Skip to content Skip to navigation Skip to collection information

OpenStax-CNX

You are here: Home » Content » Accent Classification using Neural Networks » Extracting Formants from Vowel Samples

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 ...

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.
  • Rice University ELEC 301 Projects

    This module is included inLens: Rice University ELEC 301 Project Lens
    By: Rice University ELEC 301As a part of collection: "ELEC 301 Projects Fall 2005"

    Click the "Rice University ELEC 301 Projects" link to see all content affiliated with them.

  • Rice Digital Scholarship

    This module is included in aLens by: Digital Scholarship at Rice UniversityAs a part of collection: "ELEC 301 Projects Fall 2005"

    Click the "Rice Digital Scholarship" link to see all content affiliated with them.

Also in these lenses

  • Lens for Engineering

    This module is included inLens: Lens for Engineering
    By: Sidney BurrusAs a part of collection: "ELEC 301 Projects Fall 2005"

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

Recently Viewed

This feature requires Javascript to be enabled.
 

Extracting Formants from Vowel Samples

Module by: Phil Repicky. E-mail the author

Summary: A description of how formant frequencies were extracted from vowel samples.

For each vowel sample we needed to extract the first and second formant frequencies. To do this we made a function in MATLAB that we could then apply to each speaker's vowel samples quickly. In an ideal world with clear speech this would be a straightforward process, since there would be two or more peaks on the frequency spectrum with little oscillation. The formants would be simply be the locations of the first two peaks.

Figure 1
Figure 1 (CleanSpectrum.jpg)

However, very few of the samples are this clear. If the formants do not stay constant during the entire clip, then the formant peaks have smaller peaks on them. In order to solve this problem we did three things. First we cut the samples into thirds, found the formants in each division, and then averaged the three values for a final formant value. Second, we ignored frequencies below 300 Hz which correspond to frequencies made when the human vocal tract makes a sound. Finally we filtered our frequency spectrum data to remove noise from the peaks. We also experimented with cubing the spectrum, but the second formant was generally small and cubing the signal made it harder to find. As a guide for the accuracy of our answer we used the open source application Praat. Praat can accurately find the formants using a more advanced techniques.

Figure 2
Figure 2 (NoisySpectrum.jpg)

With the aid of Praat, the first and second formants should be 569.7 Hz and 930.3 Hz. In the unfiltered spectrum there is a strong peak just above 300Hz which does not correspond to a formant, in the filtered spectrum it is removed.

To locate the first formant we started by finding the maximum value in the spectrum. However, sometimes the second formant is stronger than the first, so we looked for another peak before this first guess above a threshold (1.5 on the normalized scale). If a peak could not be found before the maximum to be the first formant, then we had to search for a second formant beyond the first. We did this in the exact same manner as finding the first, but we only looked at the part of the spectrum above the minimum immediately following the first peak. We found this minimum with the aid of the derivative.

This function was used on each vowel sample to generate an accent profile for each speaker. The profile consisted of the first and second formants of the speaker's 14 vowels in a column vector.

Collection Navigation

Content actions

Download:

Collection 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 ...

Module as:

PDF | More downloads ...

Add:

Collection 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

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