<< Chapter < Page Chapter >> Page >
Linear prediction is a method used to estimate a time-varying filter, often as a model of a vocal tract. Musical applications of linear prediction substitute various signals as excitation sources for the time-varying filter. This mini-project guides you to develop the basic technique for computing and applying a time-varying filter in LabVIEW. After experimenting with different excitation sources and linear prediction model parameters, you will develop a VI to cross-synthesize a speech signal and a musical signal.
This module refers to LabVIEW, a software development environment that features a graphical programming language. Please see the LabVIEW QuickStart Guide module for tutorials and documentation that will help you:
•Apply LabVIEW to Audio Signal Processing
•Get started with LabVIEW
•Obtain a fully-functional evaluation edition of LabVIEW


Linear prediction is a method used to estimate a time-varying filter, often as a model of a vocal tract. Musical applications of linear prediction substitute various signals as excitation sources for the time-varying filter.

This mini-project will give you chance to develop the basic technique for computing and applying a time-varying filter. Next, you will experiment with different excitation sources and linear prediction model parameters.Finally, you will learn about cross-synthesis.

Prerequisite modules

If you have not done so already, please study the prerequisite modules Linear Prediction and Cross Synthesis . If you are relatively new to LabVIEW, consider taking the course LabVIEW Techniques for Audio Signal Processing which provides the foundation you need to complete this mini-project activity, including working with arrays, creating subVIs, playing an array to the soundcard, and saving an array as a .wav sound file.


  • All LabVIEW code that you develop (block diagrams and front panels)
  • All generated sounds in .wav format
  • Any plots or diagrams requested
  • Summary write-up of your results

Part 1: framing and de-framing

Time-varying filters operate by applying a fixed set of coefficients on short blocks (or "frames") of the signal; the coefficients are varied from one frame to the next. In this part you will develop the basic technique used to"frame" and "de-frame" a signal so that a filter can be applied individually to each frame.

Download and open framing.vi .

The "Reshape Array" node forms the heart of framing and de-framing, since you can reshape the incoming 1-D signal vector into a 2-D array of frames.The auto-indexing feature of the "for loop" structure automatically loops over all of the frames, so it is not necessary to wire a value to the loop termination terminal. You can access the individual frame as a 1-D vector inside the loop structure.Auto-indexing is also used on the loop output to create a new 2-D array, so "Reshape Array" is again used to convert the signal back to a 1-D vector.

Study the entire VI, including the unconnected blocks which you will find useful. Complete the VI so that you can select frame sizes of between 1 and 9. Enable the "Highlight Execution" option, and display your block diagram andfront panel simultaneously (press Ctrl-T). Convince yourself that your technique works properly. For example, when you select a frame size of 2, you should observe that the front-panel indicator "frame" displays "0,1", then "2,3", then "4,5",and so on. You should also observe that the "out" indicator matches the original.

Part 2: time-varying filter using linear prediction

Download the file part2.zip , a .zip archive that contains three VIs: part2.vi, blp.vi (band-limited pulse source), and WavRead.vi (reads a .wav audio file). Complete this VI by creating your own "Framer" and "DeFramer" VIs using the techniques you developed in Part 1.

Create or find a speech-type .wav file to use as a basis for the linear prediction filter. Vary the frame size and filter order parameters as well as the various type of excitation sources. Study the effect of each parameter and discuss your results.Submit one or two representative .wav files.

Part 3: cross synthesis

"Cross synthesis" applies the spectral envelope of one signal (e.g., speech) to another signal (e.g., a musical instrument). Find or create a speech signal and use it to generate a time-varying filter.Find or create a music signal and use it as the excitation. The sound files should have the same sampling frequency.

Repeat for a second set of signals. You might also try cross synthesizing two different speech signals or two different music signals.

Show your results, particularly the spectrograms of the two original signals and the spectrogram of the output signal.

Select your favorite result and submit .wav files of the two source signals and the output signal.

Questions & Answers

how can chip be made from sand
Eke Reply
is this allso about nanoscale material
are nano particles real
Missy Reply
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
where is the latest information on a no technology how can I find it
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
has a lot of application modern world
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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
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
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now

Source:  OpenStax, Musical signal processing with labview -- subtractive synthesis. OpenStax CNX. Nov 07, 2007 Download for free at http://cnx.org/content/col10484/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Musical signal processing with labview -- subtractive synthesis' conversation and receive update notifications?