Basic requirements on sound-track system.

Basic requirements on sound-track set are taken mostly from the recommendations „ANSI PH22.202M-1984 „American National Standard for Motion Pictures – B chain (final chain) electro-acoustic response – Control Rooms and Indoor Theaters“. In the point a.) the intelligibility is required on predominant majority of hearing area at least as „good“. The points e.) up to g.) are based on operational experience.

a.) Phonetic recognizibility greater than 85% secured by the ratio of acoustic energy of the direct and diffuse component of the sound field in the places of hearing greater than 0,205 as minimum for 80 per cent of visitors.

b.) Maximum average level of the whole acoustic pressure at least 85 dB at excitation of the sound-track set by the wide-band noise signal (rosy noise) at least 80 per cent of the hearing area with maximum unevennesses ±6 dB.

c.) The sound-track set excited according to the point b.) must be dimensioned with the reserve +10 dB for transfer of the peaks of non-stationary signals.

d.) The average frequency course, meaured by rosy noise bands, should be in tolerance band ±3 dB in frequency range 250 Hz – 2 kHz, allowable drop outside this band –3 dB/okt with tolerance band ±3 dB.

e.) In case of simultaneously use of sound-track system and microphones the set must work with the stability reserve at least 6 dB.

f.) Sufficient variability and easiness of control of the sound-track set.

g.) Modifiability of the individual parts of the set by its modernization or its extension.

The sound track system must meet all these requirements with minimum compromises!