104 research outputs found
From MPA to strategically designed absorbers using solid freeform fabrication techniques
This paper reports on current work investigating the development of an alternative single material, broad frequency acoustic resonator by applying geometric changes to the cavity, without using sub-millimetre features. The inclusion of internal features such as fins and perforated layers are considered. The manufacture of these complex components is possible directly from CAD data via relatively new manufacturing techniques collectively know as Rapid Manufacturing. The technology has limitations for this application which are explored in the paper. Significant resistance however, has been achieved without the use of resistive materials or sub-millimeter features and significant improvements in peak absorption and increases in bandwidth over ¾ of an octave have been attained. These findings are currently being utilised in the development of a broad frequency absorber
Relationships between users
<p>' <b>average income and their evaluation of acoustics.</b> (a) Between income and evaluation of subjective loudness; (b) Between income and evaluation of acoustic comfort.</p
Basic information of the survey sites.
<p>The basic information includes size, sound sources, the number of interviews conducted, average SPL, average subjective loudness (1, very quiet; 2, quiet; 3, neither quiet nor loud; 4, loud; and 5, very loud) and acoustic comfort (1, very uncomfortable; 2, uncomfortable; 3, neither comfortable nor uncomfortable; 4, comfortable; and 5, very comfortable). ‘NI’ means number of interviews, ‘Aver. SL’ means average evaluation of subjective loudness, and ‘Aver.AC’ means average evaluation of acoustic comfort.</p
The effect of users' income and education on evaluation of acoustic comfort.
<p>The table shows multiple regression analysis <i>R</i><sub>adj</sub><sup>2</sup> with standardised coefficient between income or education level and evaluation of acoustic comfort, where the significance levels (2-tailed) are also shown, with <sup>**</sup> indicating <i>p</i><0.001.</p
Differences among occupations in terms of evaluation of subjective loudness and acoustic comfort.
<p>Differences among occupations in terms of evaluation of subjective loudness and acoustic comfort.</p
Relationships among income, education level, and occupation.
<p>The table shows chi-square test correlation coefficients between income and education level, and chi-square test contingency coefficients between occupation and income as well as education level, where the significance levels (2-tailed) are also shown, with ** indicating p<0.01, and * indicating p<0.05.</p
Relationships between users' frequency of visit and their evaluation of acoustics.
<p>(a) Between frequency of visit and evaluation of subjective loudness; (b) Between frequency of visit and evaluation of acoustic comfort.</p
Relationshipsbetween users' length of stay and their evaluation of acoustics.
<p>(a) Between length of stay and evaluation of subjective loudness; (b) Between length of stay and evaluation of acoustic comfort.</p
Relationships between users' evaluation of acoustic comfort and income, as well as education level.
<p>The table shows chi-square test correlation coefficients between income or education level and evaluation of acoustic comfort, when occupation is fixed as worker, where the significance levels (2-tailed) are also shown, with ** indicating p<0.01, and * indicating p<0.05.</p
Relationships between occupation and evaluation of acoustic comfort.
<p>The table shows chi-square test contingency coefficients between occupation and evaluation of acoustic comfort, when income or education is fixed at a level, namely income is from 151 to 300 US dollar, education level is graduate or higher, where the significance levels (2-tailed) are also shown, with ** indicating p<0.01, and *indicating p<0.05.</p
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