Innovative Composite Materials for Sound Absorption and Insulation: Where We Are and Where We Are Going.

Materials with sound-absorbing or sound-insulating properties have been rapidly evolving in recent years due to several reasons [...

Performance Characterization of Broad Band Sustainable Sound Absorbers Made of Almond Skins.

In order to limit the environmental impact caused by the use of non-renewable resources, a growing research interest is currently being shown in the reuse of agricultural by-products as new raw materials for green building panels. Moreover, the European directives impose the goal of sustainability supporting the investigation of passive solutions for the reduction of energy consumption. Thus, the promotion of innovative building materials for the enhancement of acoustic and thermal insulation of the buildings is an important issue.

Publisher Correction: The Scales Project, a cross-national dataset on the interpretation of thermal perception scales.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Composite Eco-Friendly Sound Absorbing Materials Made of Recycled Textile Waste and Biopolymers.

In recent years, the interest in reusing recycled fibers as building materials has been growing as a consequence of their ability to reduce the production of waste and the use of virgin resources, taking advantage of the potential that fibrous materials may offer to improve thermal and acoustic comfort. Composite panels, made of 100% wool waste fibers and bound by means of either a chitosan solution and a gum Arabic solution, were tested and characterized in terms of acoustic and non-acoustic properties. Samples with a 5 cm thickness and different density values were made to investigate the influence of flow resistivity on the final performance.

The Scales Project, a cross-national dataset on the interpretation of thermal perception scales.

Thermal discomfort is one of the main triggers for occupants' interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers.

On-site acoustical characterization of Baroque tapestries: The Barberini collection at St. John the Divine Cathedral.

Tapestries represent an important and valuable cultural heritage. In the past they played a significant role in enriching indoor environments, as well as contributing to change the indoor characteristics of the space. Considering typical mounting conditions, acoustics was likely to be strongly affected by hung tapestries.

Acoustics of Italian Historical Opera Houses.

Opera houses represent a large group of performance spaces characterized by great complexity and, at the same time, versatility with respect to different usage (from opera to symphonic music and ballet). This kind of building originated in Italy during the 17th century and later spread across the country and then Europe and the rest of the world, slowly evolving into modern theatre shapes. As a consequence of the changes undergone by the interior space, the original acoustic features, which likely influenced many composers, experienced important variations.

[Working conditions for supermarket employees: from experimental data to best practices].

Background: Thermal, acoustic and visual comfort conditions for hypermarket workers have never been investigated with scientific methods.

Objectives: taking advantage of a case study, with characteristics capable of generalizing the results, analytically measure the actual comfort conditions to which workers are exposed and point out possible ameliorative proposals.

Methods: Carry out a detailed survey based on instrumental measurements combined with subjective questionnaires to assess the indoor environment.

Optimizing stepwise rotation of dodecahedron sound source to improve the accuracy of room acoustic measures.

Dodecahedron sound sources are widely used for acoustical measurement purposes as they produce a good approximation of omnidirectional radiation. Evidence shows that such an assumption is acceptable only in the low-frequency range (namely below 1 kHz), while at higher frequencies sound radiation is far from being uniform. In order to improve the accuracy of acoustical measurements obtained from dodecahedron sources, international standard ISO 3382 suggests an averaging of results after a source rotation.

On the sound absorption by openings in rooms (L).

Sound absorption by openings has been rarely considered in room acoustics. In fact, information about small openings (such as ventilation grids) may sometimes be found, but nothing is said about larger openings, possibly as a consequence of the less likely occurrence in a design. In order to fill this gap, measurements were carried out in scale models, measuring the equivalent absorption due to different openings and comparing it with theoretical results.

A comparative analysis of acoustic energy models for churches.

Different models to improve prediction of energy-based acoustic parameters in churches have been proposed by different researchers [E. Cirillo and F. Martellotta, J.

Identifying acoustical coupling by measurements and prediction-models for St. Peter's Basilica in Rome.

St. Peter's Basilica is one of the largest buildings in the world, having a huge volume resulting from the addition of different parts. Consequently, sound propagation cannot be interpreted using a conventional approach and requires experimental measures to be compared with statistical-acoustics and geometrical predictions in order to explain the interplay between shape, materials, and sound waves better.

A multi-rate decay model to predict energy-based acoustic parameters in churches (L).

Multi-rate decays are sometimes observed in room acoustics, appearing when markedly different volumes are coupled together and resulting in nonlinear decay curves. Such behavior appears in several churches at the very beginning of the decay process, although in conditions which cannot be explicitly referred to as coupling phenomena. Consequently, multi-rate exponential decays may be suitable to model energy distribution in this group of buildings, providing a more elegant and easily applicable set of equations in place of a previously defined "linear" model, used to adapt Barron's revised theory.

Sound propagation and energy relations in churches.

The results of an acoustic survey carried out in a group of Italian churches differing in style, typology, and location were used in order to study how the acoustic energy varies inside this kind of space. The effect of different architectural elements on sound propagation was investigated by means of three-dimensional impulse responses measured using a B-format microphone with sweep signals. Side chapels, columns, and trussed roofs appeared to scatter the reflections, so that the purely diffuse exponential sound decay begins after a time interval which grows with the source-receiver distance and with the complexity of the church.