25-08-2017, 09:32 PM
AN ANALOG INTEGRATED-CIRCUIT VOCAL TRACT
PRESENTED BY:
NIEL V JOSEPH
S7 AEI
College Of Engineering, Trivandrum
PRESENTED BY:
NIEL V JOSEPH
S7 AEI
College Of Engineering, Trivandrum
An analog integrated circuit vocal tract.ppt (Size: 1.33 MB / Downloads: 80)
Introduction
Human vocal tract
Concept of speech locked loop
Circuit model of vocal tract
Two -port ∏ -section
Linear and non linear resistor modeling
Driving the vocal tract
conclusion
INTRODUCTION
First experimental integrated circuit vocal tract
16 stage cascade of two port ∏-elements
Analysis by synthesis
Speech locked loop
Human vocal tract
Function is filtering of sound
Consist of laryngeal cavity, pharynx, nasal cavity and oral cavity
Length in adult males is 16.9 cm and in females 14.1cm
Larynx produces sound in mammals
Lungs act as power supply
controlled variations in the area of vocal tract produces speech
Two sources of excitation are
Periodic source at the glottis
Turbulent noise source at some point along the tube
Vocal fold vibrations produces interruption of airflow
CONCEPT OF SPEECH LOCKED LOOP
Analysis- by -synthesis
Analogy with phase locked loop
Measure of error is computed by comparing to the input
SLL locks to the input sound with optimal vocal tract profile
Vocal tract is analogous to VCO in PLL
CIRCUIT MODEL OF VOCAL TRACT
The wave equation for one dimensional sound propagation in a uniform tube of circular cross section is
P-sound pressure
U-volume velocity
A-area of cross section
C-velocity of sound
Acoustic wave propagation in a tube is analogous to plane wave propagation along an electrical transmission line
Equation can be modified as
Transmission Line (TL) model
TL comprises of cascade of two-port elements
Current source model
Variable impedance model
Fluid volume velocity is mapped to current
Fluid pressure is mapped to voltage
TWO-PORT ∏-SECTION
LINEAR AND NON LINEAR RESISTOR MODELING
Implemented with MOS transistor
Glottal constriction resistance is a series combination of linear and non linear resistors
For linear characteristics I ∞V
For non linear characteristics I ∞√V
DRIVING THE VOCAL TRACT
It can produce all speech sounds
We should be given area function, the glottal excitation source, the turbulent noise source
Area function has large number of degrees of freedom
To reduce the dimensionality we use Maeda articulatory model
The Maeda articulatory model describes the vocal tract profile using seven components
Jaw height
Tongue body position
Tongue body shape
Tongue tip
Lip height
Lip protrusion
Larynx height
Articulatory code book contain mappings from the articulatory to acoustic domain
Set of vocal tract profiles are generated
‘babble’ is synthesized using each vocal tract profile
DCT is applied to generate a set of 12 cepstral coefficient
Compared against the codebook
Best match is found and corresponding articulatory parameters are used to produce vocal tract area profile
CONCLUSION
Consumes less than 275 micro watt power
Used in speech locked loop to generate speech
Cross sectional area of tube can be varied by varying L/C
Also used in speech compression an speech recognition
REFERENCES
B. Raj, L. Turicchia, B. Schmidt-Nielsen, and R. Sarpeshkar, “An FFTbased
companding front end for noise-robust automatic speech recognition,”
EURASIP J. Audio, Speech, Music Process., vol. 2007, 2007,
10.1155/2007/65420, Article ID 65420.
R. Sarpeshkar, M. W. Baker, C. D. Salthouse, J. Sit, L. Turicchia, and
S. M. Zhak, “An ultra-low-power programmable analog bionic ear processor,”
IEEE Trans. Biomed. Eng., vol. 52, no. 4, pp. 711–727, Apr.
2005.
L. Turicchia and R. Sarpeshkar, “A bio-inspired companding strategy
for spectral enhancement,” IEEE Trans. Speech Audio Process., vol.
13, no. 2, pp. 243–253, Mar. 2005.