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AES Munich 2009
Poster Session P12

P12 - Loudspeakers

Friday, May 8, 13:30 — 15:00
P12-1 Reduction of Distortion in Conical Horn Loudspeakers at High LevelsSverre Holm, University of Oslo - Oslo, Norway; Rune Skramstad, Paragon Arrays - Drammen, Norway
Many horns have audible distortion at high levels. We measured a horn consisting of 6 conical sections with a 10-inch element at 99 dB SPL. A closed back gave maximum 2.4 percent second harmonic and 3.4 percent third harmonic distortion in the 100–1000 Hz range, while an open construction had 1.25 percent and 0.6 percent. A new semi-permeable back chamber reduced this to 0.7 percent and 0.35 percent. We hypothesize that the distortion is partly due to the non-linear compliance of air in the back chamber, and partly is due to the element’s interaction with the front and back loading of the horn, and that the new construction loads the element in a more optimal way.
Convention Paper 7717 (Purchase now)

P12-2 Comparison of Different Methods for the Subjective Sound Quality Evaluation of Compression DriversJosé Martínez, Acustica Beyma S.L. - Valencia, Spain; Joan Croañes, Escola Politecnica Superior de Gandia - Valencia, Spain; Jorge Francés Monllor Jaime Ramis, Universidad de Alicante - Alicante, Spain
In this paper an approach to the problem of sound quality evaluation of radiating systems is considered, applying a perceptual model. One of the objectives is to use the parameter proposed by Moore [. . .] to test if it provides satisfactory results when it is applied to the quality evaluation of indirect radiation loudspeakers. Three compression drives have been used for these proposals. Recordings with different test signals at different input voltages have been done. Using this experimental base, an approach to the problem from different points of view is done: [. . .] Taking in consideration classic sound quality parameters such as roughness, sharpness, and tonality. [. . .] Applying the parameter suggested by Moore obtained from the application of a perceptual model. Moreover, a psychoacoustic experiment has been made on a population of 25 people. The results, although preliminary and strongly dependant on the reference signal used to obtain Rnonlin, show a good correlation with the Rnonlin values.
Convention Paper 7718 (Purchase now)

P12-3 Membrane Modes in Transducers with the Direct D/A ConversionLibor Husník, Czech Technical University in Prague - Prague, Czech Republic
Operating principle of systems with the direct acoustic D/A conversion, which are sometimes called digital loudspeakers, brings new features to the field of transducer design. There are many design possibilities to these systems, using different transduction principles and spatial arrangement of constituting parts. This paper deals with the single-acting condenser transducer, suitable for micromachining applications, in which the membrane is driven by a partitioned back electrode. While in conventional transducers the electric force between the back electrode and the membrane is evenly distributed, in digital transducers it is no longer the case. Consequences to membrane vibrations for some cases of excitation by various distributions of forces representing given binary combinations from the dynamic level are presented.
Convention Paper 7719 (Purchase now)

P12-4 Increasing Active Radiating Factor of High-Frequency Horns by Using Staggered Arrangement in Loudspeaker Line ArrayKang An, Yong Shen, Aiping Zhang, Nanjing University - Nanjing, China
Active Radiating Factor (ARF) is an important parameter to analyze the loudspeaker line array when considering the gap between each two transducers, especially for high-frequency horns. As ARF is desired to be as high as possible, the staggered arrangement of horns is introduced in this paper. The responses in vertical direction and horizontal direction are analyzed. Compared with the conventional arrangement, the negative effects of gaps are reduced and responses are improved in simulation.
Convention Paper 7720 (Purchase now)