CN112216260A

CN112216260A - Electronic erhu system

Info

Publication number: CN112216260A
Application number: CN202011084888.3A
Authority: CN
Inventors: 马小娟; 郭心雨; 樊璐瑶
Original assignee: North University of China
Current assignee: North University of China
Priority date: 2020-10-12
Filing date: 2020-10-12
Publication date: 2021-01-12

Abstract

The invention discloses an electronic urheen system, and belongs to the technical field of musical instruments. The system comprises: the system comprises a homologous substitution audio streaming system, a performance analysis system, a playing system and a tone library; the homologous substitution audio stream system is used for establishing models corresponding to different techniques of the urheen and sending the models to the performance analysis system; the performance analysis system is used for detecting the vibration signals of the urheen codes, determining the current performance information of the urheen according to the detected vibration signals and the model, and sending the performance information to the playing system; and the playing system is used for calling the wavetable in the tone library according to the performance information, synthesizing and playing the corresponding music by adopting a wavetable synthesis mode. The invention replaces the sound emitted by the urheen by the sound in the sound color library, so that the sound production mode is irrelevant to the material and is only relevant to the quality of the sound color library, thereby thoroughly getting rid of the dependence of the urheen on the material and greatly reducing the manufacturing cost of the electronic urheen.

Description

Electronic erhu system

Technical Field

The invention relates to the technical field of musical instruments, in particular to an electronic erhu system.

Background

The urheen, namely a two-stringed huqin, is a stringed instrument, has two strings, called "xi qin", also called "nan hu" and "buzz", is one of the main bowed stringed instruments (stringed instruments) in the chinese national musical instrument family, starts from the tang dynasty, has a history of more than one thousand years so far, and is a traditional chinese stringed instrument. The modern erhu sets strings in five degrees, belongs to a high-pitch range instrument in the urheen, and bowed string instruments in different shapes, such as a gaohu, a beijing opera, a banhu, two strings, a horn string and the like, are independently developed in various places according to required conditions.

The traditional urheen is used for generating sound by string vibration and amplifying the sound through resonance, so that the sound production mode of the urheen is related to materials. In the prior art, a violinist usually uses wood to make erhu, such as rosewood, ebony, winged wood, rosewood, red sandalwood, african safflower pear, african red sandalwood, etc., and also uses ivory, jade, plastic, etc. because of considerations other than acoustics. One end of the barrel is covered with snake skin, which is the source of unique timbre of the urheen, and some advanced urheens use the snake skin. That is to say, the sound quality of the traditional urheen is determined by the materials, the selection of the urheen materials has great influence on the body, and a good urheen needs expensive wood and is very high in cost. In addition, the electronic urheen in the prior art plays the music through detecting the vibration of the strings and amplifying the power of the vibration signal, and the dependence on materials is very large, so that the manufacturing cost of the urheen is high.

Disclosure of Invention

In order to get rid of dependence of the urheen on materials, the embodiment of the invention provides an electronic urheen system, which comprises: the system comprises a homologous substitution audio streaming system, a performance analysis system, a playing system and a tone library, wherein the tone library adopts a wave table synthesis technology;

the homologous substitution audio stream system is used for establishing models corresponding to different techniques of the urheen and sending the models to the performance analysis system;

the performance analysis system is used for detecting the vibration signals of the urheen codes, determining the current performance information of the urheen according to the detected vibration signals and the model, and sending the performance information to the playing system;

and the playing system is used for calling the wavetable in the tone library according to the performance information, and synthesizing and playing the corresponding music by adopting a wavetable synthesis mode.

Optionally, the homologous replacement audio streaming system is specifically configured to:

modeling an envelope curve in the sound of the urheen to obtain time domain models corresponding to different techniques of the urheen;

and converting the time domain model into a frequency domain model, and sending the frequency domain model to the performance analysis system.

Optionally, the performance analysis system includes a vibration detection and analysis module and a signal analysis module, both of which are electrically connected to the power supply, and the vibration detection and analysis module is wirelessly connected to the signal analysis module;

the vibration detection and analysis module is used for detecting vibration signals of the urheen code, performing A/D conversion to generate a sequence S (n), and sending the sequence S (n) to the signal analysis module;

the signal analysis module is used for performing discrete fast Fourier transform on the sequence S (n) to obtain a frequency domain function, determining parameters of the urheen vibration signals according to the frequency domain function, and determining the current performance information of the urheen according to the parameters and the model.

