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M Wahlberg

Publications and source records attributed to M Wahlberg.

4 recordsLinked to original sources
PubMed2002

Sperm whale sound production studied with ultrasound time/depth-recording tags.

Delphinoids (Delphinidae, Odontoceti) produce tonal sounds and clicks by forcing pressurized air past phonic lips in the nasal complex. It has been proposed that homologous, hypertrophied nasal structures in the deep-diving sperm whale (Physeter macrocephalus) (Physeteridae, Odontoceti) are dedicated to the production of clicks. However, air volumes in diving mammals are reduced with increasing ambient pressure, which seems likely to influence pneumatic sound production at depth. To study sperm whale sound production at depth, we attached ultrasound time/depth-recording tags to sperm whales by means of a pole and suction cup. We demonstrate that sperm whale click production in terms of output and frequency content is unaffected by hydrostatic reduction in available air volume down to less than 2% of the initial air volume in the nasal complex. We present evidence suggesting that the sound-generating mechanism has a bimodal function, allowing for the production of clicks suited for biosonar and clicks more suited for communication. Shared click features suggest that sound production in sperm whales is based on the same fundamental biomechanics as in smaller odontocetes and that the nasal complexes are therefore not only anatomically but also functionally homologous in generating the initial sound pulse.

Animals↗
PubMed2000

Sperm whale clicks: directionality and source level revisited.

In sperm whales (Physeter catodon L. 1758) the nose is vastly hypertrophied, accounting for about one-third of the length or weight of an adult male. Norris and Harvey [in Animal Orientation and Navigation, NASA SP-262 (1972), pp. 397-417] ascribed a sound-generating function to this organ complex. A sound generator weighing upward of 10 tons and with a cross-section of 1 m is expected to generate high-intensity, directional sounds. This prediction from the Norris and Harvey theory is not supported by published data for sperm whale clicks (source levels of 180 dB re 1 microPa and little, if any, directionality). Either the theory is not borne out or the data is not representative for the capabilities of the sound-generating mechanism. To increase the amount of relevant data, a five-hydrophone array, suspended from three platforms separated by 1 km and linked by radio, was deployed at the slope of the continental shelf off Andenes, Norway, in the summers of 1997 and 1998. With this system, source levels up to 223 dB re 1 microPa peRMS were recorded. Also, source level differences of 35 dB for the same click at different directions were seen, which are interpreted as evidence for high directionality. This implicates sonar as a possible function of the clicks. Thus, previously published properties of sperm whale clicks underestimate the capabilities of the sound generator and therefore cannot falsify the Norris and Harvey theory.

Animal Communication↗
PubMed1999

Sexual function in women suffering from aortoiliac occlusive disease.

OBJECTIVE: To describe the sexual function in women suffering aortoiliac occlusive disease (AIOD) and in an age-matched reference group. PATIENTS AND METHODS: Thirty-six women suffering from AIOD were included. Twenty were investigated before vascular intervention (untreated) and 16 different women after treatment (treated). Eighteen age-matched women served as a reference group. The patients answered a questionnaire including sexual, social and medical questions and a gynaecological examination was performed. RESULTS: Untreated patients with AIOD have a significantly impaired physical well-being compared to the other groups (p < 0.001). A negative effect of the vascular disease and its treatment on sexual life was experienced by 69% of treated compared to 40% affected among untreated (p = 0.05). Vulval sensibility was impaired in 44% of treated, 11% of untreated and 22% of reference patients. Defective anal sphincter function was found in 33% of treated, 17% of untreated and 6% in the reference group. Those differences were not statistically significant. CONCLUSIONS: Symptomatic AIOD in women is associated with a significantly impaired physical and sexual well-being. Though limited by size and methodology, the results indicate the possibility of iatrogenic nerve damage.

Adult↗