VOIDS AND THEIR IMPORTANCE IN THE SIGNALS OF HINDUSTANI VOCAL MUSIC Shankha Sanyal 1 , Archi Banerjee 1 , Anirban Patranabis 1 , Kaushik Banerjee 1 , Nityananda Dey 2 , Asoke Datta 1 , Ranjan Sengupta 1 and Dipak Ghosh 1 1 Sir C V Raman Centre for Physics and Music, Jadavpur University, Kolkata, 700032 2 ITC Sangeet Research Academy, Kolkata 700040 ABSTRACT This study reports the behaviour of voids present in musical signals. It is a scientific approach to understand and measure a particular artistic phenomenon which is rather not much trivial to the musicians. Void means silence. Here we measured the silence along with the signal part of thirty six musical signals of some eminent Hindustani vocalists and tried to understand their singing style in the light of voids. INTRODUCTION Silence isn't just the canvas upon which music is painted. It's one of the colors on the composer's palette. What sets Hindustani music apart from other music forms is that each musician (through improvisation) is also a composer and needs to know how to use silence effectively. We have often thought that a master class should be taught on the role of silence in music because measures of silence are not waiting periods. These are times of active listening, much like a good conversation. Therefore the length of silence, the distance between periods of silence, and the magnitude of silence all might make an effect on the listener. Otherwise it would be monotonous. On the contrary, stopping (pause) for a moment or taking jiffy rest in between two lines or words or tans (pattern of musical notes) etc. is very noteworthy for vocal, especially classical vocal music. Normally, these jiffy rest or pause occurred either for breath taking or as a surprising element (approach) in melodic or rhythm pattern by the singers. In Hindustani classical vocal music the amount of pauses may be different from one gharana to another; even it might differ (a little bit) from artist to artist as per their breathing power and creative emotional perspective. There are many melodic exercises to increase the power of breathing (Sans Bharna) in all vocal gharanas. Other than common approaches there are some special kinds of exercises which depict the gharana’s perspective towards a particular group of ragas. Here in this study we have selected thirty six vocal musical pieces each of duration two minutes sung by eight eminent Hindustani vocalists. We have taken four ragas, viz. Bhairav, Darbari Kannada, Mian ki Malhar and Todi. Nine eminent vocalists are taken for these studies who have sung the aalaps of the above mentioned ragas. In this study these rests or pauses are defined as ‘void’. Both note and void forms the ultimate musical structure. By analyzing these voids along with the notes in the signal and their duration we can get a picture of a particular artist and his style. EXPERIMENTAL PROCEDURE Two minutes of alap were recorded for each vocalist. These signals were recorded and were digitized at a sampling rate of 44100/sec (16 bits per sample) in mono channel. Each signal space was divided into non- overlapping windows of 1048 sample points. These selected sound files are thus selected for analysis, which constitute the database. Pitch extraction technique is defined in methodology. Softwares used are Wavesurfer of KTH, Stockholm and Cool edit of Syntrellium Corporation. METHODOLOGY Since all the thirty six signals are normalized to 0 db and hence intensity or loudness and attack cue are not being considered. Extraction of notes from the pitch profile needs the knowledge of the tonic used by the player. A skilled musician was requested to listen to the signal files one after another to detect the position of tonic ‘Sa’ in the signal file. Here we are following the methodology of finding notes from signal from the theory in [1]. The finding of the ratio-intervals is done by first dividing the smoothed