Threshold received sound pressure levels of single 1-2 kHz and 6-7 kHz up-sweeps and down-sweeps causing startle responses in a harbor porpoise (Phocoena phocoena).
J Acoust Soc Am
; 131(3): 2325-33, 2012 Mar.
Article
em En
| MEDLINE
| ID: mdl-22423727
ABSTRACT
Mid-frequency and low-frequency sonar systems produce frequency-modulated sweeps which may affect harbor porpoises. To study the effect of sweeps on behavioral responses (specifically "startle" responses, which we define as sudden changes in swimming speed and/or direction), a harbor porpoise in a large pool was exposed to three pairs of sweeps a 1-2 kHz up-sweep was compared with a 2-1 kHz down-sweep, both with and without harmonics, and a 6-7 kHz up-sweep was compared with a 7-6 kHz down-sweep without harmonics. Sweeps were presented at five spatially averaged received levels (mRLs; 6 dB steps; identical for the up-sweep and down-sweep of each pair). During sweep presentation, startle responses were recorded. There was no difference in the mRLs causing startle responses for up-sweeps and down-sweeps within frequency pairs. For 1-2 kHz sweeps without harmonics, a 50% startle response rate occurred at mRLs of 133 dB re 1 µPa; for 1-2 kHz sweeps with strong harmonics at 99 dB re 1 µPa; for 6-7 kHz sweeps without harmonics at 101 dB re 1 µPa. Low-frequency (1-2 kHz) active naval sonar systems without harmonics can therefore operate at higher source levels than mid-frequency (6-7 kHz) active sonar systems without harmonics, with similar startle effects on porpoises.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Limiar Auditivo
/
Som
/
Reflexo de Sobressalto
/
Phocoena
Limite:
Animals
Idioma:
En
Revista:
J Acoust Soc Am
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Holanda