GB2171837A - Voice sensitive musical apparatus - Google Patents

Abstract

In musical apparatus, a vocal input causes a microphone (3) to produce an electrical signal, the fundamental frequency of which depends on the pitch of the vocal input. The electrical signal, in the embodiment shown, is passed to an envelope generator (13) to provide control outputs (14-17), further fixed outputs (25) being provided by circuit (24). The electrical signal is also passed to a phase locked loop (20) and divider chain (21) to generate signal outputs (22). Various of the outputs are selected by switch matrix (26) and passed to a signal generating circuit comprising a voltage-controlled filter (27) and a voltage-controlled amplifier (28). The signals therefrom are passed to a loudspeaker (31) which issues a musical output. <IMAGE>

Description

SPECIFICATION Voice sensitive musical apparatus The present invention relates to a voice sensitive musical apparatus or a component thereof. In one form, it enables the selection of a plurality of control channels or actions in response to a sound input, which actions to be selected being preferably the notes produced by a musical instrument, for example an electronic organ or synthesiser. In another form it may be incorporated with sound transducers to produce entirely novel instruments.

One object of the invention is to allow certain tone-deaf, handicapped or otherwise unmusical people to play music whereas they could not do so before. An alternative object is to provide a musical toy which can be played by children, however old.

According to one aspect of the present invention there is provided an apparatus comprising a transducer adapted to receive a vocal input and to give an electrical output signal the fundamental frequency of which depends on the pitch of the vocal input, and converter means to which said signal is applied and which are operative to provide at least one control signal in response to the signal received.

Preferably the signal from the transducer is filtered and clipped before it is supplied to the converter means.

The converter means may be a frequencyto-voltage converter the output of which is connected to an analogue-to-digital converter operative to decode the voltage signal so as to give an output at one of a plurality of outputs in dependence on the value of the voltage signal.

Alternatively the output of the frequency-tovoltage converter may be connected to a buffer amplifier so as to give a linear voltage output to an exponential converter so as to give a logarithmic voltage output.

In another aspect of the invention, there is provided a programme device which can be associated with an apparatus as set forth above and with a musical instrument, the programme device enabling a user to preselect a sequence ofchords to be played by the musical instrument and being operative to instruct the associated instrument to play the chords sequentially. The programming device may include a magnetic card reader.

The programme device may also include means for inhibiting the otherwise completely free choice of notes which the player can, through his vocal input, cause the associated instrument to produce.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 is a schematic block diagram of one embodiment of an apparatus for converting a vocal input into a signal; FIGURES 2 to 4 are similar diagrams of three further embodiments; FIGURE 5 is a schematic diagram of an embodiment of a musical instrument constructed in accordance with the invention, in association with a programme device also in accordance with the present invention; and FIGURE 6 is a schematic block diagram of another embodiment generating audible signals in response to vocal inputs.

Referring now to Figure 1 of the drawings, there is shown a mouthpiece 2 for receiving an audio input, generally a vocal sound emitted by the user of the device. Vocal inputs present some problems in detection of the fundamental frequency or pitch. Among other reasons, there is a wide variation of harmonic content of voice from person to person, there is difficulty in maintaining a consistently similar harmonic content over the whole frequency range of a person's voice and the harmonic content of the voice alters significantly with level or volume changes.

One method of overcoming the above difficulties and providing stable pitch detection, frequency control and/or keying from a vocal sound source input utilises a mechanical resonator 1 to provide standarised sound output in which the bulk of the individual qualities of voices of people using the device are eliminated. The sound output of the reasonator 1 is picked up by a suitable transducer 3 and converted into an electrical signal. However, the mechanical resonator 1 may be omitted in many applications of the apparatus, and the vocal input can be converted directly to an electrical signal by a suitable transducer. The electrical signal in this embodiment, however generated is supplied to a band-pass filter 4, and thence to a Schmitt trigger 5 where the filtered signal is clipped again to emphasise the fundamental pitch of the vocal input.

The frequency range of the detection circuits is limited to about three octaves to cover only the average person's maximum pitch ranges. Frequencies outside of this range are heavily attenuated to minimise spurious responses caused by harmonics.