Optionally, the vibration detection and analysis module comprises a piezoelectric ceramic, a filter circuit and a controller,

the piezoelectric ceramic is arranged at the position of the urheen code, is connected with a charge amplifier and an operational amplifier and is connected to the filter, and is used for detecting a vibration signal of the urheen code, amplifying the vibration signal through the charge amplifier and the operational amplifier and then transmitting the vibration signal to the filter;

the filter is used for filtering clutter of the vibration signal and then sending the filtered vibration signal to the controller;

the controller is used for carrying out A/D conversion on the filtered vibration signals, generating the sequence S (n), and sending the sequence S (n) to the signal analysis module.

Optionally, the performance information includes a performance style, a performance dynamics and a performance pitch, and the signal analysis module is specifically configured to:

performing discrete fast Fourier transform on the sequence S (n) to obtain a frequency domain function of the vibration signal;

determining the fundamental rate, amplitude and amplitude-frequency change rule of the urheen vibration signal according to the frequency domain function;

and comparing the basic rate, the amplitude and the amplitude-frequency change rule with the model, determining a playing mode, playing strength and playing pitch, and sending the playing mode, the playing strength and the playing pitch to the playing system through the expanded MIDI protocol.

Optionally, before the invoking of the sound in the tone library according to the performance information and the synthesizing and playing of the corresponding music, the method further includes:

sampling the Erhu sound to obtain a plurality of sample sounds;

determining a frequency of each of the sample tones;

one sample sound in every two adjacent sample sounds is low-frequency, the other sample sound is high-frequency, the low-frequency sample sound is up-modulated to a plurality of intermediate frequencies between the low frequency and the high frequency through a variable speed pitch modulation algorithm, so that a plurality of sample sounds of the intermediate frequencies are obtained in addition, and an expanded tone library is formed.

Optionally, the tone library is specifically configured to:

sending an instruction to a wave table according to the performance information;

finding out corresponding sound information one by one from the table;

and sending the sound information to the playing system for synthesis playing.

Optionally, the storing the tone library on an SD card, and before the calling the sound in the tone library according to the performance information and synthesizing and playing the corresponding music, the method further includes:

inserting the SD card into computer equipment, downloading a corresponding tone library, and burning the tone library in the SD card;

and putting the SD card back into the electronic urheen system.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

it is worth pointing out that, the invention provides an electronic urheen system based on MIDI technology, which replaces the sound generated by the urheen by the sound in the sound color library, so that the sound generation mode is independent of the material, and only the quality of the sound color library is relevant, thereby completely getting rid of the dependence of the urheen on the material, and greatly reducing the manufacturing cost of the electronic urheen. Secondly, the MIDI tone library is expanded, more tones are inserted between adjacent notes on the basis of the twelve-tone equal temperament, namely, non-standard tones are added, so that the playing effect of the electronic urheen system is closer to that of a high-quality acoustic urheen, the tone quality is greatly improved, the adoption of the MIDI technology ensures the processing of special skills, the diversity of the sounds is increased, and the playing effect of the skill tracks is ensured. In addition, the price of the piezoelectric ceramic is relatively low, the piezoelectric ceramic is attached to the bridge to detect the vibration of the strings, the high cost of the vibration sensor can be avoided, and the manufacturing cost of the electronic urheen is further reduced. Moreover, the tone library can be stored in the SD card, so that each player can optimize the tone, and different tones can be downloaded, so that the tone library can meet the playing requirements of different players, and the SD card is simple and convenient.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a block diagram of an electronic erhu system according to an embodiment of the present invention;

fig. 2 is a schematic position diagram of a piezoelectric ceramic according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It is to be noted that, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The following describes in detail an electronic urheen virtual dulcimer system according to an embodiment of the present invention with reference to fig. 1 to 2.

