Objective Classification of Hindustani Ragas

CONTENTS

PREFACE

1 INTRODUCTION
1.1 Background and motivation
1.2 Unique characteristic of Indian music
1.3 Characteristic of Music
1.4 Characteristic of Ragas
1.5 Features for classification
1.6 Objective of the book
1.7 Outline of the book

2 LITERATURE SURVEY
2.1 Introduction

3 STUDY OF ARTIST BEHAVIOUR FROM RAGA PERFORMANCE
3.1 Introduction
3.2 Mel frequency cepstral co-efficients
3.3 Statistical parametrization
3.4 Analysis and Results
3.5 Music classification
3.6 confusion matrix
3.7 Summary

4 COMPARISON BETWEEN RESTFUL AND RESTLESS RAGAS USING BASIC STATISTICAL FEATURES
4.1 Introduction
4.2 Research methodology
4.3 Experimental results
4.4 pitch transition
4.5 Analysis of transitory and non-transitory frequency movements between Notes
4.6 Summary

5 COMPARISON BETWEEN RESTFUL AND RESTLESS RAGAS USING ADVACED STATISTICAL FEATURES
5.1 Introduction
5.2 Research Methodology
5.3 Experimental Result
5.3.1 Modeling the Pilu and Todi Raga performance statistically
5.3.2 Single Exponential Smoothing for raga Todi gives a bad fit
5.3.3 Single Exponential Smoothing for raga Pilu gives a comparatively better fit.
5.4 Results and Discussion
5.5 Summary

6 STATISTICAL MODELING OF RAGA TODI PERFORMANCE
6.1 Introduction
6.1.1 Indian Classical Music
6.1.2 Musical features of raga Todi
6.2 Double exponential smoothing
6.2.1 Model equation
6.2.2 Forecasts
6.3 Experimental Result
6.4. Discussion
6.5. Summary

7 STATISTICAL STUDY OF MUSIC EMOTION
7.1 Introduction
7.2 Research methodology
7.3 Statistical parameterization
7.4 Experimental Results
7.5 Summary

8 CONCLUDING REMARKS

BIBLIOGRAPHY

PREFACE

With the development of technology in multimedia large amount of digital music is available on the internet and on personal devices. People are listening to the music of their choice for enjoyment. To listen to the music of their choice listeners have to search the music from a large database available on the internet by song title, composer, performer, mood (e.g. happy or sad song) and culture specific tags. In order to make their collections easily accessible to the people, music libraries need to classify music by genre, instrumentation, tempo and mood etc. For structuring and organizing large music files on the internet and make the desired music easily accessible to the consumer, important features of music signal are calculated so that music files can be categorized into different group such as genre, artists, style, emotion etc. The acoustic features of music signal are pitch, timbre, rhythm and melody [1-3]. Extraction of relevant information from the sample data in compact form is called features extraction [4-7].

Indian classical music can be categorized into two forms as Hindustani music and Carnatic music. Raga is the nucleus of both these forms. Raga is a melodic structure in which the musical notes are arranged in an unique way such that the notes follow either an ascending or descending pattern and typical note phrases when the raga is rendered by artists and have melody and rhythm in the raga piece so that a certain passion is generated by performer in the concert [8-12].

Indian music is monophonic (single melody line) in nature while western music can be polyphonic (multiple melody lines), consistent or a combination of both. Indian Classical Music concentrates on melody and rhythm.

Indian Classical Music, and indeed music universally, is built on the foundation of the seven basic swaras named as shadja, rishabh, gandhar, madhyam, pancham, dhaivat and nishad, and represented as Sa, Ri , Ga, Ma, Pa, Dha, and Ni. Sa is the note of origin called the tonic and rest of the notes are arranged accordingly.

It is a challenging issue to train a machine to identify the ragas in Indian music. The challenges can be minimized by finding the structure in a raga which can be easily captured. For instance, the most prominent swara used in a raga can be determine by measuring number of occurrences and the extent of each swara in a raga sung by the artist [12]. This may give the intuition into the set of notes and their repetition in a raga, thereby benefitting in recognition. Secondly, by finding Gamakas and Pakads used in the raga . The variations of pitch about a note are allowed in each raga so by studying variations of pitch we can identify the raga . Thirdly, in Hindustani music, the repeated distinctive phrases used in a raga are called characteristic-motifs or Pakads which provides meaningful data which is helpful in identifying ragas. The peculiar phrasing varies from one raga to another.

