# 13.2 Methodology

 Page 1 / 1
Describes the methods we used to detect, identify, and compare formants of a voice sample to the template speaker.

## Purpose

To uniquely identify a speaker based on their vowel formants using frequency domain analysis of a speaker’s voice.

## Overview

The first step in doing Fourier analysis on the speaker’s voice is to first split the signal into windows(see background for more info) such that the FFT(Fast Fourier Transform) algorithm can be used to find the Fourier transform of the signal. This usually just requires that the number of windows is a power of 2, so we chose a window size of 1024 which translates to about .025 seconds in the time domain. This choice allowed us to capture substantial but not excessive information in the time domain. Moreover, we chose to use the hamming window, which has a slower cutoff, to avoid the various negative effects(see background section) that a window with a sharp cutoff can cause. After this process is done on every window we are essentially left with an Array of Fourier transforms, with each transform representing the speaker voicing at different moments in time.

To filter out any excessive noise in frequency ranges where we know vowel information cannot exist (as no human could have a vocal tract that produces vowels with formants in these ranges), we next apply a bandpass filter to our signal in the ranges of 0-100Hz and frequencies above 3500Hz.

Once this is done, the formants and their magnitudes are found in each window by finding the peaks (see Finding Peaks ) within two frequency ranges i.e. where the two formants are known to lie from Tuning. Then a Decision Rule (explained below in more detail) is used to remove all the windows that are sure not to contain a vowel. Using those windows, we calculate a percent error based on where the speaker’s formants lie with respect to the template speaker’s formants, which the system is tuned to (See Tuning ). This process is repeated for every vowel in the English language (each subject wishing to access the system must input in sequence the set of "hVd" words described in the Background section for our trials); once that is complete an average percent error is calculated based on the subject's performance across all vowels and a final decision is made based on this percent error.

## Decision rule

To determine which windows possible contain vowels, the decision rule essentially removes any windows whose formant one or formant two magnitudes differ by more than 2 standard deviations away from the formant one and formant two maximum magnitudes (across windows). It also removes any false positives i.e formants that were detected outside of the possible formant range(above 100Hz and below 3500Hz). What is left are all the windows in which the vowel is being voiced. This essentially filters out all non-vowel windows and to remove any additional noise that wasn’t removed from the band pass filter.

## Tuning

To ‘tune’ our system to the template speaker, we first had to find where the speaker’s frequencies generally lie. This would form the basis for our percent error calculation when checking against another speaker’s formants. To do this we had the user voice every vowel multiple times in which we recorded where we found the first and second formants. These trials were then used to find the range in which the first and second vowel formants lie and the average first and second formant frequencies for each vowel. These were hardcoded into our code for comparison against the formants of the speaker.

## Finding peaks

Finding peaks involved first finding the maximum magnitude in the window and then checking that it's a peak(increasing on the lefts side and decreasing on the right side of the maximum). This prevented false positives, for example detecting a magnitude that may be the highest in the window but is not a peak. To do this we simply have have a sieve that is centered around the maximum magnitude. We then check that values to the left and the right of the maximum magnitude are lower than the maximum magnitude. If this is not the case the sieve moves to the right and a new maximum is found in the window and repeats the process until a peak is found.

## Code

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Berger describes sociologists as concerned with
Got questions? Join the online conversation and get instant answers!