Abstract: An earpiece comprises a suction cup sensor, a preamplifier, a potentiometer for varying the gain of the amplifier, a pass band filter and electronic means enabling the user to adjust the central frequency and/or the width of the pass band of the filter. One application of the invention is the construction of self-contained and individualized telephone handsets or headphones which may be connected without any wire connection on any telephone set.

Abstract: The invention relates to active acoustic absorber devices for absorbing the sounds which are emitted by a emitter source and which propagate therefrom, along a pipe. An absorber according to the invention comprises an acoustic tripole which is composed of two auxiliary acoustic sources which constitute a dipole and of a third auxiliary source which constitutes a unipole, these three sources being located in the same acoustic chamber, which chamber is disposed outside the pipe, opens therein through three orifices aligned parallel to the longitudinal axis of the pipe and comprises a transverse plane of symmetry perpendicular to the axis of the pipe.