The apparatus shown in Figure 1 is capable of driving either electronic organ type keyboards or synthesisers (normally linear or logarithmic controlvoltage types). The system may, of course be embodied in a self-contained musical instrument.

The clipped signal at the output of Schmitt trigger 5 is fed to a frequency-to-voltage converter 6 which accordingly supplies at its output a voltage the amplitude of which is dependent upon the pitch of the audio input. This voltage can be utilised in a number of ways.

In order to control an electronic keyboard instrument, the output of the converter 6 is fed to an analogue-to-digital converter 7 con nected to a decoder 8 having a number of outputs corresponding to the number of keys of the instrument. In response to the received voltage the converter 7 and decoder 8 generate an output signal on a selected one of the outputs of the decoder in response to the amplitude of the received voltage, and thus on the pitch of the vocal input. Thus as the user of the apparatus changes his vocal pitch the keyboard instrument will be appropriately keyed.

Alternatively, the output of the frequency-tovoltage converter 6 can be supplied to either a buffer amplifier 9 so as to give a linear voltage output or an exponential converter 10 so as to give a logarithmic voltage output.

The output of the buffer amplifier 9 can be used to control the audio output of a synthesiser of the kind which responds to a linear control voltage, and the output of the exponential converter can be used to control a logarithmic control voltage type synthesiser.

For example, the output voltage could be scaled so as to give one volt per octave.

The output of the band-pass filter 4 is also taken via a variable resistance to a voltage detection amplifier 11 which provides a "keyon-trigger" output, that is, an output only occurs when the input level exceeds a threshold.

Thus the voltage detection amplifier 11 "senses" the audio input level when the apparatus is first used and may be used to control the beginning and the ending of the sound envelopes generated by the instrument to which the apparatus is connected. Furthermore, the sensed audio input level can be used to control the output sound level. This would enable a user of the device to have total control by way of vocal input alone.

If used, the resonator 1 may be of any suitable type and may, for example, have a diaphragm which vibrates in sympathy with the input sound source and which is associated with a suitable electromechanical transducer.

Referring now to Figure 2, this shows an alternative method of providing selection between a plurality of outputs by means of the pitch of an audio input which will normally be a vocal input.

As in the embodiment of Figure 1, a vocal input can be applied to a mouthpiece 2 associated with a transducer 3 which provides an electrical audio signal. However, in the present embodiment the audio signal is supplied to an array of parallel band-pass filters 40 each one of which is tuned to respond to a particular note or narrow range of frequencies. The outputs of the band-pass filters 40 are in turn connected to an array 50 of associated level sensitive trigger switches, each switch being in turn associated with an individual output line. The output lines are generally indicated at 51 and each is connected to an individual tone generator.Accordingly when a user of the device sings, whistles or hums a note at a particular pitch, one of the band-pass filters 40 tuned to that pitch will cause its associated level sensitive switch in the array 50 to provide an output on the appropriate line 51 so as to cause the tone generator attached to that output line to generate a note of the same pitch and duration.

Referring now to Figure 3 of the accompanying drawings, this shows yet another embodiment in which a vocal input to a transudcer 3 provides an electrical audio signal. In this embodiment the signal is applied to a sampler circuit 60 which in turn gives an output to a Fourier analyser 61, the sampler 60 and Fourier analyser 61 being connected to a clock circuit 62. The use of a Fourier analyser to recognise frequencies very quickly and in a very short time interval using sampling methods is well known. The output of the Fourier analyser 61 is the fundamental frequency of its input signal without the harmonics and this fundamental frequency can then be used in manners similar to those disclosed with reference to Figure 1.

The embodiment of Figure 4 is a variant of the embodiment of Figure 1 in which the output of the Schmitt trigger 5 is taken to a phase-locked loop circuit including a phaselocked loop 67 and an oscillator 68. This circuit produces a voltage output which represents an input frequency and this output is taken, to an analogue-to-digital converter 7 and to a decoder 8, as in the Figure 1 embodiment. However, the output of the phaselocked loop circuit 66 could equally well be taken to a buffer amplifier so as to give linear voltage output or to an exponential converter so as to give a logarithmic voltage output.

