Abstract: Disclosed herein is a digital audio tone evaluating system comprising an analyzer for subjecting a digital signal related to voice and/or music to signal processing, thereby operating a factor which expresses the auditory tone quality of the voice and/or the music by the digital signal in a digitized form. The system can objectively evaluate auditory tone quality by digital audio.

Abstract: A circuit and method are disclosed for improving low frequency characteristics in a speaker by detecting the motion of a vibration system of the speaker to be fed back to the vibration system. The circuit detects the motion signal by bridge-balancing the input and output signals of the speaker to detect a voltage difference therebetween. Low frequency reproduction characteristics of the speaker are compensated by reducing lowest resonance frequency characteristics of the speaker and at the same time compensating intrinsic impedance characteristics thereof. The audio signal being reproduced is detected by bridge-balancing the output of the speaker, and dynamic impedance caused by the vibration system is detected by calculating the difference between the detected audio signal and an audio signal applied to the speaker.

Abstract: An acoustic diaphragm for speakers having a sandwich structure constituted by a core material comprising an elongated web material bent to have a plurality of radial projections, and upper and lower surface members adhered to the upper and lower edges of the core member, as well as a method of producing the same. The acoustic diaphragm of the invention has a reduced weight while exhibiting a large flexural rigidity so that the nodal line during the resonance vibration can have a circular form which in turn offers a circular form of nodal line and increased speaker power. Also, the method of producing the invention permits easy fabrication of the acoustic diaphragm having a sandwich structure.

Abstract: A multi-stylus printing head cell in which a plurality of styli or electrodes are placed in and bonded to a plurality of parallel grooves formed in one of the major surfaces of a base in such a way that one end portions of the styli may extended out of the base; the exposed conductors of a flat flexible cable are overlaid upon the styli and made into electrical connection therewith; a retaining plate is placed over the exposed conductors; and the legs or side walls of a U-shaped holder are folded inwards over the retaining plate, whereby the base, the styli, the flat flexible cable, the retainer and the holder may be securely held as a unitary construction.