We studied the free‐field of external ear canal acoustic impulse responses. The fine structure of the frequency domain characteristics was correlated with the time domain profile of the pinna reflections previously [Hiranaka and Yamasaki, J. Acoust. Soc. Am.73,291–296 (1983)]. A recent measurement with wide band facilities (up to 50 kHz) revealed the fact that the global structure of the frequency response can be correlated with such effects as the head shadow and the pinna direction in a very simple form: the logarithmic amplitude declines almost linearly with linear frequency for all directions of a sound source, and the degree of the declination varies with the direction. In the experiment, impulsive sound source was positioned at nine elevation angles (30°/step) in each of six vertical planes, and 1.5 m from a subject's head. The directional map of the declination (ranging from − 1 dB/10 kHz to − 10 dB/10 kHz) indicated the opening pattern of the pinna. The patterns of such maps from several subjects showed their physical individuality.