Abstract: A method and an apparatus for filtering an audio signal include the steps of making the audio signal available in digitalized form, wherein the duration of the sampling interval is half or less than half of the period duration of the highest frequency to be expected in the audio signal, a digitalized impulse response is made available in accordance with the desired filtering effect, and a convolution sum is formed from the samples of the impulse response and the samples of the audio signal, wherein, (i) several adjacent samples of the impulse response define a corresponding interval within at least a time portion of the impulse response which is shorter than the impulse response, (ii) within the interval defined in this manner, the samples of the impulse response corresponding to the interval defined in this manner are equated to a value which is a function of one or more of the samples of the digitalized impulse response falling within the interval defined in this manner, and (iii) the steps (i) and (ii) are

Abstract: A monaural communication device is composed of a housing for receiving a receiver and a support component which is resiliently connected to the housing and is to be worn binaurally. The support component is constructed symmetrically and the housing and/or the support component is provided with grip elements which, when actuated, make it possible to fold or tilt the support component away from the housing by using the fingers of only one hand, and wherein, when the support component carries out a return movement by means of a spring, the support component clamps the pinna against the housing.

Abstract: A method of simulating a room impression and/or sound impression occurring at a representative listening location in a room with monophonic, stereophonic or multichannel reproduction includes selecting a room whose sound is to be simulated. A location of a representative listening location is then determined. Subsequently, the corresponding room impulse response at least for one channel is determined at the representative listening location. A threshold value which exceeds over at least a portion of the duration of the determined room impulse response is determined for the determined room impulse response. By comparing the determined room impulse response with the threshold value, a reduced room impulse response is produced which within the portion of the duration of the determined room impulse response only includes those contents of the determined room impulse response in which a momentary amplitude is above the threshold value.

Abstract: A diaphragm with moving coil for electrodynamic transducers has in the center thereof a spherically-shaped portion and adjacent to the spherically-shaped portion a toroidally-shaped zone which may be provided with corrugations. An outwardly diverging, truncated cone-shaped collar is placed on the spherically-shaped portion. The collar may be of the same material as the diaphragm. The collar has a circular rim which is mechanically fixedly connected to the spherically-shaped portion. The circular rim of the collar has a smaller diameter than the moving coil.

Abstract: A helical UHF transmitting and/or receiving antenna for electromagnetic waves in the frequency range of between 400 MHz and 1000 MHz. The helical antenna is arranged within a closed housing which is permeable to HF radiation. The UHF signal is supplied to an end of the helical antenna through a coaxial connector. The helix of the antenna has at least one and a half turns but not more than ten turns. Diameter, height and total length of the antenna wire are very small in comparison to the wave length. A mechanically-operated device permits a continuous change of the height of the antenna helix in axial direction thereof or of the diameter transversely of the antenna axis.

Abstract: A microphone arrangement comprising at least two individual microphones arranged closely next to each other, whose individual microphones depending on the recording angle desired for the sound recording are a pressure- and/or a pressure gradient receiver and/or a directional line microphone, is characterized by the wind pressure being continuously measured during the sound recording by means of a microphone (Mw) with downstream switched electronic circuit (5, 11, 12) and depending on the respectively prevailing wind pressure always that microphone (M1, M2, Mn) remains switched to the amplifier 9 assigned to it by an instantaneously controlled switch (6, 7, 8), which in its conversion principle, frequency course and its directional effect is least sensitive to wind noises for the prevailing wind intensity.

Abstract: A stereophonic binaural recording and reproduction method for audio signals presented to headsets. Signals of the left stereo channel are supplied to the left ear, weighted with the outer ear transmission function of the left ear for the angle range of between 0.degree. to 45.degree. to the left of the median plane, and to the right ear, weighted with the outer ear transmission function of the right ear for the same angle range. Additionally, time-delayed signals of the left stereo channel are supplied to the right ear, weighted with the outer ear transmission function of this ear for the opposite angle range, wherein the delay is markedly outside of the time range of the sum localization and of the audible echo. The signals of the right stereo channel are supplied to the right and left ear in the same manner but mirror-inverted relative to the median plane.

Abstract: A device for the stereophonic recording of sound events by means of two microphones arranged with essentially oppositely directed orientation and mounted in replicas of the human head. The microphones are mounted in the replicas of the outer auditory meatus. The replica of the human head is limited to the replicas of the pinnae with the outer auditory meatus. Microphones with unilateral pickup effect are used and are mounted preferably in positions corresponding to the positions of the pinna openings in human heads. The microphones operate in the low-frequency range of up to approximately 1500 Hz as directional microphones and, in the frequency range above approximately 1500 Hz, operate with spectral resolution of the outer ear transmission function. The device according to the present invention provides compatibility of headset reproduction and loudspeaker reproduction.

Abstract: An elastic or shock-absorbing support member for a microphone. The support member includes a single hose member shaped in the form of an elastic loop. In comparison to its other dimensions, the elastic loop has a very thin wall and an inner diameter which is approximately twice the width of the loop. The loop connects a clamping piece supporting the microphone or the microphone housing to a connecting piece of a tripod.

