Working in Praat

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# Working in Praat
## Measuring VOT
### Joseph V. Casillas, PhD
### Rutgers University</br>Last update: 2020-10-22

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# About Praat

<p></p>

- Praat is a free, cross-platform program used in linguistics for
  - speech analysis, synthesis, and manipulation
  - labeling and segmentation
  - listening experiments
  - statistics
- Download [here](http://www.praat.org)

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# Overview

### In this tutorial you will learn about:

- Voice Onset Time (VOT)

</br>

### You will learn how to:

- Measure VOT in word initial stops
- Create graphics with waveforms/spectrograms and time segmentations

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# Voice onset time

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# Voice onset time

- Measurement (in ms) associated with stop consonants
- One of several acoustic correlates of voicing contrasts (i.e. 'bin' vs. 'pin')
- Result of coordination of gestures
- <BLUE>Time interval (in ms) between the release of the stop burst and the onset of voicing</BLUE>

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# Types of VOT

### Three phonetic realizations of voicing

- **Lead** (negative) VOT: voicing begins before release of stop (approx. -60ms)
- **Short-lag** (positive) VOT: short time interval after release of stop before onset of voicing (0ms to 30ms)
- **Long-lag** (positive) VOT: longer time interval after release of stop before onset of voicing (approx. 60ms)

### Cross-linguistic differences

- What constitutes a phonologically voiced or voiceless stop is language-specific
- Average VOT values vary depending on language, speaker, phonetic context, etc.
- That said, they typically fall in a variety-specific range

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# Cross-linguistic differences

### English VOT

- English has a two-way voicing contrast 
	- Phonologically voiced stops realized with **short-lag** VOT
	- Phonologically voiceless stops realized with <BLUE>long-lag</BLUE> VOT

### Spanish VOT

- Spanish has a two-way voicing contrast
	- Phonologically voiced stops realized with **lead** VOT
	- Phonologically voiceless stop realized with <BLUE>short-lag</BLUE> VOT

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# Spanish vs. English

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# Measuring VOT

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# Measuring VOT

- VOT: .blue[Time interval (in ms) between the release of the stop burst and the onset of voicing]
- In the spectrogram/waveform we need to locate 2 landmarks:
  - (1) stop release 
  - (2) voicing onset 
- `Time in ms between (1) and (2) = VOT`

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# Measuring VOT

### English voiced stop (/d/ 'damper')

- (1) stop release 
- (2) voicing onset 
- `Time in ms between (1) and (2) = VOT`

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# Measuring VOT

### English voiceless stop (/t/ 'taboo')

- (1) stop release 
- (2) voicing onset 
- `Time in ms between (1) and (2) = VOT`

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# Measuring VOT

### Spanish voiced stop (/b/ 'bala')

- (1) stop release 
- (2) voicing onset 
- `Time in ms between (1) and (2) = VOT`

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# Measuring VOT

### Spanish voiceless stop (/p/ 'pala')

- (1) stop release 
- (2) voicing onset 
- `Time in ms between (1) and (2) = VOT`

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<p></p>

- When you select the voicing onset and the stop release, Praat will automatically give you the 
time interval
- The VOT is 64ms for this particular English /p/ (long-lag VOT)

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# Practice

### English

- Create recordings of the words 'bin' and 'pin' in English
- Examine the waveforms and spectrograms
- Measure their VOT

### Spanish

- Download the following files
	- [bata](https://www.jvcasillas.com/praat/site_libs/assets/wavs/bata_sp.wav) 
	<img width='20' src="../../site_libs/assets/img/fill.png">
	<audio controls>
      <source src="../../site_libs/assets/wavs/bata_sp.ogg" type="audio/ogg">
      <source src="../../site_libs/assets/wavs/bata_sp.wav" type="audio/mpeg">
      Your browser does not support the audio element.
    </audio>
	- [pata](https://www.jvcasillas.com/praat/site_libs/assets/wavs/pata_sp.wav) 
	<img width='20' src="../../site_libs/assets/img/fill.png">
	<audio controls>
	  <source src="../../site_libs/assets/wavs/pata_sp.ogg" type="audio/ogg">
	  <source src="../../site_libs/assets/wavs/pata_sp.wav" type="audio/mpeg">
	Your browser does not support the audio element.
	</audio>
- Import them into Praat
- Examine the waveforms and spectrograms
- Measure their VOT

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# Creating graphics

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# Creating graphics

- **No screenshots**
- Praat has exceptional graphing capabilities

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# Step by step approach to plotting VOT in Praat

### (1) Select sound object you want to graph

### (2) Click `View and Edit`

### (3) Select desired region of recording > zoom in (`sel`)

### (4) Select VOT range (stop release to onset of voicing)

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# Step by step approach to plotting VOT in Praat

### (5) Draw waveform

- `File` > `Draw visible sound...`
- Unselect `Draw selection times` and `Garnish`
- Click Ok

**Note**: You may have to erase (Edit > Erase all) and reselect the viewport. 
Try to get yours to look like this and redo step 5 as necessary

### (6) Once you have a satisfactory waveform, without changing the viewport, select 
the tab `Margins` > `Draw inner box`

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# Step by step approach to plotting VOT in Praat

### (7) Next select a new rectangle in the viewport, just below the waveform

- Try to match yours to the rectangle in the image (use the rulers)

### (8) Draw the spectrogram

- Go back to the spectrogram window
- Select the tab `Spectrum` > `Paint visible spectrogram...`
- Unselect `Erase first` and `Draw selection times`
- Select `Garnish`
- Click Ok

### (9) Select the waveform and the spectrogram in the viewport

### (10) Save as .pdf/.png

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# Step by step approach to plotting VOT in Praat

1. Select sound object you want to graph  
2. Click `View and Edit`
3. Select desired region of recording > zoom in (`sel`)
4. Select VOT range (stop release to onset of voicing)
5. Draw waveform  
	- `File` > `Draw visible sound...`
6. Once you have a satisfactory waveform, without changing the viewport, select 
the tab `Margins` > `Draw inner box`
7. Next select a new rectangle in the viewport, just below the waveform
8. Draw the spectrogram
	- Select the tab `Spectrum` > `Paint visible spectrogram...`
9. Select the waveform and the spectrogram in the viewport  
10. Save as .pdf/.png

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# Conclusion

### In this short tutorial you learned about:

- Voice Onset Time (VOT)

### and now you are able to:

- Measure VOT in word initial stops
- Create graphics with waveforms/spectrograms and time segmentations

### Additional help

- Try another [praat tutorial](http://www.jvcasillas.com/praat/)
- Email me (joseph.casillas@rutgers.edu)