Effects of early and late reflections on intelligibility of reverberated speech by cochlear implant listeners

This is the published version, also available here: http://dx.doi.org/10.1121/1.4834455.The purpose of this study was to determine the overall impact of early and late reflections on the intelligibility of reverberated speech by cochlear implant listeners. Two specific reverberation times were assessed. For each reverberation time, sentences were presented in three different conditions wherein the target signal was filtered through the early, late or entire part of the acoustic impulse response. Results obtained with seven cochlear implant listeners indicated that while early reflections neither enhanced nor reduced overall speech perception performance, late reflections severely reduced speech intelligibility in both reverberant conditions tested

Localization of a Virtual Wall by Means of Active Echolocation by Untrained Sighted Persons

The active sensing and perception of the environment by auditory means is typically known as echolocation and it can be acquired by humans, who can profit from it in the absence of vision. We investigated the ability of twentyone untrained sighted participants to use echolocation with self-generated oral clicks for aligning themselves within the horizontal plane towards a virtual wall, emulated with an acoustic virtual reality system, at distances between 1 and 32 m, in the absence of background noise and reverberation. Participants were able to detect the virtual wall on 61% of the trials, although with large di↵erences across individuals and distances. The use of louder and shorter clicks led to an increased performance, whereas the use of clicks with lower frequency content allowed for the use of interaural time di↵erences to improve the accuracy of reflection localization at very long distances. The distance of 2 m was the most difficult to detect and localize, whereas the furthest distances of 16 and 32 m were the easiest ones. Thus, echolocation may be used e↵ectively to identify large distant environmental landmarks such as buildings

Economical decision making by Temnothorax albipennis ant colonies.

Contains fulltext : 144537.pdf (publisher's version ) (Open Access

Evaluating a distortion-weighted glimpsing metric for predicting binaural speech intelligibility in rooms

A distortion-weighted glimpse proportion metric (BiDWGP) for predicting binaural speech intelligibility were evaluated in simulated anechoic and reverberant conditions, with and without a noise masker. The predictive performance of BiDWGP was compared to four reference binaural intelligibility metrics, which were extended from the Speech Intelligibility Index (SII) and the Speech Transmission Index (STI). In the anechoic sound field, BiDWGP demonstrated high accuracy in predicting binaural intelligibility for individual maskers (ρ ≥ 0.95) and across maskers (ρ ≥ 0.94). The reference metrics however performed less well in across-masker prediction (0.54 ≤ ρ ≤ 0.86) despite reasonable accuracy for individual maskers. In reverberant rooms, BiDWGP was more stable in all test conditions (ρ ≥ 0.87) than the reference metrics, which showed different predictive patterns: the binaural STIs were more robust for the stationary than for the fluctuating noise masker, whilst the binaural SII displayed the opposite behaviour. The study shows that the new BiDWGP metric can provide similar or even more robust predictive power than the current standard metric

Acoustic Properties of Absorbing Materials

Thanks to the progress made in materials research and to the introduction of innovative manufacturing technologies, a wide range of sound-absorbing elements are currently available to adjust the acoustic features of an environment [...

Sound insulation properties of handmade multilayered recycled material panels: an experimental and analytical investigation

Reusing recycled materials, such as end-of-life household materials, and exploiting their properties for a new purpose, different from the original one, is a topic of current relevance and in line with the principles of the circular economy model. This study focuses on the sound insulation properties of a handmade multi-layered panel made of recycled materials and intended for improving the indoor comfort of dwellings in vulnerable contexts. An experimental investigation has been conducted on a panel composed as follows: perforated cardboard, perforated paper egg box core filled with loose polyester and cardboard. Some acoustic measurements were performed in sound transmissions rooms according to the ISO 10140-2 standard and provided the Sound Reduction Index R of the panel and its weighed sound reduction index Rw, according to ISO 717-1 standard. The main goal of the present paper is to investigate which analytical model can be applied in order to predict the experimentally obtained results. In case the model is able to correctly describe the acoustic performances with a good approximation, it will also allow the prediction of the sound insulation performances for similar panels: operating on the geometry, thickness or layer sequence, it will be possible to achieve different sound insulation performances, according to specific requirements

Acoustic applications of bio-mycelium composites, current trends and opportunities: a systematic literature review

Growing environmental concerns and climate change have motivated researchers to find alternatives to traditional synthetic or polymer-based materials. An alternative group of materials that have gained recent interest are mycelium-based foams and composites, due to their sustainable nature and application potential. Mycelium consists in the vegetative growth of filamentous fungi, which binds organic matter through a network of hyphal micro-filaments in a natural biological process. Owing to these properties and their porous nature, mycelium bio-composites are versatile materials that can provide thermal insulation and are suitable for packaging systems, among other kinds of products. Also, mycelium-based sound absorbers have been developed, providing effective broadband absorption at mid to high frequencies. Mycelium bio-composites can also be shaped into different forms using a range of techniques such as molding and 3D printing. Together with their acoustic and thermal properties, this versatility establishes a promising potential for implementation in metamaterial structures with custom-designed acoustic absorption properties. In this work, we explore the versatility of mycelium bio-composites and the current trends in their acoustic applications by presenting a systematic literature review that assesses their acoustic performance, for a selected range of organic substrates and types of fungi, shaped and treated in different ways