The embodiment of Figure 5 shows a musical instrument controlled solely by vocal input in a manner similar to the embodiments already described but in association with a programme device by means of which the user of the instrument can selectively enhance or restrict the ultimate performance of the instrument. Thus, the apparatus comprises a mouthpiece 2 and a transducer 3 for providing an electrical audio signal which is supplied to a circuit generally indicated at 100 and which can take one of the forms described with reference to Figures 1 to 4 in order to provide a control signal on one of a plurality of channels in accordance with the pitch of the vocal input. These channels are connected to a gating circuit 101 in turn providing output on a similar number of channels to an associated set of tone generators 102. The outputs of the tone generators are in turn connected to a transducer 103. The gating circuit 101 and tone generators 102 are also controlled by a programme device in the form of a programme control circuit 104 which in the present embodiment is adapted to read magnetic cards.

Thus, by means of one type of magnetic card the user of the instrument can preprogramme the programme device with a chord sequence and can also programme the device so that the chords will be played sequentially at any preset speed and with whatever rhythmic pattern and tonal quality he chooses. Thus, in the absence of a vocal input to the mouthpiece 2 the programme device 104 can cause the tone generators 102 to drive the transducer 103 to provide selected sequences of chords.

However the fundamental aim of this embodiment is to enable a user of the device to supplement the sounds generated by his own vocal input with the programme of chords in the programme device so as to provide a composite output. It will of course also be appreciated that the programme device need not necessarily incorporate a magnetic card reader but any other suitable form of memory store can be used.

A second use of the programme device is to provide a means of restricting the otherwise free choice of notes which the player can, through humming, whistling or singing cause the transducer 103 to produce. The exact nature of these restrictions are not fundamental to the present invention but it will be realised that certain notes should not normally be produced when, for example, they are dissonant with those in the chord accompaniment. Thus, the programme device 104 can be programmed so that any note applied to the mouthpiece 2 which is not in the chord triad being played at that time will be blocked in response to the programme.

Alternatively, the programme device could be programmed so that any note supplied to the mouthpiece 2 which is within a musical "second" of the root note of the chord, that is within a stated frequency ratio, can be gated out by the gating circuit 101 so that it is not reproduced by the transducer 103.

This second, restrictive mode of use of the programmer device can also, alternatively, provide a means of augmenting or enhancing the notes being whistled, hummed or sung by the player in accordance with enhancement rules appropriate to the type of music being played.

Referring now to Figure 6 there is shown a block circuit diagram for another embodiment of the invention in which a vocal input will generate a varying musical output. As before, an electrical signal generated in response to a vocal input by a suitable transducer 3 is passed to a band pass filter. Optionally the band pass filter may be replaced for the sake of cheapness by a low pass filter 4 to remove harmonics. The signal is then passed to a preamplification stage 12.

One output is fed to an envelope generator 13 which has four outputs 14 to 17. A first output 14 is fed directly by the alternating output from preamplifier 12 to give a varying control waveform. Another output of the preamplifier 12 is fed to a trigger circuit 18 comprising a rectifier and comparator. The output of the trigger circuit 18 is also fed to envelope generator 13 where it is used to produce three control waveforms at outputs 15,16 and 17. The waveforms are shown diagrammatically adjacent the respective output.

A further output of the preamplifier 12 leads to a clipping circuit 19 and thence to a phase locked loop circuit 20. This circuit feeds a divider chain 21 which provides a number of harmonically related signal outputs 22, nominally from 1 foot to 128 feet for example.

The response time of the phase locked loop circuit 20 can be varied by switch selection to give slow tracking or complete track inhibition.

This is achieved by circuit 23.

One or other of the signal output 22 may be switch selected to give a feedback connection to the phase locked loop circuit 20 and thereby enable a transposition in its output, i.e. an octave shifting.

Shown separately as 24 is a circuit giving three or more control outputs 25 at fixed voltages.

All of the control outputs 14-17, and 25 and the signal outputs 22 pass to a switching matrix 26 where one or more of each type is selected by manual switching. The signal output from the matrix 26 passes to a voltage control filter 27 and thence to a voltage control amplifier 28. At each of these stages, the signal may be controlled by a control output of the switching matrix. The control output comprises any one or more of: the outputs of the envelope generator 13; the harmonic signal outputs (which can be used as a control); or the fixed voltage level outputs 25. The resonance of the voltage control filter 27 can also be selected by the switching matrix 26 and the signal controlling this function is shown diagrammatically as 29.

