We have a new article for a numerical investigation on the sound insulation of ventilation windows which has been published in the Applied Acoustics. Please visit the journal website in this link.
Near-field/far-field array manifold of an acoustic vector-sensor near a reflecting boundary
There is a new publication regarding the use of acoustic vector-sensor (a.k.a. the vector hydrophone) near a reflecting boundary. The article is published in the Journal of the Acoustical Society of America. Please visit this link.
Classroom Acoustics Session at ASA meeting in Salt Lake City
Dr Siu-Kit Lau and Prof Shiu-Keung Tang have chaired a session of Classroom Acoustics at the 171st Meeting of Acoustical Society of America in Salt Lake City on 23-27 May 2016. During the meeting, Prof Tang and Dr Lau presented a paper entitled “Cantonese speech intelligibility tests in two Hong Kong primary school classrooms”. Abstract of the presentation can be found at this link. A preliminary observation is that there is higher probability for the pupils to give wrong answers when the sound of a character lasts for relatively long duration, especially when there are abrupt temporal changes in the time-frequency spectra. Correct answers are usually given when the corresponding time-frequency spectral energy is more concentrated within a short duration.
Mad Scientist
Salt Lake City (Church)
Investigation of Chinese word recognition scores of children in primary school classroom with different speech sound pressure levels
New article for an investigation of Chinese word recognition scores of children in primary school classroom has been published. Please visit the journal website in this link.
Abstract:
Chinese word recognition (CWR) test was conducted by grades 3 and 5 children under the different conditions of reverberation time (RT), background noise level (BNL) and speech sound pressure level (SSPL) in three primary-school classrooms. The CWR scores and signal to noise ratios (SNRs) have been obtained at listening positions. Results show that the CWR score for grades 3 and 5 children increases with increase of SSPL, decrease of RT or increase of age, but it decreases with increase of BNL under the same conditions. For a mixed noise of 56 dBA (speech-spectrum-like noise and ambient noise), the CWR scores in the classroom for grades 3 and 5 children reach a peak at SNR of 15–20 dBA under the same RT and age of children condition. For the natural ambient noise, the CWR score for grades 3 and 5 children gradually increases with increase of the SNR. The high SSPL could not guarantee good CWR for children in classroom, which also depends on RT and BNL in classroom. When the classroom has long RT or high BNL, the increase of SSPL would not be necessarily to achieve better CWR. The novelty of the present study is to further evaluate and confirm the results under environments of real classrooms (not simulated room in laboratory).
Classroom of a school in China
An impedance-mobility model of acoustic metamaterials
A fast prediction method for the performance of stacked membrane-type metamaterials has been developed using An impedance-mobility model. Matthew Blevins of the University of Nebraska-Lincoln introduced the method and a Matlab platform regarding this approach at the Spring 2015 meeting of Acoustical Society of America. The work is collaborated and supervised by Dr. Siu-Kit Lau and Dr. Lily Wang. Metamaterials are man-made materials to have properties that have not yet been found in nature. Membrane-type acoustic metamaterials have been proven to exhibit high low-frequency transmission loss despite their small thickness and light weight. The efficient model based on the impedance-mobility can be used to facilitate design and optimization of stacked membrane-type acoustic metamaterials.
Abstract (metamaterials) of the presentation in the ASA meeting spring 2015 in Pittsburgh, PA
The 11th International Conference on Green and Energy-Efficient Building & New Technologies
The 11th International Conference on Green and Energy-Efficient Building & New Technologies and Products Expo has been held in Beijing on March 24 and 25. Dr. Siu-Kit Lau has been invited for a speech regarding the current research at classroom acoustics in China. Results have been compared with a recent study in UK. There are other professionals sharing their studies and experiences in green campus development.
A Major Element for Health, Wellbeing and Productivity of Staff
Acoustics in Offices:
— A Major Element for Health, Wellbeing and Productivity of Staff
Typical Business Operation Cost (Source: http://www.worldgbc.org)
Recently, a new report from the World Green Building Council (WGBC) finds “overwhelming evidence” that office design significantly impacts the health, wellbeing and productivity of staff.
Staff costs typically accounts for 90% of business operating costs. A study in 1998 found that there was up to a 66% drop in performance for a ’memory for prose’ task when participants were exposed to different types of background noise. A follow-up study by the same authors in 2005 found that 99% of people surveyed reported that their concentration was impaired by office noise such as unanswered phones and background speech.
Background sound levels need to drown out unwanted distraction, but not be too loud to cause stress, therefore a background sound level of 45dBA is recommended in open plan offices. In private or cellular offices the background sound levels can be reduced to 40dBA. In both cases, any higher and that background sound itself risks becoming a distraction.
For more details about the report, it is kindly suggested to visit the link below.
http://www.worldgbc.org/activities/health-wellbeing-productivity-offices .
An investigation of acoustic treatment for children in a classroom of an elementary school
The South China Univeristy of Technology and Dr. Lau of Armstrong have compared the objective acoustic parameters and students’ subjective responses before and after an acoustic treatment in an elementary-school classroom. Acoustic treatment was done by installing sound absorption materials on the ceiling of the classroom for control of sound reverberation. The effects of reverberation time on children’s speech recognition have also been investigated. Results show that (1) the objective acoustic parameters in the classroom were obviously improved; (2) the subjective loudness of different types of noise sources, that students experienced in the classroom, were reduced; and (3) the speech intelligibility was significantly improved in the classroom after the acoustic treatment.
The article can be found from this link.
Certificate of Reviewing from Applied Acoustics (Journal)
Elsevier Certificate 2014
Dr. Siu-Kit (Eddie) Lau awarded a Certificate of Reviewing from Applied Acoustics (Journal).
The 21st International Congress on Sound and Vibration in Beijing
The 21st International Congress on Sound and Vibration (ICSV 21) has been held in Beijing, China from July 13-17, 2014. Dr. Siu-Kit Lau has presented a study of the acoustic comfort in the hospital of Palomar Pomerado Health (PPH). The study has evaluated the effects of flooring and ceiling choices on controlling “corridor activity noise” in an occupied hospital. Before the meeting, we had a gathering with Prof. Jian Tian (Chairman of ICSV 21), Prof. Jian Kang (University of Sheffield), Prof. Joseph Lai (University of New South Wales), Mr. Maurice Yeung (HK-EPD), Dr. Siu-Kit Lau and many others.
Prof. Jian Tian, Prof. Jian Kang, Prof. Joseph Lai, Maurice Yeung, Dr. Siu-Kit Lau and many others
Prof. Jian Tian, Prof. Jian Kang, Prof. Joseph Lai, Maurice Yeung, Dr. Siu-Kit Lau and many others
Prof. Jian Tian, Prof. Jian Kang, Prof. Joseph Lai, Maurice Yeung, Dr. Siu-Kit Lau and many others