Fig. 1 is a block diagram of an electronic erhu system according to an embodiment of the present invention. Referring to fig. 1, the system includes: the system comprises a homologous substitution audio stream system, a performance analysis system, a playing system and a tone library, wherein the tone library adopts a wave table synthesis technology; the homologous substitution audio stream system is used for establishing models corresponding to different techniques of the urheen and sending the models to the performance analysis system; the performance analysis system is used for detecting the vibration signals of the urheen codes, determining the current performance information of the urheen according to the detected vibration signals and the model, and sending the performance information to the playing system; and the playing system is used for calling the wavetable in the tone library according to the performance information, synthesizing and playing the corresponding music by adopting a wavetable synthesis mode.

It is to be noted that wave table synthesis is to sample the sound of the musical instrument, store it as a wave table file, send out the order to the wave table according to the music information recorded in the music file while replaying, find out the corresponding sound information one by one from the table, synthesize it by the microprocessor on the sound card or CPU of the PC system, play it out after processing. Wave table synthesis is often divided into soft and hard wave tables, depending on where the sample file is placed and processed by a dedicated microprocessor or CPU, now called "wave table" sound card, commonly called "OPL4", which also includes mixers, MIDI, etc. in addition to 16-bit recording and FM synthesizer for OPL 3.

Further, the homologous replacement audio streaming system is specifically configured to: and modeling an envelope curve in the sound of the urheen to obtain time domain models corresponding to different techniques of the urheen, converting the time domain models into frequency domain models, and sending the frequency domain models to a performance analysis system.

It should be noted that the sound of the urheen can be decomposed into a basic sound sequence a (n) and an envelope curve b (n), that is: s (n) ═ a (n) · b (n). Since the basic sound sequence a (n) is fixed, only the envelope curve b (n) needs to be modeled. The first three parts of the urheen sound are linear curves, the fourth part is damping attenuation, and the first three parts affecting the urheen sound characteristic are modeled, so that the first three parts are mainly modeled and are summarized as a function: and b (n) ═ k · x (n) + b, and the time domain models corresponding to different techniques of the two-stringed bowed instrument can be obtained by adjusting the values of k and b. Because the performance of the urheen needs real-time analysis, the time domain model of the envelope curve is converted into a frequency domain model: f (n) ═ f (x (n)).

Furthermore, the performance analysis system comprises a vibration detection analysis module and a signal analysis module, wherein the vibration detection analysis module and the signal analysis module are both electrically connected with the power supply, and the vibration detection analysis module is wirelessly connected with the signal analysis module;

and the signal analysis module is used for performing discrete fast Fourier transform on the sequence S (n) to obtain a frequency domain function, determining parameters of the urheen vibration signals according to the frequency domain function, and determining the current performance information of the urheen according to the parameters and the established model.

The Signal analysis module is composed of a DSP (Digital Signal Processing) and a driving circuit thereof, and is connected to a power supply for supplying voltage thereto to perform corresponding operations. The DSP processing is to use a computer or a special processing device to perform processing such as acquisition, transformation, filtering, estimation, enhancement, compression, identification, etc. on the signals in a digital form to obtain a signal form meeting the needs of people. Because all the timbres may not be stored in the timbre library, the DSP technology can be used for performing reverberation, length conversion and other processing on one or more timbres, so that the timbres required by synthesis can be obtained, and the corresponding music can be synthesized.

In addition, fourier transform is an important algorithm in the field of digital signal processing, and can convert a time domain signal, which is originally difficult to process, into a frequency domain signal (spectrum of the signal) which is easy to analyze. The discrete Fourier transform is to obtain the frequency spectrum function of a time continuous signal by utilizing the Fourier transform, or obtain the original time function by the inverse transform of the frequency spectrum function. Fast Fourier Transform (FFT), a general name of an efficient and fast calculation method for calculating Discrete Fourier Transform (DFT) by using a computer, is proposed in 1965 by j.w. kully and t.w. diagram base, and by using the algorithm, the number of multiplications required by the computer to calculate the discrete Fourier transform is greatly reduced, and particularly, the more the number of transformed sampling points N is, the more the calculation amount of the FFT algorithm is saved.

Further, the vibration detection analysis module comprises piezoelectric ceramics, a filter circuit and a controller.

