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The key to the Speak N Spell actually working the way it had to was the speech synthesis. At the time the program started it was considered an impossible task at any level of technology, not to speak of a "toy". But putting the heads together of two technologists, Richard Wiggins and Larry Brantingham, the appropriate compromises were made to give voice to the product.


The state of the art for implementing real time speech synthesis in a single IC was well defined – it was impossible. These claims were based on the use of the higher performance IC technology known as NMOS. All we had available to us in TI’s Consumer Group was lower performance, much cheaper IC technology, known as PMOS. To no surprise, PMOS was significantly slower than NMOS. But, when all was accomplished, the collaborative effort of Richard and Larry, got the LPC-10 speech synthesis algorithm running using PMOS. What follows in this chapter is a summary of the tradeoffs and compromises made in order to make the Speak N Spell happen.

A quick summary of the compromises:

  • Sample rate
  • Frame rate
  • Multiplier size and data word size
  • Number of coefficients
  • Bits assigned to each coefficients
  • Other tricks

Before discussing the compromises and tradeoffs, it is best to do a quick introduction the concept of LPC here.

Linear predictive coding

After some discussions and analysis (see Richard Wiggins Engineering notebook in Appendix 2) we settled on linear predictive coding.

Appendix 2 is Richard’s complete set of entries into his Engineering Notebook on the Speak N Spell. Here is an excerpt from page 3 of Richard’s Engineering Notebook that does a good job of summarizing his thought process.

“The term linear predictive coding (LPC) refers to the highly successful representation of a human speech waveform as the output of an all-pole filter excited by either periodic pulses (for voiced speech) or by white noise (for unvoiced speech). In these systems, the compressed parameters are the filter coefficients (usually 10 or 12 numbers) and the excitation description (energy level, voiced/unvoiced parameter, and if voiced, a pitch period). This technique has had much recent success in communications systems where good quality speech transmission has been demonstrated at 2400 bits/second. In such systems, the LPC parameters are determined from segments or “frames” of digitized speech, usually about 20 milliseconds in length. Hence a description of the waveform is sent about 50 times a second, with each description being about 48 bits in length.”

The particular solution was called LPC-10 as it had ten coefficients. This was determined to be sufficient for our 8kHz sample rate. As I remember, the reasoning for 10 coefficients was that the number of coefficients for LPC needed to be the sample rate (in kHz) plus two. In this case 8 + 2 = 10. I also seem to remember another reason for 10 coefficients, the idea of needing two coefficients for each formant and two more for the general form of the speech envelope. Figure 1 shows the simplified block diagram for the synthesis algorithm. There were two inputs to the actual filter:

Questions & Answers

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
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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
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
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.
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.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
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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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