Asoke Kumar Datta

Objective Research Done so Far on Tanpura

This chapter describes a brief review on the study done so far of string plucking for the Indian tanpura. Its goal is to characterize the objective studies done so far on Indian tanpura. The chapter covers a description of ‘jawari’ (enhancing the overtones with varying amplitudes), which is very important in the instrument. Historical background of jawari and its scientific explanation is given in the chapter. Studies on the acoustics of the instrument, done so far, by various authors are mentioned in the chapter. The chapter also contains the numerical and acoustical modeling done so far on the string-bridge vibration forcing on the enclosed stem shell system. It also covers the studies on the effect of tanpura sound on human brain.

Perceptual and Quantitative Evaluation of Tanpura from Its Sound

The chapter presents a study on objective evaluation of a tanpura from the acoustic signals produced from it for the purpose of grading. The first part consists of perceptual grading of 23 tanpuras from signals produced through actual playing of tanpuras by expert tanpura players. These signals are perceptually evaluated by four different groups consisting of expert musicians, tanpura players, senior and junior scholars of music. The perception study consists of grading each tanpura into a four-point scale by individuals in each group. In the second part of the experiment spectral structure of each tanpura signal is studied and some parameters are selected for evaluating the musical quality. An objective evaluation is made using multiple regressions with these features and the subjective evaluation. The results show that an objective evaluation of tanpura from recorded signals conforming to the subjective evaluation is possible with 95% level of confidence. This chapter also intends to present an analysis of some selected spectral parameters for evaluating musical quality. The amount of energy present in the frequency band of 60 Hz–1 kHz and in the band 1–3 kHz are two features in the long-term average spectra over the whole cycle. To capture the gross time variance of spectral quality the whole length of the signal for one cycle is divided into 5 equal segments. The difference in amplitude (expressed in dB) between two largest peaks in the average power spectra for all these segments is also examined. For this purpose 4 tanpuras, 2 good and 2 bad selected through an elaborate perception experiment, are properly tuned and played by the professionals. The signals are digitized and the spectral analysis is done using standard software packages for spectral analysis. A comparison of the values of spectral parameters of individual string with those corresponding to the combined spectra of actual playing is also presented.

Evaluation of Musical Quality of Tanpura by Non Linear Analysis

Tanpura, multi-stringed instrument used as a drone instrument, is an integral part of Indian classical music. Tanpura signal is considered as repetitive quasi-stable geometric forms. Instability of geometric forms must be related to some sort of non-linearity associated with the strings and their mode of attachment and/or some feed-back mechanism which uses the total acoustic environment. One way to analyse this is to study the fractal and correlation dimensions. In the present study 40 signals from four strings each for ten tanpuras have been used for analysis. Variation of D0, and D2 with pitch for each strings and their interdependence is discussed. The chapter also investigates the grading of the instrument by their musical quality by analyzing the Hurst exponent of each instrument by Detrended Fluctuation Analysis (DFA) and comparing the same with the grading done perceptually by an expert.

Making of Tanpura with All Its Components, Tuning and Playing

Tanpura or Tambura is perhaps, the only musical instrument that creates the ambiance in almost every Indian musical concert. The musical world is amazed by its simplicity and at the same time inquisitive about, how just within a few finger touches on Tanpura generates simple buzzing sound that conveys its Indiananess. From early days to contemporary, there were some modification occurred in the procedure of Tanpura making. Gradually, some centres of Tanpura making became prominent and renowned. In this chapter we have discussed about the rudimental and structural parts of Tanpura. From this chapter one can get a clear and in depth picture of Tanpura with nomenclatures. The chapter contains the detail construction of tanpura with its different parts. It also mentions about their measurements, shape and size. Different steps of tanpura making covers the plantation of gourd and its processing, seasoning of wood and the fitting of different parts including the decoration and polishing. Even the process of preparation of the glue for pasting the different parts of tanpura is discussed. The chapter also covers the process of tuning of the instrument and a brief discussion about the musical instrument industry in India. All these have been discussed with proper illustrations in this chapter.

