The goal of this laboratory work is to examine and hopefully confirm earlier published results regarding 5 different room types handling the perception of reproduced sound quality in studio rooms.
By using the software CATT one design a assignated room type from the list below:
The evaluation of the different room types is done by both a binaural listening test as well as an ambisonic one. For the binaural part, the following parameters will be considered for each room type. Note that the text in the list is quoted from the lab-pm - RAC_2010_1_lab_task_instructions.pdf available at the home page.
LEDE design of a room generally points to the use of a studio for recording a sound. General aim point for the design is to first distinguish the so called listening area where the technician or similar will acquire the best listening experience. Once this area is defined the room is divided into two parts, where the front section of the room will be defined as source or Dead-End. This area further includes the so called sweet spot designed in the first place. The second part will be referred to as receiving area or Live-End.
The Dead-End generally features a substantial amount of absorption in comparison to the Live-End. This to avoid the influence of the unwanted and quite powerful early reflections. By dividing the room into two parts – where the absorption between the parts clearly differs – one will create a receiving part of the room that will manage to retain the natural ambiance of the room. This though by adding further physical acoustical factors, such as diffusers with various designs.
By designing a studio in this way, one create an environment where the reflections preferably is controlled instead of eliminated. Early reflections is being withdrawn from the listening area and the second wave will preferably be diffused.
Further, one wants to eliminate eventual flutter echo and standing waves between the front and back of the room. By the need of keeping the receive end of the room as live as possible, the absorptive area for the back wall in the source part preferably becomes predominant in comparison to the receiving part.
Considering the low frequency components, bass traps is of great importance when designing a LEDE-room and a studio. As seen in Figure 1 above, possible and preferable placement of bass traps relates to the corners of the Dead-End. Simply, bass traps may consist for example of hanging heavy fabrics or placing absorptive panels at for example wall, ceiling or in corners. The behavior of sound waves in the lower frequencies become somewhat omni-directional and will therefore find its way behind the source position – leaving an eventual flutter echo present between the previously mentioned back and front wall. By adding further absorptive material to walls and ceiling – as well as diffusers of irregular size and shape – one will further improve the desired ambiance of the room.
HomeFor this lab task, our group was assigned a so called LEDE room with a flat response.
When modelling the LEDE room we followed the standard and set the front part of the room to be highly absorbative and the back of the room to be highly diffusive. The ceiling was also divided into a absorbing front part and a diffusive back part. Since we wanted to achieve a flat response we made the room highly absorbative and highly diffusive in each octave band. In real life the high absorption in lower frequencies could be made possible by using an outer shell. The model also included the most common features as a glas window for visual communication between the studio engineer and the musician and a simple mixing table as well as a table in the back. We tried to simulate a standard studio set-up. The model can be seen in figure 2.
In this chapter the measured/calculated impulse responses in CATT is presented, see Figure 3 and 4 below respectively.
Left
Right
In this chapter the measured/calculated frequency responses in CATT is presented, see Figure 3 and 4 below respectively.
Left
Right
In this section the data acquired in the listening test is presented.
HomeThe experienced ASW for our room is presented below in Figure 7,8,9,10,11 and 12 - for each sound sample respectively.< /p>
The experienced phantom sources is presented below in Figure 13. The sound samples handled a left and right channel, which of one of them was delayed 0.9ms, 1.5ms or 2ms. The grading is from 4 to 0 (C), where 4 indicate a completely shift to the left channel.
In Figure 14 below, the experienced envelopment from the listening test is presented. The diagram is supposed to interpreted from above - where for example left and right side of the circle represent the left and right ear, respectively.
Til this date - 2 may 2010, no data for this part has been available. Thereof the presentation is quite hard to manage..
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