Patent mentions: ATCO's NeoPlanar for sound suppression.
patft.uspto.gov;
Mechanical-electromagnetic, rotary, (MER), internal combustion engines appear to be a largely unexplored class of engines. The use of high temperature materials and self-lubricating bearings may spawn truly remarkable engines. A MER engine with a pair of 4 bladed, hinged-hub, impellers may have an improved balance of forces. Exhaust sound suppression systems could likely contribute to environmental improvement, for example: "Neoplanar" TM, "a thin film (1/8 inch) magnetic transducer", made by American Technology Corp., may produce "anti-sound".
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Pratt & Whitney:
patft.uspto.gov
patft.uspto.gov;
ATCO's HSS for medical environments:
Other References
Technology Licensing-HyperSonic Sound, American Technology Corporation, Internet Document: atcsd.com, printed on Jan. 15, 2002.
The sound source used is preferably a parametric loudspeaker. In a parametric loudspeaker a modulated, inaudible ultrasound signal is produced and the nonlinearity of the acoustic characteristics of air are utilized. Because of this nonlinearity, the air acts as a demodulator, the demodulated signal being present as audible sound. Since ultrasound waves are used as a carrier for the audible sound and can be emitted with a relatively small opening angle in the range of a few degrees of arc, the antisound can be produced in a locally limited manner and specifically at the point where the operating noise disturbs the relevant person, that is to say is perceived by the latter. In particular, the opening angle is at most 15°, preferably at most 5°. The functioning of such a highly directive loudspeaker is explained in more detail, for example, on the Internet page www.atcsd.com/tl_hss/html, as at Jan. 15, 2002, from the American Technology Corporation. Because of the intensive directional action, only the patient perceives the antisound intended for him, while the operator is located outside the closely limited region ensonified by the parametric loudspeaker. The operator then does not perceive the antisound as additional noise which increases the overall noise level, as opposed to the related art. If a parametric loudspeaker is used, there is additionally no direct contact between the patient and the sound source or another part used for the acoustic transmission. Therefore, no specific hygienic measures have to be taken either for the sound source.
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Abstract
An exciting sound wave generator is positioned within a nacelle of a jet engine at its inlet to generate an exciting sound wave having a primary frequency generally different from a frequency of the primary tone of the noise. The exciting sound wave is used to modulate the primary tone of the noise and, therefore, distribute sound energy of the noise from the primary tone to a broad range of side bands so that the amplitude of the primary tone of the noise is reduced.
Pratt & Whitney |
