Click here to purchase the entire book in PDF format. Fukada Tree This configuration, developed by Akira Fukada at NHK Japan was one of the first published recommendations for a microphone technique for ITU-775 surround [Fukada et al., 1997]. As can be seen in Figure 10.156, it consists of five widely spaced cardioids, each sending a signal to a single channel. In addition, two omnidirectional microphones are placed on the sides with each signal routed to two channels. Figure 10.156: Fukada Tree: a = b = c = 1 to 1.5 m, d = 0 to 2 m, L/R angle = 110$^\circ$ to 130$^\circ$, LS/RS angle = 60$^\circ$ to 90$^\circ$. This is a very useful technique, particularly in larger halls with big ensembles. The large separation of the front three cardioids prevents any detrimental comb filtering effects in the listening room on the direct sound of the ensemble (this problem is discussed above). One interesting thing to try with this configuration is to just listen to the five cardioid outputs with a large distance to the rear microphones. You will notice that, due to the large separation between the front and rear signals in the recording space, the perceived sound field in the listening room has two separate areas - that is to say that the frontal sound stage appears to be separate from the surround with nothing connecting them. This is caused by the low correlation between the front and rear signals. Fukada cures this problem by sending the outputs of the omnis to front and surround. The result is a very spacious soundfield, but with reasonably reliable imaging characteristics. You may notice some comb filtering effects caused by having identical signals in the L/LS and R/RS pairs, but you will have to listen carefully for them... Notice that the distance between the front array and rear pair of microphones can be as little as 0 m, therefore, there may be situations where all microphones but the centre are placed on a single boom.