Abstract: Apparatus and method for echo cancellation that incorporate a psychoacoustic model in determining the necessity to update compensator coefficients for the generation of artificial echoes for echo cancellation. The method includes the steps of dividing an audio signal having at least one echo into a plurality of subbands. For each of the plurality of subbands, the echo is reduced based on a variable coefficient transfer function to produce a compensated subband. The signal level of the compensated subband is then compared to a threshold value on a psychoacoustic model curve at a corresponding subband frequency. If the signal level of the compensated subband is greater than the threshold value, the coefficients of the transfer function are updated. Conversely, if the signal level of the compensated subband is less than or equal to the threshold value, the coefficients of the transfer function are not updated.

Abstract: An improved artificial neural network for use in speech recognition is disclosed. It comprises an input layer, a hidden layer, and an output layer, each of these layers consisting of a plurality of nodal points. A set of first weighting coefficients are used between the input layer and the hidden layer which are functions of at least one of the nodal points in the hidden layer and at least one of the nodal points in the input layer; whereas, a set of second weighting coefficients, which are functions of time and at least one of the nodal points in the output, are used to correlate between the hidden layer and output layer. In a preferred embodiment, the first weighting coefficients are calculated using the following formula: ##EQU1## i is the index for nodal point in the input layer and a.sub.j, b.sub.j, and c.sub.

Abstract: A method and apparatus for alleviating asthmatic attacks minimizes heat and water loss in the respiratory tract of the asthma sufferer. A portable embodiment of the apparatus includes an elongated tube having a fibrous material dispersed around the inner surface for holding water, a heating filament cylindrically coiled against the fibrous material and interconnected with a battery attached to the sufferer, and fiber wrapped around the filament for conveying the water located in the fibrous material to the surface of the filament for evaporation. The method for alleviating asthmatic attacks includes the steps of heating and evaporating water, heating the atmospheric air, and inspiring the heated atmospheric air and vaporized water.