Automatic chord type and root note detector
AssigneeKawai Musical Instruments Mfg. Co., Ltd.
InventorsRalph Deutsch, Leslie J. Deutsch
Life of this patent
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Abstract
In an electrical keyboard musical instrument apparatus is provided for automatically selecting one of a library of chord types which is closest to a chord played on the instrument. The closest decision is made by processing the actuated keyswitch data by a set of matched filters each of which corresponds to a member of the library of chord types. The chord type decision is made to correspond to the matched filter producing the maximum output response. The selection between chord types yielding equal responses is resolved by priority logic based upon the frequency of chord usage. A root note is chosen for each selected chord type.
Claims11
Apparatus for selecting a musical chord type and its root note from a set of preselected musical chord types in a musical instrument having a keyboard with a plurality of key switches comprising:
- a clock providing a sequence of timing signals,
- a status memory means for storing data corresponding to actuated note switches in said plurality of key switches,
- a first memory means for storing data to be thereafter read out,
- a transfer means whereby data is read from said status memory and stored in said first memory,
- a second memory means for storing a plurality of transfer functions each corresponding to a musical chord type,
- a correlation evaluation means responsive to selected members of said plurality of transfer functions and responsive to data accessed from said first memory wherein a plurality of correlation numbers are generated,
- a third memory means wherein a correlation number is stored to be thereafter read out,
- a comparison means for comparing the magnitude of each of said plurality of correlation numbers with the correlation number stored in said third memory means wherein a correlation number having the maximum magnitude value is selected and stored in said third memory means, and
- a selection means responsive to said timing signals and said correlation number having a maximum magnitude value wherein a selection is made of a musical chord type from said preselected musical chord types and a selection is made of a corresponding root note.
A musical instrument having a keyboard with a multiplicity of keyswitches in which apparatus for selecting the closest musical chord type and its root note corresponding to actuated keyswitches comprises;
- a master clock means for generating a sequence of timing signals and a start signal corresponding to an initial timing signal,
- keyswitch connection circuitry whereby said multiplicity of keyswitches are electrically connected in parallel octaves,
- a status memory for storing the state of said keyswitch connection circuitry,
- a correlation memory means for storing data,
- a transfer means responsive to said start signal whereby data is transferred from said status memory to said correlation memory means,
- a transfer function memory means storing a plurality of matched filters each of which corresponds to a musical chord type,
- a first memory addressing means responsive to said master clock means whereby a matched filter is selected from said transfer function memory means,
- a matched filter processor means wherein data stored in said correlation memory means is processed by each of said selected matched filter thereby generating a plurality of correlation numbers, and
- a decision means responsive to said plurality of correlation numbers wherein a selection is made of the matched filter which causes the generation of a correlation number having a maximum value.
Dependencies are inferred from the claim text.