1.1 Objective of the book

The aim of the research work presented in this book, is to find important features of the music signal so that we can classify the raga into different category. It will encourage the scientific research in Indian Classical music, specifically Hindustani music.

The main objectives of the study include:

- Extraction of features of a music signal which are relevant for classification of the music signal using different techniques.
- To determine whether the artists singing the raga during a concert belongs to same gharana or different gharanas by finding the MFCC (Mel frequency cepstral co-efficients ) features of a music signal. Andrew plot is used to study the results.
- Comparison between two types of ragas, one being aesthetically known to be restful raga and the other restless in nature is done by finding statistical features. Distinction between the two types of raga is done by finding the mean, standard deviation and Inter onset interval. The Transitory and non-transitory frequency movements between the notes of both ragas is determined.
- Statistical Modeling of ragas is done to distinguish between Restful ragas and Restless Ragas. Simple Exponential smoothing techniques is used for Modeling the Restless Ragas Pilu and Bhairavi and Double exponential Smoothing techniques is used for Modeling the Restful Raga Todi .
- The work is focused on music emotion representation. The characteristics features of music signal such as rhythm, melody, pitch and timbre are studied. Among these which parameter(s) play a major role in creating happy or sad emotion in the song or music samples are studied.

1.2 Outline of the book

Following the research objectives, the rest of the book is organized as follows:

Chapter 1 presents a brief introduction of the work done in the book.

Chapter 2 presents a brief introduction for the classification of music signals, different techniques used for features extraction, important characteristic of ragas and statistical modeling of raga.

Chapter 3 presents different audio features and its extraction techniques, study the artist behaviour of different Gharanas from Raga performance. Todi Raga and Bihag Raga are used for investigation through their corresponding music signals. MFCC features are extracted for the two raga and Andrew plot is created to find the similarity if same raga is rendered by two artists of same gharanas and the difference if same raga is rendered by two artists of different gharanas.

Chapter 4 deals with Comparison between Restful and Restless Ragas. In this basic Statistical Features such as mean and standard deviation are used. Comparison is done between Todi and Bhairavi Ragas. Analysis of transitory and non-transitory frequency movements between Notes of Todi and Pilu Raga is also carried out.

Chapter 5 discuss the Statistical Modeling of Restful Ragas and Restless Ragas. In addition to statistical modeling, other features such as Rate of Change of Pitch and Inter-Onset Interval are also used to distinguish between Restful and Restless Ragas. Simple Exponential smoothing techniques is used for Modeling the Pilu and Bhairavi Ragas. The performance of both ragas is analysed.

Chapter 6 Double exponential smoothing techniques is used for Statistical Modeling of Todi Raga . The performance of Todi raga is analysed in detail for several recordings.

Chapter 7 discusses the parameters which are responsible for different emotion (sad or Happy) in the music sample. Statistical parameters representing a musical phrase can be divided into two groups: statistical parameters describing melodic quantities of musical phrase (P1, P2, P3) and the parameters describing rhythmical quantities of musical phrase, ( P4, P5). Their formulae are detailed in the thesis. .In every song samples melodic quantities and rhythmical quantities of musical phrase are evaluated through these five statistical parameters. It indicates why a particular song evokes a certain emotion. It turns out that the melodic parameters have high values in sad songs and rhythmical quantities of musical phrase have high values in fast track happy songs.

Chapter 8 provides the main contributions and findings of the study and concludes the accomplished work.

Poonam Priyadarshini

Soubhik Chakraborty

Chapter1

Introduction

1.1 Background and motivation

With the development of technology in multimedia large amount of digital music is available on the internet and on personal devices. People are listening to the music of their choice for enjoyment. To listen the music of their choice listeners have to search the music from large database available on the internet by song title, composer, performer, mood (happy or sad song) and culture specific tags. In order to make their collections easily accessible to the people, music libraries need to classify music by genre, instrumentation, tempo and mood etc. In order to structure and organize large music files on the internet and make the desired music easily accessible to the consumer, important features of music signal are calculated so that music files can be categorized into different group such as Genre, Artists, style, emotion etc. The acoustic features of music signal are pitch, timbre, rhythm and melody [1-3]. Extraction of relevant information from the sample data in compact form is called features extraction [4-7].

Indian classical music is derives in 12th century. Indian classical music is highly influence by Indian culture. “Vedas” the earliest guidebook in the Hindu culture, shows the origin of the Indian classical music. Indian music is considered as oldest music in the world .The ‘Indian music’ are known in the other nations. Oldest scriptures shows that the Indian music flourished in subcontinent like India, Pakistan, Bangladesh, Nepal, Tibet, Bhutan and Afghanistan. Indian classical music is categorized into two parts as Carnatic music or South Indian and North Indian or Hindustani music [8-11]. Delhi, Lucknow, Benares, Calcutta, Varanasi and Farrukhabad are the main city of India where Hindustani music mostly flourished. Hindustani music is heavily influenced by Aryan peoples from the middle east .The Carnatic music is also known as South Indian and is mainly located in Chennai and can be found in the southern part of the country. The other categories of music are folk, tribal, kirtan, bhangra, Indi-pop, film songs and sonnet. The Dhrupad, Khayal, Thumri, Dadra, and Tarana are the different musical forms Indian classical music. Dhrupad, Khayal and Thumri are the essential musical forms Indian classical music . Alap and Bandish or Gat a typical interpretation of a Hindustani raga.

It is a challenging issue to determine the ragas in Indian music[12-15]. The reasons for recognition of raga has problem as follows. (i) For composition of a music piece many instruments may be used during a concert. (ii) The notes used in the music piece are on a relative range rather than on a absolute range (iii) In Indian music first note of a raga are not having any particular pitch[16]. (iv) Indian music do not have a firm periodicity around a note, rather chain of repetition exists about a note. (v) The notes arrangement order in the ragas is not firm and distinct spontaneity is granted by the performer while singing a raga so that a specific emotion is created in listeners mind[17].

The challenges can be minimized by finding the structure in a raga which can be easily captured.(1) The most prominent swara used in a raga can be determine by measuring number of existence or the extent of each swara in a raga sung by the artist [12]. This may give intuition into the set of notes and their repetition in a raga, thereby benefitting in recognition. (2) By finding Gamakas and Pakads used in the raga[18] . The variations of pitch about a note are allowed in each raga so by studying variations of pitch we can identify the raga[19] . (3) In Hindustani music, the repeated distinctive phrases used in a raga are called Characteristic-motifs or Pakads which provides meaningful data which is helpful in identifying ragas. The peculiar phrasing vary from one raga to another.

Music can also be considered as a sound, through which different meanings can be expressed which creates different feelings in the audience mind. Raga helps to cure mental disorder and other diseases. Music has influence on the body and mind of the performer and listener. The disease or disorder is cured from the root or permanently. When this music is played in chorus and consistency in different forms is called as Tala and Raga, it is feasible to change the mental impression as well as get rid of the physical illness. Music Therapy is used for curing patient suffering from brain injury[20]. In Nature Cure, a disease is due to inequality of the Pancha Mahabhutas in the body. When the body and mind are compatible and not in stress then body is in healthy condition. The conventional Classical and Hindustani music acts on the body, mind and soul of the artist and also on the listener.

Music play a important role in human being life. Learning music has a soothing effect in the mind of performer but when people listen to good music then there is increase energy, spontaneity, pleasure, alertness of the people. Every cell in the body is empowered there is gain in strength with peace of mind. Music can play an efficient role to benefit us and lead better and rewarding lives. Listening to distinct kinds of music at exact times of the day has shown to be helpful in supporting good health.

In the twentieth century Vishnu Narayan Bhatkhande (1860-1936), is one of the most prominent scholarly people in the area of North Indian classical music. He explains that each one of the raga is based on ten basic thaats. Each one of the raga is originated from these ten thaats only. Bilawal, Kalyan, Khamaj, Bhairav, Poorvi, Marwa, Kafi, Asavari, Bhairavi and Todi are ten thaats of Indian classical music. Whenever a raga is picked at random, it is build from on anyone of these Thaats. All thaats are ragas also but a thaat is an entirely distinct musical element from a raga.

