Abstract: A method and apparatus for providing coder independent packet replacement in the presence of frame erasures without requiring that modifications be made to either the encoder or the decoder. An input buffer management process identifies the presence of lost or missing packets and informs a playout buffer management process therof. Then, when packets have been lost, the playout buffer management process advantageously synthesizes an actual signal segment in the absence of a corresponding decoded packet.

Abstract: A method and apparatus for substantially reducing tonal noise and or vibration generated by a rotating machine. The power supplied to the rotating machine or motor drive signal is modulated as a function of time so that the shaft rate of the rotating machine is varied as a function of time. The motor drive signal or power signal can be modulated in an alternating current (AC) machine wherein the shaft rate is related to the power line frequency, as well as a direct current (DC) machine wherein the shaft rate is related to the DC level applied, to alter the shaft rate as a function of time. Such drive power modulation causes the drive signal energy to spread into new frequencies. As a result, the radiated tonal components are spread out such that the strength of the rotating machine's tonal radiation is substantially reduced. In addition, "beating" effects related to the operation of multiple machines can be reduced.

Abstract: Flow-induced noise affecting microphones used in such applications as cellular phones is reduced by providing a deflector, made of an acoustically transmissive, high flow resistance material, disposed at a certain distance from the microphone pressure sensing area. The distance between the pressure sensing are and the deflector may be determined experimentally in consideration of any space constraints imposed by the specific application, and for cellular phones in particular, is approximately as little as 2 or 3 mm from the outside surface of the deflector.

Abstract: Method and apparatus for the active cancellation of broad band noise and/or single frequency tones emanating from rotating machinery, such as an air moving device, by detecting related mechanical and acoustic signals therein and causing canceling vibrations to be applied directly to the rotating machinery by a transducer.

Abstract: An air moving device such as an axial cooling fan comprises a rotatable shaft assembly and a plurality of fan blades coupled to the rotatable shaft assembly, each of the fan blades having a trailing edge when the rotatable shaft assembly is rotated in a given direction. In accordance with one illustrative embodiment of the invention, at least one of the fan blades has a sound reducing material attached thereto alongside the trailing edge thereof. The sound reducing material reduces aeroacoustic noise by reducing the aerodynamic effect that occurs when turbulence produced by the pressure differential between the two sides of one blade comes into contact either with the trailing edge of the given blade which created it, or, more significantly, with the following blade, at or near that blade's trailing edge.

Abstract: Option-equippable apparatus such as a computer that is not fully equipped with option circuit boards (14) has filler boards (15,16) connected to free board slots (13). In one embodiment, the filler boards (15) simulate the effect of circuit boards on airflow and act to evenly distribute the cooling air flow inside the computer cabinet (10) in order to provide improved cooling of the circuit boards. In another embodiment, the filler boards (16) block airflow between filler boards connected to adjacent board slots to direct more cooling airflow to any slots equipped with option circuit boards. The filler boards are made of electrically-conductive material (30) to absorb electromagnetic radiation emissions, and are covered with acoustically-absorbent material (33) to absorb sound emissions of the apparatus.