Abstract: In a planar loudspeaker structure comprising planar membrane for forming a diaphragm on which a voice coil of a conductor pattern is formed, and a magnetic circuit for supplying a DC magnetic flux which crosses the voice coil, the conductor pattern includes first and second zigzag conductor pattern portions which are juxtaposed on substantially the entire area of the membrane and connected in series. Opposite ends of the series connection of the first and second conductor pattern portions are respectively connected to first and second terminals for receiving a low-band component of an input audio signal. A high-band component of the input signal is applied to a third terminal connected to a junction between the first and second conductor pattern portions and supplied only to the second conductor pattern portion.

Abstract: An earphone characteristic measuring device comprises an acoustic coupler having an acoustic tube simulated to an external auditory canal in which an earphone under measurement is to be inserted and an acoustic tube of a smaller diameter having an acoustic impedance of approximately 320 ohms connected to an end of the first acoustic tube, a sound source for emitting an impulse sound to the acoustic coupler, a microphone mounted at the end of the first acoustic tube for picking up sound pressure information and a characteristic calculation circuit for transforming an earphone characteristic of the acoustic coupler to an earphone characteristic of a real ear based on an input impedance of the acoustic coupler viewed from an end of the earphone inserted in the acoustic coupler and an input impedance of the real ear represented by a sum of an eardrum impedance of the real ear and an external auditory canal volume of the real ear, stored in a memory in response to the sound pressure information from the microphone

Abstract: A horn speaker having wide directional characteristics in accordance with the present invention provides a horn having a horn wall the shape of which is formed by connecting a plurality of curves having different flaring constants. The flaring constant of the curve forming a mouth portion of the horn wall is selected so as to be greater than that of the curve forming a throat portion thereof. The mouth portion of the horn wall is shaped so as to have a flaring angle which is formed by the curve at the mouth portion and has no abrupt variation of angle to a baffle plate. The curve at the mouth portion is connected with the curve at the horn wall nearer to the throat portion and having the flaring constant different therefrom at a point at which the differential coefficients of the respective curves substantially coincide with each other.