While raga is an arrangement of notes in a specific pattern and raga can’t be realised upon the printed page. Each raga has a phrase called pakad which is sung by the singer at the starting of the raga in the concert so that raga rendered by the artist can be easily identified by the audience. Identical notes can be used in two different raga but two raga sounds different as the arrangement of notes is not the same in both of the raga. There is variation in pitch on the notes.

Thaat contains all the seven notes where as a Raga may contain only five, six, or seven notes or the combination of anyone of these notes. Raga have the capability of creating emotion in listener mind where as that don’t have such features.

A thaat is a musical range, realize of as a Western musical range might be, with the seven notes given in their order of ascent (arohan).

1.2 Unique characteristic of Indian music

Indian Classical Music, and indeed music universally, is built on the foundation of the seven basic swaras named as shadja, rishabh, gandhar, madhyam, pancham, dhaivat and nishad, and represented as Sa, Ri , Ga, Ma, Pa, Dha, and Ni. Sa is the origin note and rest of the notes are arrange accordingly[21-24].

Indian music is monophonic (solo singer) in nature while western music is polyphonic (more singer singing simultaneously), consistent or a combination of both. Indian Classical Music concentrates on melody and rhythm, whereas Western Classical Music has harmony and counterpart features which distinguishes it from Indian Classical Music. In Indian Classical Music (Sa) ,the first note is not correlated with any established values of pitch and other notes are realised accordingly with Sa as reference point whereas in Western Classical Music the tonic note have a fixed value of pitch . In Indian music the notes are not on a complete scale but on a relative scale. Indian music do not have a firm periodicity around a note, rather chain of repetition exists about a note. In Indian music there is no equal interval between the seven notes of the scale. On the musical scale, positions of the first note (Sa) and fifth notes (Pa) are not altered. There is no script to follow which is notable characteristic of Hindustani music. The nucleus of Indian Classical Music is the raga. Raga is an unique arrangement of notes, following a set of rule that is arohana or avarohana pattern of notes sequence in a raga which is specific for each raga and creates an emotion in the listener mind[25-26]. The sequences of swaras played by artists in the ragas are not fixed and various spontaneity are allowed by the performer while citing a raga to create emotion in audience mind.

Indian classical music has Swara and Taal as their basic components. The Indian musical system is modal. In a modal system, similarity among successive notes as well as those within any note and the tonic (first note of a musical scale—Sa) are of paramount importance. It is essentially spontaneous in nature, the performer is the composer. India’s music task is on the basis of melody where as Western music work on harmony. Sequences are of importance, not chords. The trademark of Indian music is the unlimited field and it offers for spontaneity and facility. Indian classical music is not harmonize nor written down as Western music. While the scheme imposes great regulation, within the space the performer can bring his or her intelligence into full play.

1.3 Characteristic of Music

Drone

In music, a drone is a monophonic effect where a note or chord is continuously sounded throughout most of a piece [27]. Monophonic mean the smooth musical pattern, expressed by melody generally sung by a solo singer or only one instrument is played .There is no harmony or chords in the music piece. A drone effect can be achieved through a continue sound or through repetition of a note. A drone can be instrumental, vocal or both.

Raga

Raga is word "which glow the mind". The nucleus of Indian classical music is Raga. Indian music has seven basic swaras named as shadja, rishabh, gandhar, madhyam, pancham, dhaivat and nishad, usually written in short form as ( Sa, Re, Ga, Ma, Pa, Dha, and Ni) also called “Saptak”[30-32]. Mandra, Madhya and Tara are the pitch ranges for saptak in Indian classical music.

Madhya Saptak: The pitch obtained from tonic Sa to Ni.

Mandra Saptak: The seven swaras whose frequency is exactly half the frequency of Madhya saptak is called Mandra saptak.

Tār Saptak: The seven swaras whose frequency is double the frequency of the Madhya saptak is called Tār saptak.

Ati Mandra Saptak is those saptak whose pitch values are lesser than the Mandra Saptak. Ati Tar Saptak is those saptak whose pitch values are more than the Tar Saptak (which is twice the frequency of Tar saptak).

Saptak are the seven swaras from Sa to Ni and Octave means the eight swaras denoted by C to C‘. An octave is the period between one musical pitch and another musical pitch whose frequency is either half or double.