Referring to fig. 2, the piezoelectric ceramics are arranged at the position of the urheen bridge, connected with a charge amplifier and an operational amplifier, and connected with a filter, and the invention also uses a thin wood plate to replace the snakeskin of the urheen, and the piezoelectric ceramics are stuck on the back of the thin wood plate opposite to the bridge. The piezoelectric ceramic is used for detecting a vibration signal of the urheen code, amplifying the vibration signal by a charge amplifier and an operational amplifier, and then transmitting the vibration signal to a filter;

the controller is used for carrying out A/D conversion on the filtered vibration signals to generate a sequence S (n) and sending the sequence S (n) to the signal analysis module.

It should be noted that the piezoelectric ceramic has a sensitive characteristic, and can convert an extremely weak mechanical vibration into an electrical signal, so that the piezoelectric ceramic disposed at the bridge can detect the vibration of the bridge and convert the vibration into the electrical signal, and the vibration of the strings can be simply and accurately detected through the piezoelectric ceramic. In addition, the price of the piezoelectric ceramics is relatively low, and the piezoelectric ceramics is used for detecting the vibration of the strings, so that the expensive cost of a vibration sensor can be avoided, and the manufacturing cost of the urheen is greatly reduced.

Further, the performance information includes performance mode, performance dynamics and performance pitch, and the signal analysis module is specifically used for:

carrying out discrete fast Fourier transform on the sequence S (n) to obtain a frequency domain function of the vibration signal;

and comparing the basic rate, the amplitude and the amplitude-frequency change rule with the established model, determining the playing mode, the playing strength and the playing pitch, and transmitting the playing mode, the playing strength and the playing pitch to the playing system through the expanded MIDI protocol.

It should be noted that, the MIDI instructions belong to binary files, which generally include file headers and data descriptions, and unlike waveform files, MIDI files do not sample music, but record each note of the music as a number, so that compared with waveform files, the files are much smaller and can meet the requirements of long-time music; the MIDI standard specifies the mixing and sonification of various tones, and these numbers can be resynthesized into music by an output device.

Furthermore, before calling the sound in the tone color library according to the performance information and synthesizing and playing the corresponding music, the tone color library is generated first, and the standard sound included in the tone color library is expanded to obtain the tone color library including the non-standard sound. Specifically, the method comprises the steps of firstly sampling a urheen sound to obtain a plurality of sample sounds, and determining the frequency of each sample sound; one sample sound in every two adjacent sample sounds is low-frequency, the other sample sound is high-frequency, and the low-frequency sample sound can be up-modulated to a plurality of intermediate frequencies between the low frequency and the high frequency through a variable speed pitch-shifting algorithm, so that a plurality of sample sounds of the intermediate frequencies are obtained in addition, and an expanded tone library is formed.

Note that in music, notes are set according to the twelve tone equal law, that is, frequencies with intervals between every two tones. For example, between note 1 and note 2, it is 440Hz to 460Hz, after sample tones 1 and 2 are obtained, 440Hz can be raised to intermediate frequencies of 441Hz, 442Hz, … …, 459Hz, etc. by a pitch-shifting algorithm, so as to obtain sample tones (i.e. non-standard tones) of a plurality of intermediate frequencies, and form an extended tone color library.

It is worth noting that MIDI technology is commonly used in electric pianos and electronic organs, and a great deal of expansion is being made to MIDI technology, which has gradually formed a series of technologies based on MIDI technology. However, because the MIDI design was originally designed for keyboard music, MIDI is only suitable for keyboard music and its application in string music is not considered. The MIDI represents high pitch with 126 tones, including all tones on the keyboard, but between two adjacent pitches there are a lot of sounds of consecutive tones, which cannot be represented by MIDI, and if the original MIDI technology is directly applied to an electronic urheen, it cannot represent the skills of urheen such as sliding, twisting and bowing. Therefore, the electronic urheen system provided by the invention expands the standard MIDI, and a plurality of sample tones with intermediate frequencies are inserted between the original two sample tones in the tone color library, thereby ensuring the continuity of the sound.

