We chose seven different positions in order to cover the whole audience area and to have significant sound files for different areas of the hall. The balconies on the side were studied too, and appeared to be well served by the sound since the first reflections came always from the side wall and thus the initial time delay was small.
Using the post processing from CATT acoustic software we created the impulse responses corresponding to each of those 7 positions. In order to auralize properly the concert hall we changed the directivity of the source to be closer to the reality (symphony). Using a bidirectional source which is aimed to the "center" of the room, seven impulse responses were thus created. Two convolutions per position were then processed, one with a symphonic song, and one with a trumpet song. The main goal for using those two songs is that one is really what is usually played on a concert hall so one can have a feeling of what the audience will perceived during a concert, and the other one is more used for its directivity patern. Indeed while the symphony music is sort of omnidirectional or at least concentrate to the audience, the trumpet is more focused in the front and is sort of limited in the distance compared to the very loud and low instruments which composed thesymphony (french horn, cello....). Because we designed this hall for music purpose we didn't auralize the hall with speech.
On the table below you will find all the sounds created from those convolution. The first table gathers the sound files from our main concert hall under study. The second table is used as a comparison, the sound files are created from the second concert hall with a special shape around the stage. We saw before the differences in the metrics and will now study the differences in the perceived sound.
Auralization with our first hall (shoebox style)
Listening to the different position in the shoebox shaped hall, one can say that the perceived reverberation time is approximatively the same. But things which differ somehow from a position to an other are the brilliance and the warmth. The lack of brilliance was also seen in the calculation of the metrcis. One can say that our hall can be then improved in applying materials which would enlarge the early decay time in high frequencies. The Bass ratios were pretty good from the calculations overall positions but one can say that small differences can easily be heard from a position to another. One must be very careful about that while designing a concert hall.
It is maybe easier to perceive it when listening to the trumpet sounds. The warmth differs a lot from one ot another position. While looking closer one can find that in the ground level the warmth is better than in the balcony level. If one would like to improve our concert hall one should start with the upper level. Changing the size of the reflectors, designing them bigger would maybe help the low frequencies to propagate in the upper level.
Nevertheless while listening to the initial sounds, even if one can hear this lack in low frequencies, the impression of envelopment is quite better thanks to the long reverberation time.
Auralization with our second hall ( stage shape)
The differences between the two rooms can be felt only for some positions and especially for the trumpet sound. The stage-shaped room seems to give more power to the trumpet; this can be due to the fact that the wall around the stage concentrate the energy of the trumpet and give faster reflections.
So for some position the angled walls seem to give better reflections. The reverberation is perceived as a bit smaller but it doesn't affect in a bad way the sound, it seems a bit more realistic.
One can then say that even the small differences in the metrics between the two rooms gives noticeable differencies in the perceived sound. The stage-shaped room might give better results at least for the hear.