No abstract

In this article, we show that visual distance perception (VDP) is influenced by the auditory environmental context through reverberation-related cues. We performed two VDP experiments in two dark rooms with extremely different reverberation times: an anechoic chamber and a reverberant room. Subjects assigned to the reverberant room perceived the targets farther than subjects assigned to the anechoic chamber. Also, we found a positive correlation between the maximum perceived distance and the auditorily perceived room size. We next performed a second experiment in which the same subjects of Experiment 1 were interchanged between rooms. We found that subjects preserved the responses from the previous experiment provided they were compatible with the present perception of the environment; if not, perceived distance was biased towards the auditorily perceived boundaries of the room. Results of both experiments show that the auditory environment can influence VDP, presumably through reverberation cues related to the perception of room size.

In Argentina, the teaching of acoustics is included in the curricula of several academic institutions, being a part of the technical instruction received both in undergraduate and graduate majors. Acoustics is part of numerous college and technical careers, several of which will be detailed during this presentation. At the same time, a large number of post graduate and extension training classes are offered by the same and other institutions. It is only fair to mention that the Engineering School of the Buenos Aires University was the pioneer in teaching this discipline in Argentina, when Electroacoustics started to be taught in 1956 as a mandatory subject in the formerly joint Electronics Engineering plan, thus enabling the formation of the Acoustic and Electroacoustic Laboratory of the Faculty, a laboratory that still exists. Shortly after, in October 1961, the Acoustic and Lighting Research Center was founded in the Architecture and Urbanism School at the Cordoba National University. The extensive growth and ramifications we have seen so far make the list unavoidably incomplete, since the present possibilities of learning this science in the country is too large to be exposed, allowing us a reduced mention and a brief exposure.

To elaborate noise maps, national and international directives indicate that urban noise measurements must be carried out 4 m high, so as to obtain the map by the method of direct measurements, or for the calibration of mathematical models that predict sound levels. As a continuation of research plans to be carried out in the Acoustic and Lighting Laboratory of the Commission of Scientific Research, Province of Buenos Aires (LAL—CIC), and in the Acoustic and Electroacoustic Laboratory, Engineering Faculty of the University of Buenos Aires (LACEAC—FI UBA), and in order to estimate the error that will be committed using the prediction method rather than the direct measuring method, urban noise measurements were taken in surrounding areas in a quick access to La Plata City, at different heights and different distances from the sound source.

Microperforated panels have been studied as a good, interesting absorbing element. In previous papers the properties of high absorption obtained in a wide frequency band was demonstrated, based on the impedance of the very small perforations. The perforation area ratio, the diameter of the holes, the thickness of the panel, and the density and viscosity of the air are the terms that define the sound absorption provided by the element. The microperforated panels have a simple structure and it is possible to build single or double resonators, in order to obtain a wide band response. An orifice may be considered as a short tube. Many years ago, Rayleigh and Crandall studied the propagation of sound in small tubes, of a very short length compared to wavelength. They found a high acoustics resistance and a very small reactance. So, the microperforated panel can be used as a dissipative element. An experimental investigation was carried out on different samples of microperforated panels, in order to obtain their sound absorption coefficient and so verify the validity of the mathematical models. Microperforated panels have been developed to cover a welding cabin internally, where classical absorbents are useless. (To be presented in Spanish.)