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AES Amsterdam 2008
Microphones and Loudspeakers
Poster Session P5
Saturday, May 17, 14:00 — 15:30
P5-1 A Study of Electrostatic Forces in Single-Acting Condenser Digital Transducer—Libor Husník, Czech Technical University in Prague - Prague, Czech Republic
One of the possibilities to design a transducer with the direct digital-to-analog conversion, sometimes called a digital loudspeaker, is the miniature condenser transducer manufactured on a silicon chip. Only recently has this micro technology been made available commercially, which can open further application possibilities. This paper is aimed at the study in which the back electrode of the electrostatic transducer is partitioned into sections having total areas proportional to powers of 2. Since electrostatic force acting on the membrane is affected by the distribution of bit groups, which cannot be even, said electrostatic force will not be a linear function of the signal voltage. Correcting coefficients for some arrangements are searched for.
Convention Paper 7341 (Purchase now)
P5-2 Ultra-Thin Micro-Loudspeaker Using Oblique Magnetic Circuit—Toshiyuki Matsumura, Shuji Saiki, Sawako Usuki, Matsushita Electric Industrial Co., Ltd. - Kadoma City, Osaka, Japan; Koji Sano, Panasonic Electronic Devices Co., Ltd. - Matsusaka City, Japan
More and more functions are installed to a mobile phone, but the size of the handset has become smaller. Devices installed in the mobile phone have been required to be downsized or thinner. Micro-loudspeakers installed to the mobile phone are required to be thinner. They are required to become both thinner and reproduce high quality sound. However, it has been very difficult to make thinner micro-loudspeakers without deteriorating the acoustic performance because the structure of conventional dynamic micro-loudspeaker is not suitable to make it thinner. We have succeeded in developing an ultra-thin micro-loudspeaker using Oblique Magnetic Circuit, which is 1.5 mm thick (45% thinner than conventional dynamic micro-loudspeakers) without deteriorating the acoustic performance.
Convention Paper 7342 (Purchase now)
P5-3 A Novel Glass Laminated Structure for Flat Panel Loudspeakers—Olivier Mal, Marek Novotny, Bart Verbeeren, AGC Research & Development Centre - Jumet, Belgium; Neil Harris, New Transducers Ltd. (NXT) - Cambourne, UK
A new, patented “sandwich structure” has been developed for various audio applications, in which thin glass sheets are laminated with a special PVB (Polyvinyl Butyral) film to eliminate typical acoustical weaknesses of monolithic glass and standard laminated solutions. The glass improvements include suppression of ringing of the audio signal and a much more flexible and lightweight glass structure. It results in flatter frequency response (both on-axis and 180° power response) and better transport of vibrations in the glass surface. In addition, better acoustical sensitivity and mechanical resistance are achieved. In this paper, after defining the structure of the developed laminated glass solution, we compare its performances to previously tried monolithic and laminated glass solutions. We also emphasize the key factors influencing the final acoustical properties. Finally, we introduce potential application fields for the developed structure.
Convention Paper 7343 (Purchase now)
P5-4 A Digitally Direct Driven Dynamic-Type Loudspeaker—Ryota Saito, Akira Yasuda, Kazushige Kuroki, Tomohiro Tsuchiya, Naoto Shinkawa, Hosei University - Koganei, Tokyo, Japan
If a speaker can be driven digitally, all processes from the input to the output can be performed digitally without the use of analog components such as power amplifiers; and a small, light, and high-quality speaker system can be realized. In this paper we propose the basic principle behind Digital-Speaker, and a digitally driven dynamic-type loudspeaker provided with multiple voice coils employing multibit delta-sigma modulation. The piezoelectric-speaker used in our previous study is replaced by the voice coil. The prototype is implemented along with a FPGA, CMOS drivers, and a dynamic-type loudspeaker. The THD and SPL are approximately 0.1% and 104 dB, respectively, and the output power is 1 W even when the power supply voltage is 1 V.
Convention Paper 7344 (Purchase now)
P5-5 Accelerated Power Test Analysis Based on Loudspeaker Life Distribution—Xu Wang, Yong Shen, Zhicheng Wu, Nanjing University - Nanjing, China
For the loudspeaker manufacturers, the long time spent on power tests made by relative standards or buyers has deeply influenced the period of product design and development. The authors apply the theory of reliability to cut the duration of loudspeaker power tests. On the basis of experiment data, a model of loudspeaker life distribution is propounded, from which an accelerated factor of the loudspeaker power test is derived, and then the characteristics of the loudspeaker under normal working conditions can be estimated. The method can be conveniently used on relative power tests and shorten the duration of the tests effectively.
Convention Paper 7345 (Purchase now)
P5-6 Perception and Physical Behavior of Loudspeaker Nonlinearities at Bass Frequencies in Closed vs. Reflex Enclosures—Jukka Rauhala, Jukka Ahonen, Miikka Tikander, Matti Karjalainen, Helsinki University of Technology - Espoo, Finland
This paper examines loudspeaker nonlinearities at bass frequencies in closed and reflex enclosures using signal analysis and perceptual evaluation methods. The nonlinearities are investigated by driving the loudspeakers to be compared with sinusoidal and musical test tones. The produced responses are evaluated in terms of diaphragm displacement, harmonic distortion, and bandwise distortion. In addition, a listening experiment is conducted in order to determine how the nonlinearities are perceived in both reflex and closed enclosures. The results show that with signals that have energy close to the tuning frequency of the reflex port produce more distortion with the closed enclosure. On the other hand, acoustic bass test tone behaved in an opposite way causing more distortion with the reflex enclosure. These phenomena were verified with the listening tests.
Convention Paper 7346 (Purchase now)
Last Updated: 20080612, tendeloo