However, in measurement standards and prediction tools EDT is often defined by the straight line that best fits the data set in the range of 0 to –10dB. Early Decay Time (EDT) could be defined as 6 times the time interval from 0dB to -10dB on the decay curve, Figure 2. More often, RT is calculated from the time interval from -5dB to -35dB on the decay curve, and denoted RT30 or T30. The time it takes for this slope to decay by 60dB is defined as the reverberation time RT60. The ideal decay curve, occurring in a perfect diffuse sound field, is a sloping straight line. The latter may leave a complex auditive impression (including echoes), despite the simple character of the first. ![]() if comparing the aftersound following the final chord from a choir with the aftersound following the impulse from a percussive instrument in the same room. Therefore, it is to be expected that a single number representation like the Reverberation Time (RT) correlates better with the perception of the aftersound, than with the perception of an impulse response. the decay curves of the aftersound (here: the reverberation after a sound source stops, not to be confused with the aftersound in our hearing). In contrast, such simple slopes are much more prominent in the down-step response, i.e. excess absorption in the floor-ceiling axis, leaving a reverberant sound field remaining between a pair or a quadruple of hard walls Another common example is the remaining energy slope from an undamped, coupled room.Ī simple decay slope can be represented by a single number with unit dB/s.Īlthough the impulse response has an overall decaying tendency, its level-time curve deviates significantly from a simple slope, making it difficult to determine a single number representing the reverberation properly. The double slope decay typically occurs if the sound absorption is unevenly distributed, e.g. In its simplest form, the slope is a single straight line falling with a tendency close to 60dB / RT, typical for reverberant sound fields with even spatial distribution at frequencies lower than the Schroeder Frequency ~2000
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |