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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

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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.
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
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
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
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
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
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Source:  OpenStax, The speak n spell. OpenStax CNX. Jan 31, 2014 Download for free at http://cnx.org/content/col11501/1.5
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