<< Chapter < Page Chapter >> Page >
An explanation of the basic problems in analyzing speech patterns.

The questions

The issues with speech recognition in general are complex and wide-ranging. One of the main problems lies in thecomplexity of the actual speech signal itself. In such signals, as in signal 1 below, it is very difficult to interpret the large amounts of information presented to a system.

The word diablo, with DC offset removed.

One of the more evident problems is the jaggedness of the signal. A natural speech signal is not smooth;instead, it fluctuates almost nonstop throughout the signal. Another naturally occurring property of speech patterns is thefluctuation in the volume, or amplitude, of the signal. Different people emphasize different syllables, letters, or words indifferent ways. If two signals have different volume levels, they are very difficult to compare. Speech signals also have a verylarge number of peaks in a short period of time. These peaks correspond to the syllables in the words being spoken. Comparingtwo signals becomes much more difficult as the number of peaks increases, as it is easy for results to be skewed by a higher peak,and, consequently, for those results to be interpreted incorrectly. The speed at which the input single is given is also an importantissue. A user saying their name at a speed different from the speed at which they normally speak can change results, as two versions ofthe same pattern are compared. The problem is, the time over which they are spoken is different, and must be accounted for. Finally,when examining the signal in terms of speech verification, another individual may attempt to mimic the speech of another person. Ifthe speaker has a good imitation, it would be possible for the speaker to be accepted by the system.

The answers

How do you deal with the jaggedness of the signal and the noise introduced to the signal through theenvironment?

  • In order to actually account for this, you have to pass all the signals through a smoothing filter. The filter will accomplishtwo tasks: first, it gets rid of any excess noise. Second, it gets rid of the high frequency jaggedness in the signal and leavesbehind simply the magnitude of the signal. As a result, you get a clean signal that is fairly easy to process.

How do you account for the different volumes of speakers?

  • The signals must all be normalized to the same volume before they are examined. Each signal is normalized about zero such thatall of the signals will have the same relative maximum and minimum values, and so that comparing two signals with different volumes isthe same as comparing the same two signals if they were to have the same volume.

How do you examine each of the individual peaks?

  • Just after the signal is smoothed by the filter, we use an envelope function to detect all of the peaks of the signal. Bydoing this, we can be sure that, if a signal passes a certain threshold amount, it will be examined and compared with thecorresponding signal in the database. The analysis will not be an analysis of the entire signal, but rather a formant analysis. Theindividual formant, or vowel sounds, in the signal will be examined and those will be used to verify the speaker.

How does the system handle varying speeds of inputs?

  • Both the formant analysis and the envelope functions will be used to help with varying input speeds. The envelope of the peakwill determine which vowels are available, and the actual formants themselves will be relatively unchanged. It is difficult to handlevery high speed voices, but most other voices can be handled effectively.

How can you account for imitating speech patterns?

  • Once again, the formants of the individual signals are analyzed to actually determine if a speaker is who he claims to be.In most cases, the imitating formants do not match up closely with those stored in the database, and the imitator will be denied bythe system.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
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
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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 ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
Sanket Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Elec 301 projects fall 2006. OpenStax CNX. Sep 27, 2007 Download for free at http://cnx.org/content/col10462/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Elec 301 projects fall 2006' conversation and receive update notifications?

Ask