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Multichannel horizontal surround sound with a regular loudspeaker configuration
Published in Bosun Xie, Spatial Sound, 2023
Equation (4.3.38) is equivalent to the signals recorded with a set of cardioid microphones with their main axes pointing to each direction θi. Figure 4.15 (b) presents the polar pattern of the response of the cardioid microphone. This solution of reproduction signals is termed the in-phase solution because the negative rear lobe is eliminated in the polar pattern. A comparison between Figures 4.4 and 4.15 indicates that the magnitude of the out-of-phase rear lobe for b=2 is smaller than that of b = 2, which is between the magnitude of b = 1 and b = 2. For b = 1 given in Equation (4.3.37), the virtual source direction for a fixed head is evaluated with Equation (4.3.23): sinθI=12sinθS
Surround sound recording techniques
Published in Francis Rumsey, Spatial Audio, 2012
Theile proposes a front microphone arrangement shown in Figure 7.8. While superficially similar to the front arrays described in Section 7.1.2, he reduces crosstalk between the channels by the use of supercardioid microphones at ±90° for the left and right channels and a cardioid for the centre. (Supercardioids are more directional than cardioids and have the highest direct/reverberant pickup ratio of any first-order directional microphone. They have a smaller rear lobe than hypercardioids.) Theile's rationale behind this proposal is the avoidance of crosstalk between the front segments. He proposes to enhance the LF response of the array by using a hybrid microphone for left and right, that crosses over to omni below 100 Hz, thereby restoring the otherwise poor LF response. The centre channel is high pass filtered above 100 Hz. Furthermore, the response of the supercardioids should be equalised to have a flat response to signals at about 30° to the front of the array (they would normally sound quite coloured at this angle). Such a proposal demands some fairly complex microphone mounting, and possibly the development of a hybrid capsule with appropriate crossover and equalisation. A home-made version could also possibly be constructed. Schoeps has developed a prototype of this array, and it has been christened ‘OCT’ for ‘Optimum Cardioid Triangle’.
An Introduction to Sound, Hearing and Perception
Published in Nick Zacharov, Sensory Evaluation of Sound, 2018
Another important property in microphones is the sensitivity to sound from different directions, also known as the directional pattern. A pressure microphone has an omnidirectional pattern, which means it is equally sensitive all directions. If the directional pattern is a dipole that reacts at the main axis from front and back but not from the sides, the microphone is sensitive to the velocity of particles in air. A cardioid microphone, which is a useful compromise, is maximally sensitivity from the front and minimally sensitivity from the rear. It is also possible to construct highly directional microphones that are sensitive mainly to sound coming from a narrow spatial angle.
Mathematics and engineering in real life through mathematical competitions
Published in International Journal of Mathematical Education in Science and Technology, 2018
Figure 1 shows parabola tracing as the T-shaped slider with string tied at point F on top of the ruler and A is held taut along the ruler by a pencil at the point B. Figure 2 depicts a Cardioid as rotation of point D on the circumference of the revolving outer circle. Hohenwarter et al. [10] stated that such interactive constructions have the potential to facilitate the teaching of certain calculus concepts and that students can benefit from the integration of dynamic visualizations into their ‘traditional’ calculus classes.