Furthermore, the envelope curve reflects the intensity of sound performance in different time periods, such as piano sound, which is initially loud and then fades out. Because the real-time playing dynamics of each player may be different, that is, playing modes with different dynamics may exist for the same tone, the tone color library can be inserted into the envelope curve to modify the envelope curve in real time, that is, the current playing dynamics can be modified in real time according to the actions of the user at different moments. Therefore, the playing dynamics is modified in real time, and the sound of the sample sound played by adopting all dynamics does not need to be stored in the tone color library, so that the storage space is reduced, and the continuity of the sound is further ensured.

Further, the tone library is specifically configured to: according to the performance information, an instruction is sent to the wave table, corresponding sound information is found out one by one from the table, and then the sound information is sent to a playing system for synthesis playing.

It should be noted that, the sound color library of the present invention is stored as a wave table file, when the sound color library is required to be called to replay music, an instruction can be issued to the wave table according to the determined performance information, corresponding sound information is found out one by one from the table, and the corresponding music is synthesized and played by the playing system in a wave table synthesis manner.

Further, a tone library is stored on the SD card; before calling the sound in the tone library according to the performance information and synthesizing and playing the corresponding music, the SD card can be inserted into the computer equipment, the corresponding tone library is downloaded and burned in the SD card; then the SD card is put back into the electronic urheen system, so that the subsequent playing system can send out an instruction to a tone library (wave table) according to the performance information, find out the corresponding sound information from the table one by one, synthesize and play the sound information, and the method is simple and convenient.

The complete use process of the electronic urheen system provided by the invention can be as follows:

before the electronic urheen system provided by the invention is used, the urheen sound is sampled and stored as a wave table file, and the wave table file is a tone library. In addition, models corresponding to different techniques of the urheen are established through a homologous replacement audio streaming system, so that the current performance information of the urheen can be determined according to the models.

When a player plays a bridge of the electronic urheen, the piezoelectric ceramics arranged at the bridge can detect a played vibration signal, the vibration signal is amplified by the charge amplifier and the operational amplifier and is transmitted to the filter for filtering, then the controller can perform A/D conversion on the filtered vibration signal to generate a sequence S (n), and the sequence S (n) is sent to the signal analysis module. The signal analysis module performs discrete fast Fourier transform on the sequence S (n) to obtain a frequency domain function of the vibration signal, then determines the base rate, amplitude and amplitude-frequency change rule of the urheen vibration signal according to the frequency domain function, compares the base rate, amplitude and amplitude-frequency change rule with a pre-established model to determine the playing mode, playing force and playing pitch, and sends the playing mode, playing force and playing pitch to the playing system through an expanded MIDI protocol. Finally, the playing system sends out an instruction to a tone library (i.e. a wave table) according to the performance information, finds out the corresponding sound information from the table one by one, and synthesizes and plays the sound information.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. An electronic erhu system, characterized in that the system comprises: the system comprises a homologous substitution audio streaming system, a performance analysis system, a playing system and a tone library, wherein the tone library adopts a wave table synthesis technology;

2. The electronic erhu system of claim 1, wherein the homologous replacement audio streaming system is specifically configured to:

3. The electronic erhu system as claimed in claim 1, wherein the performance analysis system comprises a vibration detection and analysis module and a signal analysis module, the vibration detection and analysis module and the signal analysis module are both electrically connected with a power supply, and the vibration detection and analysis module is wirelessly connected with the signal analysis module;

4. The electronic urheen system of claim 3, wherein the vibration detection analysis module comprises a piezoelectric ceramic, a filter circuit and a controller,

5. The electronic urheen system of claim 3, wherein the performance information includes performance style, performance dynamics and performance pitch, and the signal analysis module is specifically configured to:

6. The electronic urheen system of claim 1, wherein before the step of calling the sounds in the tone color library according to the performance information and synthesizing and playing the corresponding music, the method further comprises:

sampling the Erhu sound to obtain a plurality of sample sounds;

determining a frequency of each of the sample tones;

7. The electronic urheen system of claim 1, wherein the tone library is specifically configured to:

finding out corresponding sound information one by one from the table;

and sending the sound information to the playing system for synthesis playing.

8. The electronic urheen system of claim 1, wherein the tone color library is stored on an SD card, and further comprising, before the step of calling the sounds in the tone color library according to the performance information and synthesizing and playing the corresponding music:

and putting the SD card back into the electronic urheen system.