Western counterpart of Indian music is ( Do, Re, Mi, Fa, Sol, La, and Si). Raga is an arrangement of notes that have specific properties such as aroha (ascending), avaroha(descending) ,Tala and Pakad [28-29]. Other characteristics include Vadi note and Samavadi notes. To classify the melodic line in a raga minimum five notes or more are used. A set of order is maintained in placing the notes when raga is sung by artists so that no two ragas will have the same melody framework. Notes are arranged in ascending order or in a descending order. Each note have a specific fundamental frequency which may be higher or lower than other note frequency , An ascending or descending pattern is formed when there is transition from one note to another note in any melody. Aroha means the ascending transition from one note to another note while a descending transition from one note to another note is term as Avaroha. A roha and Avaroha arrangement of notes leads to the formation of a distinct raga. Raga is specific arrangement of notes which when sung by singer creates different emotion in listener mind. The oscillatory movement around the note is called as gamaka. The raga are highly ornamented by slides called Gamaka. Gamaka are also created by making a sliding movement from one note to another. The unique property of Indian music is that singers are allowed to slide between the notes in a raga. In Indian classical music ragas are performed at specific time in a day known as morning raga, evening raga and night raga .Some ragas are performed at particular season of a year so that emotion related to that season evokes within the listener and artists mind. The Raga gives an artist the element range to build the melody from sounds, while the Tala provides her with a creative structure for rhythmic spontaneity using time. The literal explanation of the raga is much extended than a scale. Raga is a technical selection of notes which depicts aesthetic qualities such as sentiment, colors, creator, seasons such as winter, summer, spring and autumn, periods of day, carnival events, and can also convey fascinating effects.

Tala

Tala interprets a time cycle in a composition which is used to compose the musical piece. In Indian music Tala is used in all form of music like vocal, instrumental and dance. Tala is rhythmic beat which is performed by body language such as clapping of hands, fingers to indicate number and waves. Adi tala is being counted with these hand gestures. Every tala has its own peculiar arrangement or distribution. The distinct arrangement of talas gives rise not only to a diversity of cycles but also affect the motive in singing and drumming to a great extent. Solakattu is an essential device of the tala system. Solakattu is the tradition of reciting syllables called “jati” which harmonize with various drum strokes and are used as both a work practice and a mnemonic device for training rhythmic composition. During a conduct these jatis may be recited to follow dance movements or solo instrumentalist (without using musical instruments). Spontaneity in raga is done by simple rhythmic patterns associated with each tala.

Melody

A timely arranged linear sequence of pitched sounds that listeners perceive as a single entity is called melody. Melody is a line of single tones that move upward, downward, or repeat. Melody stays at the same level. Range of the melody is the distance from highest to lowest pitch.Melody is a combination of short and long notes combined with moments of silence. Melody moves by large leaps. A melody that uses mostly small scale steps, rises and falls slowly, with only small changes between one note to the next note and is smooth is said to be a conjunct melody. A melody that uses large intervals is called a disjunct melody. Melodic Contour or Shape is ascending or descending.Melody is created using different patterns of Notes in a Musical Scale. Melodies can be derived from various scales (families of pitches) such as the traditional major and minor scales of tonal music. Melody typically consists of several consecutive musical phrases.. Melody may be considered as most prominent lines in a piece of music, the line that the listener follows most closely. Melody has a number of different characteristics such as phrase, contour and interval. Melody is the main theme of a piece of music.Sometime melody is considered as a theme for composition of songs. A balance between similar and contrasting rhythms makes a melody interesting.

Harmony

Two or more notes played together at the same time. More than two notes played at the same time of different pitches produce Chords. Chords provide fundamental building block for Harmony in Western Music. Combinations of certain notes sound pleasant and certain others sound annoying (dissonant) based on harmonic interaction between different frequencies. The study of Harmony connects chords and their construction and chord advancement. In Harmony each notes have different pleasing effect during singing the raga or song. The sound is having pleasant effect when notes are combining in the following sequences.

1. Shadja and Madhyama (Sa-Ma Combination of 1st and 4th Notes )
2. Shadja and Pancham (Sa-Pa Combination of 1st and 5th Notes)
3. Shadja –Gandhār (Sa-Ga Combination of 1st and 3rd Notes)

Harmony is creative, while melody is purely emotional.

