Synchronizing Video, Ultrasound, and Audio with a Water Balloon

Synchronization complicates the use of ultrasound in phonetics research, particularly with methods that incorporate video data of external reference points (e.g., [3, 4]). The challenge of a third stream is compounded in longer spans of data at higher than NTSC standard frame rates. As part of work toward developing high-speed ultrasound techniques for long spans of running speech, this paper proposes using a water balloon to create a common analogue, non-speech reference event across tri-modal data. ‘Snapping’ the tied end of the balloon on camera while holding its base against an ultrasound transducer results in a synchronous optical and acoustic event. This allows for the validation of otherwise synchronized data as well as the alignment of otherwise unsalvageable, misaligned data. Using a water balloon clacker-board immediately before a span of interest potentially allows that immediate span to be synchronized to the point of analytical viability.