Abstract: A resiliently fastened support device for supporting an arrangement carrying a microphone, such as, a tripod tube, a gooseneck, a plug-type connection or the like. The support device is connected to an end of the arrangement which faces away from the microphone. The mass of the support device is a multiple of the mass of the microphone and the arrangement carrying the microphone.

Abstract: A UHF-feedback oscillator for a frequency range of at least 300 MHz to 1000 MHz includes an amplifier stage, a voltage controlled tuning filter and a feedback quadripole. The feedback quadripole comprises a two- or three- loop helical waveguide resonator. Thus, the oscillator is easily adjustable to its oscillating condition within the very wideband frequency range of between 300 MHz and 1000 MHz and can be miniaturized in the simplest manner.

Abstract: A pressure gradient pickup, particularly a capacitor microphone or a dynamic microphone, has a diaphragm arranged in a housing and at least one sound entry opening which conducts the sound to the rear side of the diaphragm. Acoustically acting phase-shifting sections are connected in the interior of the housing to the at least one sound entry opening. The at least one sound entry opening is located at least approximately in the same plane as the diaphragm and is preferably arranged concentrically relative to the diaphragm edge.

Abstract: A directional microphone operating according to the electrostatic or electrodynamic transducer principle. The pickup effect of the microphone is determined by a single phase-shifting delay line section between the rear side of the active transducer diaphragm and at least one sound entry opening provided in the microphone housing at a distance behind the plane of the diaphragm. The microphone includes at least one acoustic element coupled to the delay line section. The delay line section is arranged with the acoustic element or elements so as to have a lower limit frequency in the range of 300 Hz.

Abstract: An ear pad for earphones comprises a foam-like material formed into a pad enclosing the user's ear in use in order to expand the essentially linear frequency response of a good earphone so that it brings also the lowest still audible frequencies into the linear region, and simultaneously with the expansion of the transmission range of the earphone, to make the reproduction of stereophonic acoustic events more natural. The ear pad is advantageously shaped and made of open-cell elastic foam material having on its inner and/or its outer side or in its interior so as to be disposed in the sound path from the coupling space outward, at least one passive membrane supported for vibration and having a natural resonance which lies in the range of the lower frequencies.

Abstract: An electrostatic transducer with a diaphragm supported by means of a stretching ring, and a back plate which is formed by a thin metal plate supported on a carrier member and mounted spaced apart from the diaphragm. A plurality of support members are attached to the carrier member and distributed over the area of the carrier member. The base plate is glued to the free ends of the support members. In this transducer, the use of very thin metal plate as back plates is possible.

Abstract: A protective breathing mask, in addition to having a speaking diaphragm for close communication is equipped with an electroacoustic transducer system for indirect speech transmission from inside the mask. In order to achieve high transmission quality for human speech with a simple apparatus without the occurrence of interference noise, it is provided that the sound output channel is closed on the mask side by an auxiliary diaphragm which is acoustically coupled with the speaking diaphragm via a secondary air chamber, and is also mechanically connected directly or indirectly with a movable element of the electroacoustic transducer system.

Abstract: Acoustic frictional resistance comprises a plate having at least one laser-formed hole therethrough. The plate is formed by positioning a plate preferably one having a thickness smaller than one and one-half milimeters alongside a laser and directing the laser beam so that it cuts a hole through the plate. During the process of producing the resistance, the value of the acoustic friction is measured as a pressure drop of a constant air stream or as an expenditure of electrical energy for an electrically excited electroacoustic transducer. This measurement is then used as a variable or as a standard for controlling the process. Advantageously, a coherent beam is emitted by the laser which is deflected by mirror from a horizontal to a vertical direction and focused by means of a lens to work in a contact-free manner on a workpiece supported on a support member such as a movable table. By moving the table in two coordinate directions, a plurality of bores are formed in a pattern in a workpiece.

Abstract: A circuit in an electroacoustic transmission system suppresses amplitude peaks which are caused by the utterance of a stop consonant such as a "P". A microphone of the transmission system has an output which a high-pass filter is connected. The high-pass filter is normally inactive but can be activated by an electronic switch for a brief period of time. The switch is controlled by a train of electronic elements functioning as a detector for detecting a characteristic quiescent or pause period before the explosive discharge of the stop consonant. Upon detecting this pause the electronic switch is activated and held activated for about 10 to 30 ms. During that time the peak occurs but is suppressed in that it is not passed by the high-pass filter which is activated during this time.

Abstract: An ear piece for a sound producing device such as a headset comprises an annular ear cushion with at least one part of an elastic, soft, sound permeable foam and at least one other part of a sound permeable layer which is thin in relation to the overall thickness of the air cushion and has a defined acoustic impedance for low and medium frequencies of the audibility range. The ear cushion acts as a frictional resistance with a central portion defining coupling space from the sound producing device to the ear and representing an acoustic connection through the sound producing device to the air.