Clarity (acoustics)
Clarity is a term introduced and defined in acoustics by R. Thiele to identify the audibility of rooms.
The term clarity was introduced in connection with measurements of the impulse response of rooms. See also the term reflectogram . First, the primary will sound as a direct signal registered in the increasingly dense intervals, the discards by sound reflections follow the boundary surfaces.
It is the generally accepted view today is that in the discards, within a period of about 100 to 200 ms after the direct sound in the ear , significant information for assessing arrive audibility contained a room. This was shown for the first time in particular by the studies by Helmut Haas ( Haas effect ), Erwin Meyer and G. Schodder. According to this, all throws (reflections) contribute to the increase in volume within about 50 ms after the primary sound , without disturbing the directional localization of the sound source or being noticed as an audible echo .
As a well-known Haas effect, this even applies to discards - depending on the time difference - which are up to 10 dB stronger than direct sound. So quantitatively clarified the long-known fact that the intelligibility with increasing distance r from the sound source in a room much less rapidly decreases than outdoors because of having 1 / r falling sound pressure is "refreshed" by additional discards again.
In order to obtain a single criterion from the partially detailed backlash sequences, it made sense, neglecting the fine structure, to add the sound energy to the direct sound within the first 50 ms and to relate it to the total sound energy incident after an impulse excitation. Here is the definition of the degree of clarity:
Mean:
- D = clarity
- p = sound pressure
- t = time
See also
literature
- R. Thiele: Directional distribution and time sequence of sound reflections in rooms . In: Acustica . tape 3 , 1953, pp. 291-302 .