Jitter, Shimmer and Complexity Perturbation Analysis

Random perturbations are established phenomena in human speech. Of these jitter has been found to be present in violin sound. The present chapter deals with the nature of jitter, shimmer, complexity perturbations (CP) in tanpura sounds. Significant amount of jitter and shimmer is observed in all the fourteen tanpuras. The pair-wise correlation between these parameters and the correlation of these parameters with fundamental frequencies are studied. The absence of correlation, in general, is at variance with the reported findings in case of these perturbations in speech. Each of the three perturbations for all strings in a tanpura are found to be separately coherent while the behaviour between the parameters are not coherent. The nature of the perturbations and their mutual correlation indicate that the source of the perturbations may not lie in the global resonance structure of the tanpura.

Perception of Virtual Notes While Tanpura Playing

One unusual phenomenon observed by many musicians and reported by few researchers is the virtual notes perceived in tanpura drone. Virtual notes are complex tones with missing fundamental. Characteristically one perceives a pitch for such tones which correspond to the missing fundamental. A musical tone can be visualized as a combination of many simple periodic waves or partials, each having its own fundamental frequency of vibration and amplitude. Normally a complex tone has its fundamental and many higher harmonics. For such notes the perceived pitch corresponds to the spectral pitch which is present. Normally a complex tone has its fundamental and many higher harmonics. Musical signals are often found deprived of the fundamental component but not of the perceived pitch. This is the case with tanpura. In tanpura the fundamental is very weak and is often inaudible. Sometime it so happens that the harmonics sends strong signal and the pattern theory of cognition of pitch cognitively dominates and we hear virtual notes. Also often these virtual notes refer to a pitch to which none of the strings are tuned. It then becomes a phenomenon asking for attention. It becomes interesting to investigate these phenomena in some detail to arrive at a good model for relating the virtual note to the harmonic pattern. The present chapter deals with the virtual notes heard by a senior musician in a well tuned tanpura and an attempt to explain those virtual notes objectively.

Physical and Mechanical Properties of Components of Tanpura

In this chapter, we report for the first time the characterization of materials used in the fabrication of an Indian classical instrument, namely the Tanpura. The idea is to study the behavior of different materials from the standpoint of structure-property correlations so that a preliminary understanding can be developed about how the material properties affect musical performance of this Indian classical instrument.

Acoustic Analysis of Tanpura Signals

Four to six stringed plucked accompanying musical instrument, Tanpura, has been investigated in this chapter. The acoustical analysis and the spectral dynamics of the instrument has been studied. Though the strings are tuned to three fundamental frequencies, musicians get a cue of all the notes while performing. The uniqueness of this instrument lies in the periodic fluctuation of the frequency components and the multiple decays in its amplitude. The paper also presents Resonance Balance and the Energy Ratio of all the strings played individually by an expert musician. Four different Tanpuras of scales C, C-Sharp, G and B-Flat were taken for the study. It was shown in the paper that Resonance Balance and the Energy Ratio may be utilized for quality assessment. It also presents a critical analysis of the sound emanated by plucking the thick string (sa) of a male tanpura by an expert musician. Fast Fourier Transform was done in different time segments of the first 2.5 s of the signal. The result shows an abrupt change in the amplitude of the partials, in each time segments between 1000–2800 Hz. The overall amplitude spectrum shows multiple decays. Attempt has been made to explain the nature of vibrations of the string and its correlation with the musical quality. Differences in spectral quality are also investigated between Indian and German strings in Tanpura. The chapter also presents a comparative study on the spectral structures of a composite string sound prepared in the Laboratory by superimposing the sound after altering the pitch of the initial sound with a delay of 0.01 s., with the natural Tanpura sound (thick string). The result shows some similarities between these two sounds which might be helpful to establish a ‘two-string’ model for Tanpura.

Production, Perception and Cognition

This chapter is devoted to muse over the basic principles behind the making of music instead of presenting a synopsis of techniques and technologies used in modern day music production. In the introductory chapter we attempted a comprehensive definition of music. Let us add further that music as an acoustical emotive (except for the emotion of anger, disgust) communication, generally universal in nature. The simultaneity of the three elements acoustics, emotion, and universality (not in the absolute sense) is integral to the definition.

Automatic Musical Instrument Recognition

This chapter deals with analysis of musical instruments especially the Indian musical instruments by analyzing its sound. Sections 9.1, 9.2 and 9.3 concerns the automatic recognition of musical instruments with the idea that extract the perceptually relevant features from acoustic musical signals that a computer system “listen” to musical sounds and recognize which instrument is playing. For this, timbre of the sound of those musical instruments needs to be studied extensively. Only five musical instruments which are popularly adopted in Hindustani music were chosen for study.