A loudspeaker horn is described, which produces good coupling of sound to the atmosphere, while avoiding perturbations in magnitude and phase that would produce large narrow-frequency losses or transient distortions. The horn includes a major sound-reflective portion of typical horn shape, and also includes a buffer extending around the large end of the horn. The buffer has a sound absorption coefficient about halfway between the almost zero absorption coefficient of the major portion of the boundary walls of the horn and the 100% absorption coefficient of the ambient atmosphere, to couple sound to the atmosphere more efficiently, and with an efficiency that is relatively constant with frequency. A horn of largely rectangular cross-section, has corner regions covered with highly sound absorbing material, to minimize transient distortions such as "ringing".
An improved acoustic horn for loudspeakers is provided. The acoustic horn of the referred embodiment of the present invention includes a one piece body that incorporates damping material within the body. Preferably, the one piece body is slotted and vibration damping material is provided within the slots. The horn is fabricated by casting from suitable metals and metal alloys. In the preferred embodiment, the body comprises four outwardly curved and flared side walls and is generally rectangular. Each wall of a pair of the opposed side walls is cast with a slot. Vibration damping material is provided in each slot to substantially reduce the structural resonances of the one piece body, so that the acoustic horn has enhanced vibration damping. Various vibration damping materials that are flexible relative to the body and have a high loss tangent are used. Suitable materials include hot melt adhesives, epoxy resins, and commercially available elastomeric materials.
A speaker system which has a speaker unit with a diaphragm and an acoustic path provided on the front side of the diaphragm so as to guide sound waves emitted from the diaphragm. The acoustic path is defined by a sound absorbing member. The space in the acoustic path and the sound absorbing member is separated by a partition member which is disposed in such a manner that at least a portion of the sound absorbing member is exposed to the space in the acoustic path, except that the portion of the sound absorbing member just adjacent the diaphragm is not exposed to the acoustic path. This arrangement eliminates peaks and troughs of resonance determined by the length of the acoustic path, so that flat sound pressure frequency characteristics can be obtained over a wide range up to high-pitch tone region.
Improvements in a moving-coil loudspeaker system of the type incorporating motional feedback. An accelerometer mounted on the loudspeaker coil to develop the feedback signal is enclosed within an air-tight shield can to avoid low-frequency instability. High-frequency stability is enhanced by various means including use of a "trumpet" shaped speaker cone, an inverted (concave) dust cap, and theta-dependent cone variations such as providing clusters of holes through the speaker cone to alter the propagation of sound waves radially in selected sectors of the cone. Also disclosed is the use of weights placed on the loudspeaker coil in selected locations circumferentially with respect to the accelerometer to minimize instability effects.
A coaxial speaker assembly (10) with reduced sound distortion, sound time delay, and polar response distortion. The coaxial speaker assembly (10) includes a high-frequency speaker system (16) mounted coaxially with and fitting within a lower-frequency speaker system (14). A baffle (50) is secured to a diaphragm (48) of the high-frequency speaker system (16). A step-down ledge (52) is circumferentially positioned adjacent to the baffle (50) and extends outwardly therefrom. A portion of the sound waves emanating from the high-frequency diaphragm (48) are reflected off the step-down ledge (52).
A unidirectional microphone element can be embedded within an object and be made flush to the object's surface yet retain its directional discrimination characteristic. Acoustic waveguides transmit acoustic input signals from acoustic ports to the front and rear input ports of the microphone element while also providing intelligibility-enhancing frequency response shaping. The housing wherein the microphone element is mounted acoustically isolates the front and rear input ports of the microphone element.
