Achieving fluid, native-quality speech in a second language is difficult task for adult learners. For several years, I’ve used Dr. Olle Kjellin’s method of “chorus repetition” for my Russian language study. In this post, I’m presenting a method for scripting Audacity to facilitate the development of audio source material to support his methodology.

Background

For detailed background on the methodology, I refer you to Kjellin’s seminal paper “Quality Practise Pronunciation with Audacity - The Best Method!" on the subject of chorus repetition practice. The first half of the paper outlines the neurophysiologic rational for the method and the second half describes the practical use of the cross-platform tool Audacity to generate source material for this practice.

Rationale for this project

Preparing source material (sentences of about 2 seconds duration) for this method is not difficult, but the steps are repetitive. Fortunately Audacity offers the ability to script its behaviour through macros (Tools → Macros...). Two macros are described here. Neither are complex, but they do chain common commands in Audacity, making it faster to produce material for chorus repetition. The first macro just trims silence from the clip and compresses its dynamic range. The second takes a clip, ideally a single sentence, adds 0.65 seconds of silence at the end, then replicates the clip + the silence 5 times for a total of 6 repetitions.

Macros

Truncate and compress

Num	Command	Parameters
01	Select All
02	Truncate Silence	Action=“Truncate Detected Silence” Compress=“50” Independent=“0” Minimum=“0.5” Threshold="-20” Truncate=“0.5”
03	Compressor	AttackTime=“0.2” NoiseFloor="-40" Normalize=“1” Ratio=“2” ReleaseTime=“1” Threshold="-12" UsePeak=“0”

To install this macro, download the file (Download ZIP.) On macOS, you can move the file to ~/Application Support/audacity/Macros. I’m not sure where it goes on other platforms; check the manual.

To use the macro, start with the sentence clip you want to process and invoke Tools → Apply Macro → TruncateAndCompress.

You can play around with different parameters if you need to trim more or less silence or if you want to change the compressor settings.

Kjellin Sentences

This macro will take a prepared clip, ideally a single sentence and create six total iterations with 650 ms of silence between each iteration.

Num	Command	Explanation
01	SelEnd:	Move the selection point to the end
02	Select:End="-0.65" Mode=“Set” RelativeTo=“SelectionEnd” Start=“0”	Create an empty 0.65 second region
03	Silence:Use_Preset=“User Preset:650ms”	Add 0.65 seconds of silence
04	SelectAll:	Select the original clip + the silence
05	CursSelEnd:	Move the cursor to the end of the new selection
06	Repeat:Count=“5”	Repeat 5 times for a total of six iterations on the track.

To install the macro, download it from the following location using Download ZIP, decompress and place in the Macros directory as above.

You will need one additional step before this is usable. You will need to create a user preset for the Generate silence tool. Navigate to Generate → Silence... and create a preset named “650ms” so that the macro can use it.

Again, to use it, just prepare a track with a single sentence you wish to use and then Tools → Apply Macro → KjellinSentences.

Enjoy and keep practicing!