Table 2.

Paired comparisons (Wilcoxon tests) of behavioural and acoustical variables in playback experiments of large adult versus small adult. (NLP, nonlinear phenomena. Formant spacing, from which apparent Vocal tract length (VTL) is directly calculated, is presented in square brackets.)

variable	large adult (means±s.e.)		small adult (means±s.e.)		Z	n	significance
behavioural variables
duration of attention (s)	59.3	8.4	37.7	5.2	−2.063	13	p=0.0391
number of common roars	4.46	1.20	2.79	0.40	−1.179	13	p=0.2384
number of harsh roars	0.69	0.21	0.15	0.09	−2.238	13	p=0.0252
acoustic variables in first response roar
average apparent VTL (cm)	69.0	1.0	66.1	1.7	−1.988	10	p=0.0469
[average formant spacing (Hz)]	254	4	266	7	−2.191	10	p=0.0284
maximum apparent VTL (cm)	72.9	1.2	70.5	1.5	−2.803	10	p=0.0051
[minimum formant spacing (Hz)]	241	4	249	5	−2.803	10	p=0.0051
proportion of responses with NLP	0.72	0.13	0.22	0.13	−2.121	10	p=0.0339