Figure 4

Correlations between sound characteristics and standard length. Plots of sound characteristics against standard length. Pearson's correlation coefficients and significances are given in graphs. 4A: Segmented linear regression plot SPL against SL, breaking point 57.6 mm SL, regression equations (y = SPL): SL < 57.6 mm: N = 21, SPL = 0.36 SL + 109.76, SL > 57.6 mm: N = 19, SPL = 0.02 SL + 129.10; 4B: Pulse-period (adduction) against SL: N = 40, pulse period = 0.04 SL + 1.93; 4C: Duration of adduction sounds against SL: N = 40, duration = 0.30 SL + 19.59; 4D: Duration of abduction sounds against SL: N = 40, duration = 0.39 SL + 39.69; 4E: Segmented linear regression plot of dominant frequency against SL, breaking point 36.91 mm SL: SL < 36.91 mm: N = 9, dom. freq. = 101.35 SL - 741.89, SL > 36.91 mm: N = 31, dom. freq. = - 7.04 SL + 1469.41; 4F: Segmented linear regression plot bandwidth of sounds 10 dB below SPL of peak frequency against SL, breaking point 73.43 mm SL: SL < 73.43 mm: N = 24, bandwidth = - 53.42 SL + 5174.77, SL > 73.43 mm: N = 11, bandwidth = - 9.36 SL + 2210.15. Regression lines in 4A, 4E and 4F were drawn according to the results of the segmented linear regression calculation. Note two p and r values (one for each regression) in figures 4A, 4E and 4F.