This Corrigendum relates to J. Exp. Biol. 215, 1442-1447.
The authors misunderstood JEB's policies on citing non-peer-reviewed literature, and failed to cite the dissertation of Gerstein (Gerstein, 1999), who also measured critical ratios in two captive manatees.
Gerstein measured critical ratios using both pulsed and continuous (4 s) tones in the presence of 1/3-octave wide masking noise using two different noise levels. The critical ratios were lower for the pulsed tones than the continuous tone. Although we did not test the same frequencies, our measurements of critical ratios in two other manatees were similar or lower for similar test frequencies for the continuous tone. For example, we measured critical ratios from two manatees at 4 kHz of 30.8 and 29.9 dB, while Gerstein measured critical ratios at 3 kHz of 31 and 34 dB. At 16 kHz we measured critical ratios of 27.0 and 28.1 dB, while Gerstein measured critical ratios of 38 and 42 dB at 18 kHz. The results Gerstein obtained for the pulsed tones were closer to the critical ratios we measured with the 1 s tone. The differences in results could be due to differences between individuals or methods used in the two studies. They are unlikely to be due to differences in the masking noise, because the bandwidth of masking noise used in our experiments was wider.
The authors apologise to Dr Gerstein, the journal editors and the readership for any inconvenience this may have caused but assure readers that it does not affect the data, results, interpretations or conclusions of the paper.
The journal received a letter of concern relating to a lack of acknowledgement of a previous body of research in J. Exp. Biol. 215, 1442-1447. After contacting the authors of the paper, the journal asked The University of South Florida, USA, to carry out an investigation. The outcome of this investigation indicated no evidence of misconduct.