Skip to content Skip to navigation

OpenStax_CNX

You are here: Home » Content » [ mini-project ] Linear Prediction and Cross Synthesis

Navigation

Lenses

What is a lens?

Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

This content is ...

Endorsed by Endorsed (What does "Endorsed by" mean?)

This content has been endorsed by the organizations listed. Click each link for a list of all content endorsed by the organization.
  • IEEE-SPS display tagshide tags

    This module is included inLens: IEEE Signal Processing Society Lens
    By: IEEE Signal Processing SocietyAs a part of collection: "Musical Signal Processing with LabVIEW (All Modules)"

    Comments:

    "A multimedia educational resource for signal processing students and faculty."

    Click the "IEEE-SPS" link to see all content they endorse.

    Click the tag icon tag icon to display tags associated with this content.

Affiliated with (What does "Affiliated with" mean?)

This content is either by members of the organizations listed or about topics related to the organizations listed. Click each link to see a list of all content affiliated with the organization.
  • NSF Partnership display tagshide tags

    This module is included inLens: NSF Partnership in Signal Processing
    By: Sidney BurrusAs a part of collection: "Musical Signal Processing with LabVIEW (All Modules)"

    Click the "NSF Partnership" link to see all content affiliated with them.

    Click the tag icon tag icon to display tags associated with this content.

  • National Instruments display tagshide tags

    This module is included in aLens by: National InstrumentsAs a part of collection: "Musical Signal Processing with LabVIEW (All Modules)"

    Comments:

    "Developed by Rose Hulman Prof Ed Doering, this collection is a multimedia educational resource for students and faculty that augments traditional DSP courses and courses that cover music […]"

    Click the "National Instruments" link to see all content affiliated with them.

    Click the tag icon tag icon to display tags associated with this content.

Also in these lenses

  • Lens for Engineering

    This module is included inLens: Lens for Engineering
    By: Sidney Burrus

    Click the "Lens for Engineering" link to see all content selected in this lens.

  • NI Signal Processing display tagshide tags

    This module is included inLens: Digital Signal Processing with NI LabVIEW and the National Instruments Platform
    By: Sam ShearmanAs a part of collection: "Musical Signal Processing with LabVIEW (All Modules)"

    Comments:

    "This online course covers signal processing concepts using music and audio to keep the subject relevant and interesting. Written by Prof. Ed Doering from the Rose-Hulman Institute of Technology, […]"

    Click the "NI Signal Processing" link to see all content selected in this lens.

    Click the tag icon tag icon to display tags associated with this content.

Recently Viewed

This feature requires Javascript to be enabled.

Tags

(What is a tag?)

These tags come from the endorsement, affiliation, and other lenses that include this content.
Download
x

Download module as:

  • PDF
  • EPUB (what's this?)

    What is an EPUB file?

    EPUB is an electronic book format that can be read on a variety of mobile devices.

    Downloading to a reading device

    For detailed instructions on how to download this content's EPUB to your specific device, click the "(what's this?)" link.

  • More downloads ...
Reuse / Edit
x

Module:

Add to a lens
x

Add module to:

Add to Favorites
x

Add module to:

 

[ mini-project ] Linear Prediction and Cross Synthesis

Module by: Ed Doering. E-mail the authorEdited By: Erik Luther, Sam Shearman

Summary: 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.

Table 1
LabVIEWq.png 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

Objective

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.

Deliverables

  • 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.

LabVIEW.png 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 and front 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

LabVIEW.png 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.

Content actions

Download module as:

PDF | EPUB (?)

What is an EPUB file?

EPUB is an electronic book format that can be read on a variety of mobile devices.

Downloading to a reading device

For detailed instructions on how to download this content's EPUB to your specific device, click the "(?)" link.

| More downloads ...

Add module to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need an account to use 'My Favorites'.

| A lens I own (?)

Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks

Reuse / Edit:

Reuse or edit module (?)

Check out and edit

If you have permission to edit this content, using the "Reuse / Edit" action will allow you to check the content out into your Personal Workspace or a shared Workgroup and then make your edits.

Derive a copy

If you don't have permission to edit the content, you can still use "Reuse / Edit" to adapt the content by creating a derived copy of it and then editing and publishing the copy.