A new type of air-gun has been developed that has a greatly reduced acoustic output at high frequencies. The high frequencies originate from the rising edge of the primary pulse; the reduction has been achieved by a significant redesign of the mechanism that controls the air release.

The environmental benefit of such a source is demonstrated and it is shown that the pulse-shape within the seismic imaging frequency range is substantially unaffected.

The recently released ‘Draft Guidance for Assessing the Effects of Anthropogenic Sound’ from the National Oceanic and Atmospheric Administration (NOAA, 2013) with its more stringent requirements on high-frequency sound has drawn this issue into a sharper focus.

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