Rhythm

The word rhythm comes from the Greek, meaning measured motion.A response to music of sound sequences of certain characteristics, comprising experiential as well as behavioural aspects is term as Rhythm. Rhythm is a pattern that repeats. Rhythm specifies starting times and durations for individual notes. Notes of different durations are organised into patterns. The pattern or musical quality produced by the repetition of stressed and unstressed syllables is also term Rhythm. Rhythm classify succession of strong and weak ingredient and made up of sounds and silences which get repeated. A rhythm has a steady beat, but it may also have different kinds of beats. Rhythm as a design principle is based on repetition of colors, shapes, forms, lines or value contrasts. Rhythm in art, as in music, may change from one work to another.

Timbre

Timbre is the quality of sound, sound of different instruments. All the different sounds an instrument can create .The capabilities of an instrument, what parameter makes it different from other instruments. Timbre can also refer to the variations in tone color of a specific instrument (a bright guitar or dark voice).

Dynamics

Volume changes from soft to loud in music. Dynamics can change suddenly or gradually. Crescendo is known as continuous increase in volume and Decrescendo is known as progressive decrease in volume where as sudden change in volume is known as Subito.

Texture

Texture is the relationships between the different instruments within a piece of music.

It can be Monophonic (one voice or an instrument), Polyphonic (music with independent voices singing simultaneously) and Homophonic (Melody with accompanying chords). In music, texture is how the tempo, melodic, and harmonic materials are combined in a composition.

Key

When pitches are grouped together in a music pieces then it is term as key. All the notes within a certain key have some essential characteristic which is common to the notes. Tonic notes and chord are identified by key. A scale is an ordered set of notes normally used in a key, while the key is the "center of gravity" build by distinct chord progressions. A scale is a series of notes in which the first and last are usually the same, organised to a particular pattern. Keys are created when the first degree (tonic) and fifth degree (dominant) are used in ways that give framework and to some amount ‘meaning’ to the pitch ingredient of the music.

Metre

Meter means how the beats are organize. Beats are grouped in one of this form such as 2, 3 or 4. Mostly first beat is significance. Organization of music into regularly recurring measures of stressed and unstressed "beats“. In Western music notation it is indicated by a time signature and bar-lines. Simple Meters divide the beat into two equal part and Compound meters divides the beat into three equal part.

Different values of melody, duration and rhythm exist in various forms of music of Hindustani music. North Indian music is further divided in three parts named as classical, semi-classical and light music.

The various forms of Classical music are Dhrupad, Dhamar, Khayal, Taranā and Tappā. The duration of the performance of these forms can lie between 3 -60 minutes, which spare only 5–10 percent of the total performance timing to the main composition. Rest of the performance consists of improving melody and variation in rhythm pattern with variation in speed and laya.

Semi-classical music comprises of the forms: Thumri, Dādra, Kajri, Chaiti, Sawan, Jhula. The duration of the performance of these forms lasts for about 10 –20 minutes, 30 percent of which is given to the composition and the rest includes improvisation.

In light music, there are various compositions such as songs geet, bhajan, ghazal, etc. They have been named as per their theme of lyrics and style of composition. In such proceedings, normally one composition takes upto 5 to 10 minutes. Each line of the song is taken to be equally important in the performance.

Indian music has melody and Rhythm as necessary parameter. The music is based around a melodic mode sung to a rhythmic cycle. Both the Hindustani and Carnatic music is based on the same principle to make use of Raga and Tala in the music piece. The actual pitch content of the raga and the measure of the tala are usually different. There is a difference in expository techniques, ornamental style and use of tempo. Indian classical music puts great emphasis on improvisation. The Indian classical music is monophonic in nature and based around a single melody line. Instruments found in Hindustani classical music include the sitr, sarod, surbahar, rudra veena, violin, sarangi, bansuri, shenai, santoor, harmonium, jaltarang, tabla, pakhawaj, and tanpura. Though a given raga has peculiar melodic phrases, they are not limited .Raga is neither just a set of notes, because different ragas have same set of notes yet sound very different because of the various properties of raga. The arrangement of the notes(called arohana/avarohana which mean ascending/descending patterns respectively), the way they are emphasis using various movements (called Gamakas ), their relative position, strength and duration of notes (i.e., various functions of swaras). Even a given raga is used to tune numerous compositions by various people, it is always possible that a new tune can be composed using that raga.

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