A method and apparatus for electrically producing musical sounds wherein a cavity resonator is formed by a hollow body defining a cavity having a constant configuration with a small opening communicating with the oral cavity of the mouth of a player and a change in the size of the oral cavity changes the resonant frequency and thereby the fundamental frequency of the sound produced. A vibrating cone in a closed chamber produces sound waves in the cavity resonator. An electric amplifier is driven by electric oscillations corresponding to monitored sound energy from the cavity resonator and the amplified oscillations are coupled back to the vibrating member to sustain the motion of the vibrating member. In one form, a coil on the vibrating cone and moving therewith is wrapped on a portion of a magnet producing a back emf to monitor the sound waves in the cavity resonator and also convert the amplified electric oscillations received from the electric amplifier to a physical oscillatory force to drive the vibrating cone. In another form a second sensing coil is mounted on the vibrating cone to move therewith and is inductively coupled to the first coil and magnet to monitor the sound energy. A pressure sensitive volume control facilitates control of the amplitude of the sound output with breath pressure. A range multiplier provides a three octave sound range. In yet further forms, a microphone may be mounted either in a closed chamber part of the cavity resonator opposite the mouthpiece or in a chamber portion of the cavity resonator adjacent and in communication with the mouthpiece to monitor the sound waves therein and provide corresponding electric oscillations that will drive the electric amplifier.
A sound reproducing system utilizes motional feedback and velocity-frequency equalization to reduce loud speaker distortion. The system substantially comprises a frequency equalizer-power amplifier combination which is jointly responsive to the input source signal and to a velocity feedback equalizer; the loud speaker structure which is responsive to the frequency equalizer-power amplifier combination; a cone motion sensing structure which is responsive to the motion of the loud speaker cone; an auxiliary amplifier which is responsive to the cone motion sensing structure; and the velocity feedback equalizer which is responsive to the auxiliary amplifier. Features of the present invention are that: the velocity shaped signal from the velocity feedback equalizer is degeneratively applied to the frequency equalizer-power amplifier combination which, in turn, forces the loud speaker to respond linearly to the input source signal and thereby provide a uniform sound energy output; the velocity-frequency equalization effect is limited to that frequency range over which the loud speaker cone operates substantially as a rigid member; the velocity feedback equalizer loss characteristic exhibits a positive slope over the low frequency and rigid member operating frequency range of the cone, and a zero slope over the high frequency range of the cone; the frequency equalizer loss characteristic exhibits a zero slope over the low frequency range of the cone, a positive slope over the rigid member operating frequency range of the cone, and a zero slope over the high frequency range of the cone; and the power amplifier gain characteristic exhibits a zero slope over the low frequency range of the cone, a negative slope over the rigid member operating frequency range of the cone, and a zero slope over the high frequency range of the cone. An advantage of the present invention is that it allows use of relatively small loud speakers and loud speaker enclosures.
A sound reproducing system utilizes motional feedback and an integrated magnetic structure to reduce loud speaker distortion. The loud speaker structure of such system comprises a main electromagnetic structure and a cone motion sensing structure. The main electromagnetic structure includes a cup-shaped cylindrical iron outer pole piece, a solid cylindrical permanent magnet, a solid cylindrical iron inner pole piece, a main voice coil, a thin cylindrical bobbin, a cone, a speaker frame, and flexible webs. The cone motion sensing structure includes a hollow cylindrical iron outer sleeve, a hollow cylindrical copper outer sleeve, a disc-shaped non-magnetic support, a hollow cylindrical copper inner sleeve, a solid cylindrical iron rod, a feedback coil, a thin feedback bobbin, and a conical member connecting the feedback bobbin to the voice coil bobbin. A stability control network is connected to the feedback coil for suppressing any supersonic transmission peaks appearing in the motional feedback signal. A feature of the present invention is that: the cone motion sensing structure utilizes the stray magnetic field of the main electromagnetic structure to provide the motional feedback signal which is functionally related to axial cone velocity, which motional feedback signal is fed directly to the stability control network as aforementioned. An advantage of the present invention is that it allows use of smaller loud speakers and loud speaker enclosures.
An electronic musical instrument providing continuous cybernetic tone finding controlled by functions of the human mouth. The instrument includes a mouthpiece into which air is to be blown from the mouth of a player having a measuring apparatus at least partially mounted therein. The measuring apparatus includes an arrangement for producing a pitch determining signal representing a measure of the mouth cavity of the player and a volume determining signal representing the velocity or pressure of the air blown into the mouthpiece. Tone generating apparatus is provided for generating a tone signal whose frequency varies with the level of a control signal applied thereto with a control signal being applied to the tone generating apparatus in accordance with the pitch determining signal and having a level representing a measure of the mouth cavity of the player. Another control signal in accordance with the volume determining signal serves for controlling the output of the tone generating apparatus with the output being converted to sound.
In an apparatus for assisting play of a wind instrument, an actuator is attached to the wind instrument for vibrating a portion of the wind instrument so as to assist play of the wind instrument. A microphone receives a vibration of a sound generated by the wind instrument and generates a vibration signal representing the vibration of the sound. A breath pressure sensor detects a pressure of a breath that is blown into the wind instrument during the play thereof, and generates a breath pressure signal corresponding to the detected pressure of the breath. A controller generates a control signal corresponding to the product of an inverse value of an envelope of the vibration signal and a value of the breath pressure signal. A variable gain amplifier amplifies the vibration signal with a variable gain which varies in response to the control signal so that an output signal of the variable gain amplifier is provided to enable the excitation part to vibrate the portion of the wind instrument.
A sound reproducing system utilizes motional feedback and an improved integrated magnetic structure for reducing loudspeaker distortion; for reducing acoustic coupling between the radiated sound energy output and the cone motion sensing structure thereby reducing unwanted feedback signals; and for reducing obstruction of the radiated sound energy output by the cone motion sensing structure thereby minimizing undesirable alteration of the radiated tonal quality. The loudspeaker includes a cone, a frame, and flexible webs. The main electromagnetic structure includes a rear cylindrical iron pole piece, an annular cylindrical permanent magnet, an inner annular cylindrical iron pole piece, a main voice coil bobbin, a main voice coil, and a front annular cylindrical iron pole piece. The cone motion sensing structure includes a front annular copper disc, a rear cylindrical non-magnetic support member, an annular cylindrical copper sleeve, a cylindrical iron rod, a feedback sensing coil, a feedback sensing coil bobbin, and a feedback sensing coil bobbin support member. The associated circuitry includes a stability control network, a velocity equalizer, and a frequency equalizer. A feature of the present invention is that: the cone motion sensing structure utilizes the stray magnetic field of the main electromagnetic structure to provide the motional feedback signal which is functionally related to axial cone velocity, which motional feedback signal is fed to the stability control network. An advantage of the present invention is that it allows use of smaller loudspeakers and smaller loudspeaker enclosures.
