, Volume 99, Issue 9, pp 767–771 | Cite as

Stereotypical rapid source level regulation in the harbour porpoise biosonar

  • Meike LinnenschmidtEmail author
  • Laura N. Kloepper
  • Magnus Wahlberg
  • Paul E. Nachtigall
Short Communication


Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8 m distance in a go/no-go paradigm. On-axis clicks had source levels of 145–174 dB re 1 μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4 m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100 ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.


Automatic gain control Target detection Hydrophone array Click train Biosonar 



This study was funded by the Danish Council for Independent Research, the Faculty of Natural Science at the University of Southern Denmark, its Graduate School ‘SNAK’ and Fjord&Bælt. LNK was funded by ONR grant number #N00014-08-1-1160 issued to PEN and travel was sponsored by the Journal of Experimental Biology Student travel grant. The animals are kept under the permission from the Danish Forest and Nature Agency (J. nr. SN 343/FY-0014 and 1996-3446-0021).


  1. Au WWL, Benoit-Bird KJ (2003) Automatic gain control in the echolocation system of dolphins. Nature 423:861–863PubMedCrossRefGoogle Scholar
  2. Cranford TW, Amundin M, Norris K (1996) Functional morphology and homology in the odontocete nasal complex: implications for sound generation. J Morphol 228:223–285PubMedCrossRefGoogle Scholar
  3. Huggenberger S, Rauschmann MA, Vogl TJ, Oelschlager HHA (2009) Functional morphology of the nasal complex in the harbor porpoise (Phocoena phocoena L.). Anat Rec Adv Integr Ant Evol Biol 292:902–920CrossRefGoogle Scholar
  4. Kloepper LN, Nachtigall PE, Donahue MJ, Breese M (2012) Active echolocation beam focusing in the false killer whale (Pseudorca crassidens). J Exp Biol 215:1306–1312PubMedCrossRefGoogle Scholar
  5. Li S, Nachtigall PE, Breese M (2011) Dolphin hearing during echolocation: evoked potential responses in an Atlantic bottlenose dolphin (Tursiops truncatus). J Exp Biol 214:2027–2035PubMedCrossRefGoogle Scholar
  6. Linnenschmidt M, Beedholm K, Wahlberg M, Højer-Kristensen J, Nachtigall PE (2012) Keeping returns optimal: gain control exerted through sensitivity adjustments in the harbour porpoise auditory system. Proc R Soc B 279:2237–2245Google Scholar
  7. Madsen PT, Johnson M, Aguilar de Soto N, Zimmer WMX, Tyack P (2005) Biosonar performance of foraging beaked whales (Mesoplodon densirostris). J Exp Biol 208:181–194PubMedCrossRefGoogle Scholar
  8. Nachtigall PE, Supin AYa (2008) A false killer whale adjusts its hearing when it echolocates. J Exp Biol 211:1714–1718PubMedCrossRefGoogle Scholar
  9. Nørum U, Brinkløv S, Surlykke A (2012) New model for gain control of signal intensity to object distance in echolocating bats. J Exp Biol. doi: 10.1242/jeb.069427
  10. Popov VV, Ladygina TF, Supin AYa (1986) Evoked potentials of the auditory cortex of the porpoise (Phocoena phocoena). J Comp Physiol A 158:705–711PubMedCrossRefGoogle Scholar
  11. Rasmussen MH, Miller LA, Au WWL (2002) Source levels of clicks from free-ranging white beaked dolphins (Lagenorhinchus albirostris, Gray 1846) recorded in Icelandic waters. J Acoust Soc Am 111:1122–1125PubMedCrossRefGoogle Scholar
  12. Urick RJ (1983) Principles of underwater sound. McGraw-Hill, LondonGoogle Scholar
  13. Verfuß UK, Miller LA, Pilz PKD, Schnitzler HU (2009) Echolocation by two foraging harbour porpoises (Phocoena phocoena). J Exp Biol 212:823–834CrossRefGoogle Scholar
  14. Woods DL, Ridgway SH, Carder DA, Bullock TH (1986) Long-latency auditory event-related potentials in dolphins. In: Schusterman R, Thomas J, Wood R (eds) Dolphin cognition and behaviour: a comparative approach. Hillsdale, New Jersey, pp 61–77Google Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Meike Linnenschmidt
    • 1
    Email author
  • Laura N. Kloepper
    • 2
  • Magnus Wahlberg
    • 1
    • 3
  • Paul E. Nachtigall
    • 2
  1. 1.Institute of BiologyUniversity of Southern DenmarkOdense MDenmark
  2. 2.Hawaii Institute of Marine BiologyUniversity of HawaiiKailuaUSA
  3. 3.Fjord&BæltKertemindeDenmark

Personalised recommendations