HISTORY OF ACOUSTICALLY

The need for A.T. appeared in as soon as there has been a sound system reproducing speech with the image (The , 1929). The most common technique consists in many tiny holes in the screen material. From lengthy experiments, the size of holes has been defined around 1mm in diameter, spaced so as to cover about 3% to 6% of the overall screen surface. Even further information can be found at : www.filmsound.org/film-sound-history

Screens for the industry, mainly for coporate applications, usually are not because there is no need to synchronise the sound with the image : in most applications, the only sound consists in live comments upon the displayed program.

The advent of in the 90’s revealed the need to adapt the A.T. screens to video projection, as the projected programs were mainly movies or concert videos needing . The first adaptation came from micro-perforations , reducing the dimension of the holes to about 0.5 mm, and increasing their number to preserve the same surface .

It was often objected that the was not sufficient to provide a good sound quality : The screens behaved like filters, needing HF equalisation. Further, there was a loss in light refraction (typically about 10%) which was a concern as most of the CRT projectors were operating near to their limits in light output. However, the benefit of placing the centre speaker in the proper place, behind the centre of the screens, allowing coherence and correct was so obvious and dramatic that the micro-perforated screens became the standard for installations.

By teh end of teh 20th century, however, the became the new standard of the industry. This aroused a major problem, as the projected grilles of pixels came to interfere with the patterns of micro-perforations, creating unacceptable moiré effects. The micro-perforated screens simply became not compatible with most .

An unexpected solution had been found in Japan, as far back as 1994, when a screen fabric made of woven cloth was developed (JAES, Vol 42 N°12), only in the scope of improving the audio performance. More recently, Screen Excellence developed its fabrics range. This new designs combine uncompromised performance with a level of unmatched by any micro-perforated .