Full formant analysis with Akustyk

Quick LPC

Before you run the full formant analysis, it is recommended to run Quick LPC first. Quick LPC will give you a preview of LPC analysis results.

1. Open an audio file
2. Click Edit
3. In the Editor window, select the vowel you want to analyze
4. You can zoom in on the vowel for more accuracy. Place the cursor where you want to take your measurements
5. Go to File, Quick LPC.

If you are happy with the results, you can now go onto the full formant analysis.

Where to measure?

One of the most common questions about formant analysis is where to take LPC measurements. The answer is not a simple one. The general rule of thumb is that in monophthongal vowels, you need to find the so-called "steady state" - a portion of the vowel nucleus whose formants remain unchanged for a sustained period.

Let's now look at the spectrogram of the word "test." You will notice that the dark, thick bands of energy - the formants - are more or less parallel to one another.

Diphthongal vowels, on the other hand, rarely have a steady state, as the formants change throughout the entire duration of the nucleus. Let's look at the word "coat" to illustrate the point.:

In any event, Akustyk will give you the tools to perform accurate analysis of both monophthongal and diphthongal vowels.

Performing full vowel analysis

To perform full vowel analysis:

1. Open audio file
2. Select it and click Edit
3. In Praat Editor, put the cursor where you want to perform the analysis. For more accuracy, you may want to zoom in on the vowel by pressing Ctrl+ n (Cmd+n on the Mac).
4. Go to File
5. select Formants

Note : If Akustyk is installed properly, you should be able to use the CTRL+F12 keyboard shortcut (from within the Editor) to perform full formant analysis.

1. Fill in the form (it is best to fill in all fields to avoid missing information)
2. Select vowel label (see the appendix of the manual for explanation of the vowel symbols). There is a separate form for each language that Akustyk currently supports. So if you've set German as your default language, ONLY GERMAN vowel symbols will appear in the form.
3. Type in the word
4. Type in Subject code (use ordered integers only. Start with 1, e.g., 007)
5. Choose Subject sex
6. Enter the preceding environment (type "none" if word-initial)
7. Choose the preceding feature
8. Enter the following environment (type "none" in word-final)
9. Choose the following feature
10. Choose syllable stress (1 = primary, 2 = secondary, 3 = tertiary)
11. Check "LPC graph" to draw an LPC graph
12. Check "FFT graph" to draw FFT graph
13. Check "No file" if you DO NOT want to add this analysis to the spreadsheet.

Reading the analysis summary window

Let us now look at the analysis summary window. This is a summary of the full spectral information that is written to the spreadsheet.

1. formant values in Hz
2. formant amplitudes in dB
3. bandwidths in Hz
4. formants and bandwidths in Bark
5. F0 and intensity at cursor - you will see that a more accurate measurement of F0 is done during interval analysis.
6. file information - the sample rate, the LPC order used, and the number of expected formants.

Interval analysis

Let's now look at interval analysis. Interval analysis takes LPC and F0 readings in brief intervals (about 10 ms long) and performs a series of analyses at each interval. This is particularly useful for analyzing diphthongal vowels. As in this example of the word "coat"

To perform interval analysis, we follow the same steps as in the case of simple analysis, but we check the "interval analysis box"

1. Make sure you check "Interval analysis" at the bottom of vowel analysis form
2. Program will pause and you will see a pop-up message saying "select the area for interval analysis in Editor"
3. Before clicking "continue" return to Praat Editor window and select the entire duration of the vowel you want to analyze
4. Return to the form and click "Continue"
5. Akustyk will finish the analysis and display results in the INFO window

As you can see, we now have separate LPC measurements along the entire vowel. In addition we have the following parameters:

• vowel duration
• detailed pitch analysis