Beyond this, the ratio signal-noise (PSR) and the energy of glottic noise exist (ERG). The ratio signal-noise (PSR), as Yamasaki and Behlau (2001) is measured in decibel and contrasts the total energy of the signal with the noise, but little it is used in the practical clinic, although that the majority of the programs extracts its value. The energy of glottic noise (ERG), express in decibel also measuring the noise of the sonorous wave to the level of glote through the subtraction of the harmonic component of the total energy of the effected acoustic signal for filters whose values are indicated by negative numbers, being the limit of normality until -10dB. Having such measure as base, one sees that values bigger that -5dB, are indicative of fonatria aperiodicidade. The energy of glottic noise is based on the component noise, therefore this pparently is an index more adjusted the differentiation of normal and disfnicas voices of what the ratio harmonic-noise. , When the component noise is bigger, how much thus lesser they will be the harmonic components of the emission (ZITTA, 2005). To study ratio harmonic-noise is important, because he is something that can be made observing normal voices, therefore such is more useful in this type of voices, whereas another measure of noise as the energy of glottic noise, a variant its, is pointed by Behlau et al (2001) apud Behlau (2001), as more indicated with respect to disfnicas voices.
The defense of the ratio harmonic-noise also is seen in Baken (1996), a time that this it considers as one of the best parameters of clinical application, as for the vocal shunting line quantification. This occurs seen this to contrast the regular signal of the vocal folds with the aperidico signal, not only come of the vibration of the vocal folds, but of all the vocal treatment. The express ratio harmonic-noise in decibel the amplitude of the average wave divided by the amplitude of the component isolated noise for each series of cycles analyzed.