Ling 600.01 Phonetic Theory
We will do this take-home exercise during the sixth week of the quarter and the final report is due by 1:00 on Monday of week 7 if you want detailed feedback and otherwise by the beginning of class on Tuesday. The final report on in-class lab #4 (on "Measuring formants in English vowels") should be included as an appendix to the report on this take-home lab exercise.
The data for the first part of the exercise are measurements of the first and second formants in the vowels that you and your language consultant produced for the English words that you recorded for in-class lab 4 -- i.e., the measurements that that lab was about. Here are the steps you should take to make those measurements.
Decide where you are going to measure the formants. For example, will you take the measurements at the midpoint of the voiced part of the vowel? Or will you try to identify a "target" or "steady state" point for the measure?
If you decide to measure at each vowel's midpoint, look at a few of the words and make sure that you can identify the beginning and the end of the vowel in a consistent way across all of the words, both for your productions and for the language consultant's productions. Then make a TextGrid object that has an interval tier, in which you place a boundary at the beginning and at the end of each vowel, and a label identifying each relevant interval by a tag for the vowel or the word. If you want, you can download the vowelMidpoints.Praat script from the scripts directory and edit it as necessary for your system, and run it to extract the midpoint formant values.
If you decide to measure at the "target" of "steady state" point for the vowel, look through all of the words, and define some criterion (or set of criteria) for identifying this point in a reasonably consistent way across the different vowels. Then make a TextGrid object that includes a points tier, where you can place a marker for each steady state and a label identifying the vowel or word that each marker points to. If you want, you can download the vowelSteadyState.Praat script from the scripts directory and edit it as necessary for your system, and run it to extract the steady state formant values.
Note that both of these scripts are interactive ones, designed to "pause" at each labeled interval or point so that you can adjust the LPC model as appropriate if the formant values that you see in the red speckles do not match the formant values that you see in the spectrogram on which the red speckles are overlaid. As you extract the formant values -- either by copying and pasting values from the info window or by running the formants extraction script, note the LPC model that you are using. That is, note how many formants you are asking Praat to return and what frequency band you are telling Praat to return that many formants for. Keep track of each word token for which you have to alter the LPC settings to tailor the red speckles specifically for that word.
Whichever method you choose, you should write a short "Methods" section specifying what method you used, what the criteria were for placing the interval boundaries or the steady state points, and what LPC model you used. (By "short" I mean a picture possibly, plus four or five sentences of text at most.) If there were any words for which you had to alter the LPC setting, you might note these in your methods section (and in that case, you can go over the four-sentence limit to accommodate).
The data for the second part of this exercise are formant values that you will get for estimating two different "perceptual vowel spaces" for these English words. To get these formant values, you need to set up your computer to run the ChooseVowels.tcl script that you can get from the ChooseVowels folder that is linked in at this URL.
If you don't already have tcl/tk on your personal computer, you need to first download and install that programming language. You can get tcl/tk from the ActiveTcl download page on the ActiveState web site. On that page, click on the "Get ActiveTcl" link in the little blue box with the poised-for-jumping frog drawing. Click on the "Free Download" link (or on the button for "Download" in the "Choose your format" part of the page). Click on the "Continue" button on the page that comes up, and then click on the link to the Linux package, the Mac DMG file, or the Windows package, as appropriate for your platform. From there it should be straightforward to install the language. You can test the install if you want by running some of the demos.
Then you need to download the ChooseVowels.tcl script, the associated stimulus files that are zipped up together in the V-all.zip file, the formantList.txt file that specifies the formants for each of the stimuli, and the wordlist.txt file to use as your stimulus list. (You can get these from the ChooseVowels directory that is linked in here.) Put all of these in the same directory. (A good place would be in a directory called ChooseVowels directly under your hard drive.) Extract the 330 vowel stimulus files from V-all.zip, putting them in the same folder where you have the ChooseVowels.tcl script. You are now ready to run the program.
Click on the ChooseVowels.tcl icon, and run it first with yourself as the subject. You may want to specify the file for the results with a file name that identifies these results as being your judgments. Then run the script a second time with your language consultant as the subject. Specify some other file for these results, so that you don't overwrite the first file. Again, you may want to give this file a name that identifies it as the results for your language consultant. (If you are in a group of people who are working with the same language consultant, you only need to make this file once for the whole collective. If you are acting as a consultant for your group, get a second set of files from one of the other members of your group that you then treat as your FPL consultant for the purpose of writing your report.)
If you do not have a personal computer to use, or if you do not want to download and install tcl/tk and the ChooseVowels.tcl script on your computer, or if you are having any trouble at all doing this, ask me right away for help, so that we can arrange a way for you to do this exercise on a different computer or so that I can help you set up your computer.
For each of the participants in the experiments (i.e., yourself and the language consultant), make a plot of the production vowel space in ERB space, with a plot of the perceptual vowel space overlaid. You can use the h_dVowels.R script to do this. Note: If you use the lines() command, you will want to order the lines in the input files to match the progression around the edge of the vowel space, and you will need to modify the lines that specify what file to read in your results from, to match the names of the files that contain the results. Also, this script assumes you have edited the results from running the ChooseVowels.tcl program so that the spaces and file name have been replaced by a tab and your transcription. The apostrophe also needs to be taken out of the word who'd, so that your file should look something like this file in the scripts folder. Your report should include your methods section from Part 1, a results section which is the two figures, and a short (no more than two short paragraphs) discussion section.
In the first paragraph of the discussion section, you should note the patterns that you see in each plot, discussing the relationship between the production space and the perceptual space. Speculate about any gross discrepancies. Can these be attributed to the difference in vocal tract size between the subject and the perceived speaker of the ChooseVowels.tcl stimuli?
In the second paragraph of the discussion section, you should compare across the two figures. What differences do you see? Choosing the most salient one of the differences discuss it in terms of the different first languages that you and the language consultant speak?