoyance Thresholds Of Tones In Noise, Jennifer M. Francis, Joonhee Lee, Lily M. Wang Apr 2016

Determining Annoyance Thresholds Of Tones In Noise, Jennifer M. Francis, Joonhee Lee, Lily M. Wang

Lily M Wang

Building services equipment often produces noise signatures with significant tones in them that can lead to complaints in the built environment. Previous studies have investigated prominence levels of assorted tonal frequencies, but it is still unclear what prominence of the tones across varying tonal frequencies can lead to human annoyance. This project seeks to apply two different methods towards defining annoyance thresholds of tones in noise at two tonal frequencies: 125 Hz and 500 Hz. In the first, subjects are asked to perform a task, while exposed to ten minutes of a broadband noise spectrum with a specific level of …


The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang Apr 2016

The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang

Lily M Wang

The movement for improved classroom acoustics has primarily been grounded on studies that show how building acoustics (i.e. background noise levels and room reverberation) affect speech intelligibility, as determined by speech recognition tests. What about actual student learning, though? If students do not understand each spoken word in the classroom perfectly, can they still manage to achieve high scholastic success? This presentation will review two recent studies conducted at the University of Nebraska – Lincoln, linking classroom acoustic conditions to student learning outcomes and speech comprehension (rather than simply recognition). In the first, acoustic measurements in two public school districts …


Effects Of Room Acoustics On Comprehension Of Foreign-Accented Speech By Native And Non-Native English-Speaking Listeners, Zhao Peng, Kristin E. Hanna, Brenna N. Boyd, Lily M. Wang Apr 2016

Effects Of Room Acoustics On Comprehension Of Foreign-Accented Speech By Native And Non-Native English-Speaking Listeners, Zhao Peng, Kristin E. Hanna, Brenna N. Boyd, Lily M. Wang

Lily M Wang

In a previous study by the authors, reverberation time (RT) and background noise level (BNL) were both found to have negative effects on native and non-native English-speaking listeners in comprehending English speech produced by native American-English-speaking talkers. Comprehension scores were adjusted for listeners’ baseline English proficiency levels. In the present study, instead of native English-speaking talkers, two native Mandarin Chinese talkers (one male, one female) with similar English spoken proficiency were recruited to produce the same speech materials used in the previous study. A similar methodology was adopted to conduct speech comprehension tests on three groups of listeners: 1) native …


Quantification And Subjective Perception Of Varying Reflection Densities In Measured Room Impulsed Responses, Hyun Hong, Lily M. Wang Apr 2016

Quantification And Subjective Perception Of Varying Reflection Densities In Measured Room Impulsed Responses, Hyun Hong, Lily M. Wang

Lily M Wang

This project focuses on quantifying and testing the subjective perception of reflection densities, or the number of reflections per second, from different room impulse responses. The widely used room acoustic metric, reverberation time, is linked to the perceived reverberation in a room. Two different rooms having the same reverberation time, though, can have different reflection densities in their room impulse responses, and this difference in reflection density may affect how listeners perceive spatial impression in rooms. To investigate how sensitive humans are to a change of reflection density, this paper first reviews assorted parameters for quantifying reflection density from measured …


Room Acoustic Effects On Speech Comprehension Of English-As-Second-Language Talkers And Listeners Versus Native-English-Speaking Talkers And Listeners, Lily M. Wang Apr 2016

Room Acoustic Effects On Speech Comprehension Of English-As-Second-Language Talkers And Listeners Versus Native-English-Speaking Talkers And Listeners, Lily M. Wang

Lily M Wang

Approximately 21% of the children in the United States school system speak a language other than English at home, but are being taught in English at school. English is additionally being used more and more often as a common language in international settings, even though participants at these international events again are not native English speakers. How do adverse room acoustic environments, including higher background noise levels and longer reverberation times, impact English-as-a-Second-Language (ESL) talkers and listeners versus native English-speaking talkers and listeners? This presentation focuses on two recent studies at the University of Nebraska that investigate how assorted room …