Last semester, I wanted to show my students the turbulences in the air around the mouth during articulation. Unfortunately, I was not able to find any video material which could nicely illustrate such effects. We therefore started a cooperation with the “Deutsches Zentrum für Luft und Raumfahrt” in Lampoldshausen. Together with Friedolin Strauss from the DLR, Denis Arnold, Tino Sering and myself, we recorded a total of 45 seconds of speech using a schlieren photography captured by a high speed camera.
You might be wondering: “Why only 45 seconds of speech?” Well, the camera recorded with a sampling rate of 10 000 frames per second. After recording roughly 5 seconds of speech, the system had to upload the data (20-30Gb) to the server. This took around 30 Minutes. In total, we spend four hours of recording and, as you can see, shooting nice pictures.
Schlieren photography allows you to track changes in the density changes of a medium, in our case of the air. With a temporal resolution of 100 microseconds (0.1 milliseconds), the camera allows us to investigate subtle changes in the airflow out of the mouth and out of the nose. We saw effects we have not anticipated before already in the screening of the material. We are looking forward to the analysis, once the data will be on our servers.
If you want to know more about our visit to Lampoldshausen, the DLR published a blog post here (in German).