©copyright Raimo Olavi Toivonen 1985-2021. All rights reserved. Last updated on Jan 30, 2021.

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Works   Works before ISA

ISA software

LPC spectra in dB/Hz/Bark scale

The calculation uses the PARCOR method. Over the years, I have coded as a DSP man PARCOR-laskennan of the Intelligent Speech Analyser™ (ISA) program
(1) for the Texas 16-bit TMS320 signal processor family in machine language,
(2) for Motorola's 16 and 32-bit M68000 microprocessor families in machine language and C language,
(3) for IBM 600 Series 32-bit PowerPC Microprocessor Family in machine language and C language,
(4) for Intel 32-bit and 64-bit microprocessor families in C++ language.

The windowing of the signal is by a Hamming window, a rectangular window or a Blackman-Harris window of more than 90 dB.

Formants search is performed in a unique way by first filtering the LPC spectral curve by bandpass filtering and then searching the sharpened spectrum for peaks by a unique method.

Analysis pictures I have coded from the very beginning in Neon object-oriented programming language.

Hz is converted to Bark by the formula x/Bark=7ln[f/650+√(1+(f/650)2)] and Barks are converted to Hz by the formula f/Hz=650sinh(x/7).

Hz is converted to ERBs by the formula x/ERB=21,3log10(1+f/228,7) and ERBs are converted to Hz by the formula f/Hz=228,7(10x/21,3-1).

Hz is converted to mel by the formula x/mel=2595log10(1+f/700) and mels are converted to Hz by the formula f/Hz=700(10x/2595-1).

FTT and LPC spectrum of the vowel a:

FTT and LPC spectrum of the vowel e:

FTT and LPC spectrum of the vowel i:

FTT and LPC spectrum of the vowel o:

FTT and LPC spectrum of the vowel u:

FTT and LPC spectrum of the vowel y:

FTT and LPC spectrum of the vowel ä:

FTT and LPC spectrum of the vowel ö: