Abstract: A method of (and apparatus for) extending the useful dynamic range of an audio reproduction system. An input acoustic signal in the audible range is transduced to form an analog electric signal which is amplified along parallel paths to gain levels g.sub.1 and g.sub.2 (where g.sub.2 >g.sub.1), the amplified signals being sampled to provide two binary digital signals. The analog signal consists of a high amplitude portion and a low amplitude portion. The two binary digital signals are processed by a computer which provides a first binary output and a second binary output, the first binary output being a digital representation of the sequential samples of the audio signal taken at the respective gain setting g.sub.1 or g.sub.2. More precisely, the first binary digital output is a composite binary digital waveform consisting of a high amplitude portion at gain setting g.sub.1, a low amplitude portion at gain setting g.sub.2 and a transition or cross-fade portion therebetween.

Abstract: A pulse generator for outputting a train of electric pulses with a controllably constant period (i.e., the reciprocal of pulse rate) between pulses of the pulse train. The generator includes electrical circuitry which produces an internal train of pulses some of whose periods vary an unacceptable amount from one another. Further, modifying circuitry is connected to receive each pulse of the internal train of pulses, the further circuitry being operable to modify the period of each pulse, when necessary, to an acceptable period with respect to the immediately preceding pulse.

Abstract: Apparatus and method for generating complex sounds having a more natural and agreeable quality wherein fundamental and higher order components may be uniquely and independently controlled to inexact integer relationships.

Abstract: A musical note oscillator producing notes at musical intervals having high resolution and high frequency stability achieved with an economy of components and control signals. The oscillator may be operated to provide multiple notes simultaneously and independently; and it is described in the context of a musical instrument.

Abstract: The disclosure describes improved apparatus for sampling a digitally-stored waveshape only at a rate 2.sup.N times the fundamental frequency of a note synthesized, where N is an integer. The apparatus includes a digital memory for storing a digital representation of the waveshape. A top octave synthesizer produces clock pulses at a rate 2.sup.N times the fundamental frequency of a desired note. An octave oscillator generates addresses for the digital memory in response to at least some of the clock pulses depending on the octave in which the desired note is located. A digital-to-analog converter converts the output from the digital memory into an analog signal suitable for sound production.

Abstract: The disclosure describes improved apparatus for synthesizing an audible note from its volume, attack-decay envelope and waveshape characteristics. By employing multiplying analog-to-digital converters, the characteristics can be rapidly generated and combined in real time, thereby enabling the use of the synthesis in performing instruments.

Abstract: The disclosure describes an improved digital oscillator for use in an electronic musical system capable of converting electrical tone signals into corresponding sound waves. The oscillator includes an adder, accumulator and multiplexer for selectively transmitting either a divisor number or increment number to the adder. The oscillator cyclically performs incrementing operations by using the increment number over a variable range established by the divisor number at the beginning of each cycle. When the modulus of the adder is exceeded, the adder generates a carry pulse and a remainder. The divisor is then added to the remainder before the incrementing operations begin again. A digital calculator automatically calculates the proper values of the increment and divisor numbers so that the carry pulses occur at a predetermined frequency.