The most common noise sources in buildings are related to Heating, Ventilating and Air Conditioning (HVAC) systems, plumbing systems, electrical systems and exterior sources. Passive Noise Control ...(PNC) techniques in buildings have been implemented in several ways. The aim of this work is to analyses the use of silencer to attenuate the noise in the ducts that are part of the ventilation systems in buildings, internal combustion systems, fans, gas conduction systems, boilers, etc. The main objective of a silencer is to reduce the transmission of noise, disturbing as little as possible the circulation of gas or liquid. In the first instance, the silencers are classified as reactive and dissipative, depending on whether the attenuation of the noise is produced by reflective or dissipative mechanisms, respectively. In a reactive silencer, the losses occur essentially due to the reflections of the sound waves in impedance discontinuities, such as widening or narrowing of the tube. In dissipative silencers, the flow is in contact with a large surface of absorbent material. The attenuation of the noise is then produced by visco-thermal losses in the porous material. In this work, a practical issue will be addressed with a noise reduction of 19 dBA in 60 Hz.
Practical application
Noise is a current issue in residential areas that could lead to health problems for people. The origin of these noises within buildings is very diverse, one of them is produced by ducts. Appling the PNC technique in modern building construction would be a good prevention practice. For this reason, in this project a PNC system was carried out in the ducts of a residential building, which could be used as a praiseworthy solution, avoiding problems for the inhabitants of these spaces.
Affective stimuli have been extensively used in emotion research for a better understanding of emotion regulation. Sound ratings, specifically non-verbal sounds, are biased by demographic indicators ...such as sex and nationality. Therefore, it is crucial to characterize sounds prior to their use in emotion research. This study aims to validate the IADS-2 database and additional sounds in a sample from the Mexican population. Three hundred twenty-nine participants born and raised in Mexico remotely listened to 174 sounds in monophonic format. They rated sounds according to the valence-arousal-dominance model using the Self-Assessment Manikin test. Results positively correlated to those of previous studies. Sex differences were observed only in dominance between female and male groups, contrary to the results from Portuguese, American and Japanese validations. Geographic region analysis demonstrated differences in arousal, indicating the need for additional research on occident and south regions. Furthermore, when conducting affective research, headphones and audio quality should be considered, primarily to reduce variability due to audio-related aspects, and to avoid changes in emotional experience. Finally, this study supports the feasibility of remote affective sound experiments over the internet as reported in previous research.
Acoustic characterizations of different locations are necessary to obtain relevant information on their behavior, particularly in the case of places that have not been fully understood or which ...purpose is still unknown since they are from cultures that no longer exist. Acoustic measurements were conducted in the archaeological zone of Edzna to obtain useful information to better understand the customs and practices of its past inhabitants. The information obtained from these acoustic measurements is presented in a dataset, which includes measurements taken at 32 points around the entire archaeological zone, with special attention given to the Main Plaza, the Great Acropolis, and the Little Acropolis. Two recording systems were used for this purpose: a microphone and a binaural head. As a result, a measurement database with the following characteristics was obtained: it comprises a total of 32 measurement points with 4 different sound source positions. In total, there are 297 files divided into separate folders. The sampling frequency used was 96 kHz, and the files are in mat format.
Acoustics has been integrated with archaeology to better understand the social and cultural context of past cultures. Specifically, public events such as rituals or ceremonies, where an appreciation ...of sound propagation was required to hold an event. Various acoustic techniques have been used to study archaeological sites, providing information about the building characteristics and organizational structures of ancient civilizations. This review aims to present recent advances in Archaeoacoustics worldwide over the last seven years (2016–2022). For this purpose, one hundred and five articles were identified and categorized into two topics: (1) Archaeoacoustics in places, and (2) Archaeoacoustics of musical instruments and pieces. In the first topic, three subtopics were identified: (1) measurement and characterization of places, (2) rock art, and (3) simulation, auralization, and virtualization. Regarding the first subtopic, it was identified that the standards for reverberation times in enclosures are generally applied in their development. In the second subtopic, it was determined that the places selected to make paintings were areas with long reverberation time. The last subtopic, simulation, auralization, and virtualization, is the area of most remarkable growth and innovation. Finally, this review opens the debate to seek standardization of a measurement method that allows comparing results from different investigations.
Mouth sounds serve several purposes, from the clinical diagnosis of diseases to emotional recognition. The following review aims to synthesize and discuss the different methods to apply, extract, ...analyze, and classify the acoustic features of mouth sounds. The most analyzed features were the zero-crossing rate, power/energy-based, and amplitude-based features in the time domain; and tonal-based, spectral-based, and cepstral features in the frequency domain. Regarding acoustic feature analysis, t-tests, variations of analysis of variance, and Pearson’s correlation tests were the most-used statistical tests used for feature evaluation, while the support vector machine and gaussian mixture models were the most used machine learning methods for pattern recognition. Neural networks were employed according to data availability. The main applications of mouth sound research were physical and mental condition monitoring. Nonetheless, other applications, such as communication, were included in the review. Finally, the limitations of the studies are discussed, indicating the need for standard procedures for mouth sound acquisition and analysis.
•Acoustic measurements of Edzna archaeological zone.•Analysis of the Reverberation time and Clarity of Edzna.•Evaluation of the acoustic properties of the Edzna archaeological zone.•Assessment of the ...historical acoustic conditions and their influence on the site's significance.•Implications for restoring the acoustic heritage of Edzna.
Over the years, numerous acoustic measurements have been made to examine archaeological spaces, providing valuable insights into how sound played a role in several cultures throughout history. This research found twenty-eight studies worldwide in the last seven years (2016 – 2022); twenty in Europe (e.g., Stonehenge in England or the Palace of Charles V in Spain); four in Asia (e.g., Rachmaninov Hall in Russia); three in America (e.g., Mexico City Cathedral in Mexico); and one in Africa (Iwan masjids in Egypt). However, there has been limited investigation into the acoustics of cultures in America such as the Incas, Aztecs, Mapuches, Patagones, or Guaranies. The Mayan zone, in particular the archaeological site of Edzna (Campeche, Mexico) is not an exception. This work presents a practical and portable acoustic measurement of this site to determine if the architectural spaces were designed considering sound effects. Edzna is organized in six main places: (1) Main Plaza, (2) Nohochna, (3) Great Acropolis, (4) Five-story building, (5) Small Acropolis and (6) Ballcourt. Acoustic measurements for this study were taken in the Main Plaza, the Great Acropolis, and the Small Acropolis. This study revealed that the archaeological zone presents high Reverberation Time (RT20) levels above 2 or 3 s. In particular, the RT20 of the Main Plaza (RT20 = 2.2 s on average), suggests that the space was used for crowded events where participants could listen around the plaza. In contrast, the Great and Small Acropolis (RT20 = 1.2 s on average) were probably used for private, more intimate events.