Finally the controlled signal is passed to an amplifier 30 and to a loudspeaker 31, from which a musical signal is emitted.

In the preferred embodiment of the circuit of Figure 6, eight switches may be manually operated to give eight types of sound from the loudspeaker 31. In one form each sound type may be that of a particular musical instrument.

In another form the sounds which could be generated may be totally electronic.

The switching at the matrix 26 for the various sounds uses mainly choices of the signal input to filter 27, the filter 27 control and the amplifier 28 control. For certain sounds, however, the matrix may switch the filter resonance on or off or may inhibit or slow the tracking time of the phase locked loop circuit 20.

It will thus be seen that there has been described an apparatus which can be played by anyone who can sing, hum, whistle or make any other sound in a fashion and style which that person would normally employ when making the relevant sound.

The particular tonal quality of the instru ment's sound output can be selected at will by the choice of synthesised tonal content from within the instrument, or elsewhere.

Furthermore it will also be appreciated that should an apparatus embodying the invention, for example of the kind described with regard to Figure 1 of the accompanying drawings, be associated with a separate musical instrument, it would be possible for the instrument to be played independently of the apparatus. Thus a keyboard performer could accompany himself or a colleague in playing a "duet".

Finally, it will also be appreciated that with any of the embodiments described which incorporate tone generators it is not essential for them to generate a note of the same pitch as the vocal input. Instead there could be some preselected relationship between the pitch of the audio input and the audible output.

All the circuits described above may be modified from the form shown using custom chip technology using digital techniques to give similar results.

Claims (15)

1. A musical apparatus comprising a first transducer means adapted to receive a vocal input and to give an electrical output signal the fundamental frequency of which depends on the pitch of the vocal input, converter means to which said signal is applied and which are operative to provide at least one control signal in response to the signal received, means to produce second electrical output signals in response either to said received signal and/or to said at least one control signal, and second transducer means adapted to give a musical output as a function of said second signals.

2. A musical apparatus as claimed in claim 1, further comprising switch means whereby predetermined combinations of received signal and/or said at least one control signal may be selected to produce a different electrical signal to give a different type of musical output.

3. A musical apparatus as claimed in either claim 1 or claim 2, further comprising one or more additional control signals at a or each at a different fixed voltage.

4. A musical apparatus as claimed in any one of the preceding claims, wherein the converter means comprises an envelope generator.

5. A musical apparatus as claimed in any of the preceding claims, wherein the signals received from the first transducer means are fed to the signal producing means via a phase locked loop circuit and divider chain.

6. A musical apparatus as claimed in claim 1, wherein said second transducer means comprises the music generating circuits of an existing electronic musical instrument.

7. A musical apparatus as claimed in claim 6, wherein a plurality of control signals are provided and each control signal actuates a predetermined output of the musical instrument.

8. A musical apparatus as claimed in either claim 1 or claim 2, wherein the means to produce the second electrical output signals comprises memory means in which is stored at least one preselected signal, each second output signal corresponding to a respective preselected signal or combination thereof, and each being produced in response to a received signal and/or control signal.

9. A musical apparatus-as claimed in claim 8, wherein the converter means comprises an analog to digital converter and said at least one control signal is in digital form.

10. A musical apparatus as claimed in claim 9, in which the at least one preselected signal is stored in digital form.

11. A musical apparatus as claimed in claim 10, further comprising a digital to analog converter to receive said second signals in digital form and to transmit them in analog form to said second transducer means.

12. A musical apparatus as claimed in any one of the preceding claims, in which the signal from the first transducer means is filtered and/or clipped before it is received by the converter means.

13. A musical apparatus as claimed in any one of the preceding claims, further comprising a programme device to enable the user to preselect a sequence of chords to be played and being operative to instruct said second transducer means to play the chords sequentially.

14. A musical apparatus as claimed in claim 13, wherein the programme device further includes means for inhibiting the otherwise completely free choice of notes which may be produced.

15. A musical apparatus substantially as described herein with reference to any one of the Figures of the accompanying drawings.