Acoustic intensity measurements with Swallow floats


  • F. Desharnais SACLANTCEN, La Spezia, Italy
  • G.L. D'Spain


acoustic intensity measurement, hydrophones, underwater sound, Swallow float, hydrophone, acoustic pressure, geophones, particle velocity


A Swallow float is a deep water drifting float that contains four acoustic sensors: one hydrophone that measures acoustic pressure and three orthogonal geophones that measure particle velocity in three dimensions. Each unit is free-floating, and also contains: a compass to derive the true heading of the float, all the data recording hardware, a ballast to control the float depth, and a high-frequency transducer for communication between the float and a nearby receiver. The advantages presented by the Swallow floats are two-fold: first, the free floating ability reduces the flow noise to a minimum, producing very good quality data down to 0.5 Hz; second, the information from the four sensors can be combined to give measurements of vectorial acoustic intensity. Only one float is therefore needed to obtain both the magnitude and the directionality of the ambient noise field at one point in space

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How to Cite

Desharnais F, D’Spain G. Acoustic intensity measurements with Swallow floats. Canadian Acoustics [Internet]. 1994 Sep. 1 [cited 2024 Apr. 23];22(3):159-60. Available from:



Proceedings of the Acoustics Week in Canada