v7.0, 20040922, me

Saturday, October 30, 9:00 am – 10:30 am
Session J MICROPHONES

Chair: David Josephson, Josephson Engineering, San Jose, CA, USA

9:00 am
J-1 Long Range Noise Canceling Microphone—Alexander Goldin, Alango Ltd., Haifa, Israel
The paper presents Long Range Noise Canceling (LRNC) microphone array technology developed in Alango Ltd. LRNC is a digital signal processing technology utilizing near field signals from two unidirectional or four omnidirectional microphones. It allows differentiation between a user’s voice originating in a closed region in front of LRNC microphone and other sounds that are effectively blocked. The pick up range of the LRNC microphone may be as large as 70 cm in front of the microphone and, if necessary, may be easily reduced by changing corresponding software parameters. This unique property makes the LRNC microphone attractive for a variety of voice applications where distant sounds, noises or acoustic echoes must be blocked.
Convention Paper 6252

9:30 am
J-2 Spatial Definition and the PanAmbiophone Microphone Array for 2-D Surround and 3-D Fully Periphonic Recording—Robert (Robin) Miller III, FilmakerTechnology, Bethlehem, PA, USA
Higher sampling rates are necessary for high spectral resolution, but it is higher angular resolution and precision that preserves source directionality and therefore higher tonal/timbral quality of that source, termed spatial definition. In acoustic spaces that are extensions of musical instruments, voices, and sources of sound effects (as for movies), tonality is a major contributor to lifelike perception. But in audio reproduction, lifelike tonality is limited by the recording system. A surround microphone has been developed both for more precise 2-D surround (PanAmbio), compatible with ITU 5.1, and for “PerAmbio” 3-D (with height) for the ultimate in tonal reality, distributable using ordinary 6-channel media for either decoderless 2-D replay or 3-D with decoder and five additional speakers.
Convention Paper 6253

10:00 am
J-3 Advanced Simulation of a Condenser Microphone Capsule—Roger Grinnip III, Shure Incorporated, Niles, IL, USA
An advanced numerical model of a pressure condenser microphone capsule is presented. The model divides the acoustic space into internal and external domains and couples the dynamic pressure in each domain to the capsule diaphragm motion. The external acoustic space is modeled using the boundary element (BE) method, which allows for arbitrary geometry of the capsule/microphone external surface. The diaphragm is modeled as a circular tensioned membrane of negligible bending stiffness. The internal acoustic space (both the viscous air film and back chamber) is modeled as a cylindrical cavity with negligible axial pressure variation. Flow through the back plate is modeled as an annular array of circular pores with generalized functions locating each pore position. Although the presented model is specialized for a simple pressure condenser microphone, the numerical implementation is sufficiently generic to allow for a large variation in capsule parameters. The complete model, implemented in a software package called VC, is used to generate a simulated response curve that is compared to a response curve taken from an experimental prototype. The results show excellent agreement throughout the measured frequency range, indicating this new coupled model may be used for advanced microphone characterization and design.
Convention Paper 6254