Thursday, September 29, 9:00 am — 10:30 am (Rm 403A)
Alexander Voishvillo, JBL/Harman Professional Solutions - Northridge, CA, USA
P1-1 Holographic Nearfield Measurement of Loudspeaker Directivity—Wolfgang Klippel, Klippel GmbH - Dresden, Germany; Christian Bellmann, Klippel GmbH - Dresden, Germany
The acoustical output of loudspeaker systems is usually measured in the far field under anechoic conditions requiring a large measurement distance and special treatment of the room (absorbing room boundaries, air condition). Also the measurements of directivity characteristics at sufficient angular resolution are also very time consuming. The measurement in the near field of the sound source provides significant benefits (dominant direct sound, higher SNR, less climate impact) but requires a scanning process and a holographic processing of the measured data. This paper describes the theoretical basis of the new measurement technique and the practical consequences for the loudspeaker diagnostics.
Convention Paper 9598 (Purchase now)
P1-2 Fully Coupled Time Domain Simulation of Loudspeaker Transducer Motors—Andri Bezzola, Samsung Research America - Valencia, CA USA; Pascal Brunet, Samsung Research America - Valencia, CA USA; Audio Group - Digital Media Solutions
We present a novel time-dependent simulation method to calculate the response of a loudspeaker motor. The model allows for the simulation of complex signals and predicts the large-signal behavior including motor nonlinearities using only the motor geometry and material parameters without the need to measure physical samples. The transient large-signal simulation is made possible by the implementation of a moving-mesh algorithm for the displacement of the voice coil. Two motor geometries are simulated with different input signals, ranging from simple sine to complex random signals. The method provides previously unavailable insight into effects of flux modulation. The results are validated against a lumped parameter model and experimental measurements. The presented method can be used to compare different motor geometries before the prototyping stage, which is a useful tool for loudspeaker transducer engineers.
Convention Paper 9599 (Purchase now)
P1-3 Necessary Delay and Non-Causal Identification for Online Loudspeaker Modelling Considering Voice Coil Inductance—Rong Hu, Cirrus Logic - Austin, TX, USA; Jie Su, Cirrus Logic - Austin, TX, USA
The authors revisit the topic of online electrical system identification with adaptive filters for dynamic loudspeakers and investigate into the causality of the plant loudspeaker systems to be identified. The effects of the non-causal portion of plant system are analyzed and simulated results establish the link between the non-causality in impulse response and the voice coil inductance. The improvements of introducing necessary delay to the desired signal are proposed to enable the characterization of such non-causality. The proposed architecture with small delay extends the working bandwidth of online loudspeaker system identification and improves the accuracy of existing adaptive identification schemes without delays, which are traditionally restricted to run at low frequency bands.
Convention Paper 9600 (Purchase now)