process begins at the point of converting an idea developed in the speakers’
mind to a language code. With the aid of articulatory motion and vocal tract
movement, the phonemes which are lined up in a set of sequences propagate
outside as an acoustic waveform.
means protection from all aspects and this protection is to be obtained by
reciting or listening to Pirith suttas.
The practice of reciting and listening to Pirith
suttas began very early in the history of Buddhist culture. As reported by
Jayaratne 2007, an experiment was performed at Kanduboda International
Meditation Centre, Sri Lanka to understand the effect of Pirith on human beings. When a sample of human subjects was allowed
to listen to Pirith chants, it is
observed that within
of the commencement of the chanting, their heart beat reduced, heart pulse amplitude
halved and reached to an alpha state similar to what is obtained under a
Voiced to unvoiced ratio (V/UV ratio) is an
important parameter as it indicates the involvement of speech production system
with vibration of vocal codes. In this work, we combined the results of V/UV
ratio with zero crossing rate (ZCR) and energy of short time segments of the
signal to strengthen the analysis.
In voiced speech, the
vibrating glottis generates periodic pulses which are resonate in the vocal tract.
Therefore, when vowels are pronounced similar frequencies are generated.
However, in the unvoiced speech, vocal chords held open and a continuous air
beam flow through them. The air beam turns into a turbulent flow because of
narrowed vocal tract and it creates, non-periodic, noise-like sounds 8.
The zero crossing rate measures number
of intersections a given signal makes with the time axis per unit time in an
amplitude-time plot. Voiced speech shows a low
zero-crossing rate due to the excitation of vocal tract by the periodic air
flow, whereas the unvoiced speech shows high zero-crossing count as it is
produced by the turbulent airflow flowed through the narrowed vocal tract 1.
Additionally, the voiced part of the speech has high energy content because of
According to the acoustic theory of speech production, vocal
tract is modeled as a non-uniform tube closed at vocal folds and open at the
lip end 9. Cross sectional area of
the vocal tract depends on the position of tongue, lips, jaw and velum. Due to varying
cross section along the vocal tract, different resonance frequencies
(harmonics) are generated in response to varying vocal fold vibrations.
Consequently, the complex output voice signal is composed of several harmonics
called as formants which are clearly visible in spectrographic displays
of voice segments. Normally, they occur on average at intervals of
, where c is the speech of
of the vocal tract 3.
Vowels can be mapped using the
relationship between lip opening width
to the first formant frequency,
and tongue constriction width to second
vowels, which are not of any particular language but a measuring system in
describing sounds of languages are used as a set of reference vowels in this
work. These vowel sounds demonstrate if the tongue is in an extreme position,
either front or back, high or low. The current system was modified by Daniel
Jones * based on the original idea proposed by earlier phoneticians, notably
Ellis** and Bell.**. The standard International Phonetic Alphabet, IPA vowel
trapezium, is shown in figure (*).