Acoustical effects of columns, beams and furniture on sound fields in small enclosures
In acoustic design of small enclosures, it is a considerably important matter to control eigenmodes at low frequencies, so that many researches have been done on the effect of overall shapes of rooms on the eigenmodes, such as optimization of room dimensions ratio. However, overall room shapes are usually restricted to rectangular forms due to easy construction, therefore it is desirable to improve sound fields only by changing partial elements in rectangular rooms. In the present paper, the effects of additional elements, such as columns, beams and furniture, on the sound field in a small rectangular room are investigated through wave-based numerical analysis. Supposing a room for listening use with a loudspeaker, the effects are evaluated regarding the flatness of frequency response and the uniformity of spatial distribution in a listening area. The results show that: the effect of columns is small but more than beams; that of closed-type shelves is relatively large but not so much as open-type shelves; the size and the arrangement of every element have unnegligible effects. It is also seen that the additional elements generally lead to positive effects in flatness of frequency response and special uniformity even at low frequencies, although in a specific case.
Sounds of Etruria: aural characteristics of the Tomba dell'Orco, Tarquinia
Abstract This article presents the results of an archaeoacoustic analysis conducted inside the three chambers of the fourth-century BC Etruscan painted tomb of Tomba dell'Orco at Tarquinia. Using digital sound samples and an acoustic recording protocol, the study demonstrates how, in some areas of the tomb, low-frequency sounds, such as drumming and chanting, produce lengthy reverberation times. These effects may have been associated with the natural rumble of thunder, which played a significant role in Etruscan society, as indicated in secondary literary sources and material culture. The study provides a more comprehensive understanding of the Etruscan tomb space, while identifying new avenues of research in pre-Roman and other ancient Mediterranean funerary contexts.
Application of a finite-element model to low-frequency sound insulation in dwellings.
The sound transmission between adjacent rooms has been modeled using a finite-element method. Predicted sound-level difference gave good agreement with experimental data using a full-scale and a quarter-scale model. Results show that the sound insulation characteristics of a party wall at low frequencies strongly depend on the modal characteristics of the sound field of both rooms and of the partition. The effect of three edge conditions of the separating wall on the sound-level difference at low frequencies was examined: simply supported, clamped, and a combination of clamped and simply supported. It is demonstrated that a clamped partition provides greater sound-level difference at low frequencies than a simply supported. It also is confirmed that the sound-pressure level difference is lower in equal room than in unequal room configurations.