| 摘要 |
PURPOSE:To detect a scale from an input musical sound of complex tone constitution through simple hardware, and to specify the kind of a chord according to the detection result and generate an accompaniment part in real time. CONSTITUTION:A DSP 116 performs respective band-pass filter processes based upon pitch frequencies of respective scale sounds in the range of an acoustic signal, inputted form a microphone 112, etc., as center frequencies on a time- division basis and outputs envelope signals by the scale sounds to a CPU 101. The CPU 101 integrates the levels of the envelope signals by the scale sounds at timing of, for example, every 1/2 beat and selects a scale sound which is large in integral value, e.g. up to four sounds. Further, the CPU 101 generates a group of chord data from a group of chord constituent sounds of every 1/2 beat and generates an obbligato pattern from the variation pattern of a series of generated chord data. Then the CPU 101 instructs a musical sound generating circuit 108 to play an automatic accompaniment based upon the obbligato pattern. |
