<< Chapter < Page Chapter >> Page >

Figures 2 and 3 show a couple of examples of the data for each speech frame for two spoken words. The word in Figure 2 is “help” and the word in Figure 3 is “free”.

If you look closely at the speech data for the word “help” you will notice that, for a particular voiced sound, the value for each reflection coefficient (K’s) of each frame varies somewhat from those of the neighboring frames. With hand editing by an expert ear, many of these frames could be replaced by one of its neighboring frame’s data (see frames 8, 9 and 10 in Figure 2). If frames could have their K values replaced with those of an appropriately chosen frame, a repeat frame could be used – therefore, 10 bits could represent the frame rather than 48 bits for a voiced frame or 28 bits for an unvoiced frame. Figure 3b shows repeat frames for the synthesized word “free”.

The idea of repeat frames giving better quality became obvious to me as I was editing the spoken phrase “Texas Instruments”. I had trouble making the word “Texas” sound correct. I finally slowed the word down and realized that the “eh” vowel sound (in the word Texas) had been turned into a diphthong (two different sounds) giving a vowel sound of “aa – eh”. This should have been expected as the professional speaker was a Texan with a good Texas accent (I’ll tell other stories about the issues we had with a Texas accent later). What was amazing was that I could take any one of the 8 or so frames and repeat it through and make the sound of the word “Texas” better. What I was doing was reducing the string of vowel sounds to just one. This edit gave a better quality at a lower bit rate.

Coefficients for the word "help" before compression.

The spectral graph of the word Free before and after data compression.
The speech data for the word “Free” after compression. Note that the data rate after compression is 775b/s.

I've attached an appendix (Appendix 3) for those who would like to know how the speech data was formatted in the ROM. It is not a topic I thought would fit well into this chapter, but one which would be interesting to some readers. With all of this as background, let’s now discuss some of the compromises we made in a bit more detail.

Sample rate

The sample rate determined the frequency response of the sound output. The higher the sample rate the better the sound would be, particularly for the unvoiced sounds. But the higher the sample rate, the higher the data rate. Although it can be argued that this is not necessarily the case, we understood that there needed to be more reflection coefficients to capture the data properly at a higher sample rate. It seemed to follow a rule of sample rate plus two to determine the number of reflection coefficients. We didn’t have time to evaluate this rule so we chose to use the simpler solution of ten coefficients, sampling at 8kHz.

At the time we began to find the professional speaker for the product, we noticed that not everyone had an “LPC friendly” voice. One of the early speakers we looked at was marvelous at doing character voices. We used him to give a voice to several of the options we had for the final name of the product. Here are a few of those choices:

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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Berger describes sociologists as concerned with
Mueller 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, The speak n spell. OpenStax CNX. Jan 31, 2014 Download for free at http://cnx.org/content/col11501/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'The speak n spell' conversation and receive update notifications?

Ask