An image display device which provides an enlarged main display image together with an environmental image disposed at its periphery; which is provided with a circumstances-detecting unit for detecting the operating conditions of the image display device and an image-changing unit for varying the environmental image according to parameters detected by the circumstances-detecting unit. The circumstances-detecting means detects the quantity or brightness of light inside or outside the display device and the sound volume of the display or surrounding sound outside the display device. The image-changing unit varies a light quantity and color tone of an environmental image of the display device according to the detected light quantity or brightness, or according to the detected sound volume or surrounding sound.

A CPU 21 sequentially changes over plural music pieces and reproduces the same by a program processing. Upon the changeover of the music piece, the volume of the tone signal that is being generated at each tone generating channel in a tone generating circuit 14 is gradually decreased, whereby the tone signal is finally faded out. The volume decreasing speed in this case is such that the higher the priority order of the performance data is, the slower the speed is. The generation of a tone signal based upon performance data of next music piece data is assigned one after another from a tone generating channel wherein a fade-out has been completed. The volume of the assigned tone signal is controlled so as to gradually increased, whereby the tone signal is faded in. In this case, the assignment of the generation of the tone signal based upon the performance data of the next music piece is made earlier, as the order of priority of the performance data is higher. A first music piece and second music piece can be naturally changed over and reproduced as cross-faded without preparing plural tone generating circuit systems.

A method for determining the intensity value of a sound begins by determining if a listener location is within one of an ambient ellipse region and a localized ellipse region, the ambient ellipse region and the localized ellipse region sharing a common focus at an origin of the sound and sharing a common medial axis. The intensity value of the sound is set to an ambient intensity value when the listener location is within the ambient ellipse region. The intensity value of the sound is set to a localized intensity value when the listener location is within the localized ellipse region, and the intensity value of the sound is set to zero when the listener location is not within the localized ellipse region or the ambient ellipse region.

System and method for creating a Doppler Effect signal in a virtual reality environment. A host produces: (1) an audio signal indicative of sound produced by a sound source, (2) a first set of signals indicative of a velocity of the sound source and an observer of the sound source, and (3) a second set of signals indicative of a position of the sound source and the observer. An interpolator interpolates the audio signal and generates an interpolation signal. A Doppler engine receives the first and second sets of signals and generates a decimation factor signal. A decimator filter, receives the interpolation signal and the decimation factor signal and generates a decimation signal. The decimation signal is a digital representation of said Doppler Effect signal and can be converted to an analog signal for broadcast to a listener.

This invention describes the use of dynamic sound source and listener position (DSSLP) based audio rendering to achieve high quality audio effects using only a moderate amount of increased audio processing. Instead of modeling the audio system based on sound and listener position only, the properties that determine the final sound are determined by the change in listener relative position from the current state and last state. This storage of the previous state allows for the calculation of audio effects generated by change in relative position between all sound sources and listener positions.