A recent innovation in the musical field has been the introduction of drum heads made of sheet Mylar plastic. This investigation reports the acoustical differences found in heads made of the two materials. Two types of drums were chosen, the bass drum and the field drum. Two identical drums of each type were fitted with heads, and investigations were made for several tension adjustments. A professional drummer was engaged to adjust and play these drums and a professional quality tape recording was made of their sounds, including single impact beats and steady rolls. These tape recordings were then analyzed in the laboratory. The average acoustical spectra of the drums were determined in half octave bands (similar to the method of Sivian, Dunn, and White), using the quasi‐steady‐state sound of the roll. The peak sound level spectra were also obtained using the General Radio impact sound analyzer. A further analysis was made of the buildup and decay of the drum sounds in chosen frequency bands using a high speed graphic level recorder. The analysis of the test results shows that under certain operating conditions there are considerable differences in the performance of the two kinds of heads. These differences correlate with subjective reactions. The chief physical differences are: (1) the calfskin drum head is capable of a much larger range of tension adjustment, and (2) under certain conditions it has more damping. When the bass drum is tuned to concert tightness, there is a significant difference in the two spectra and in the time variation of intensity. In the field drum there is little spectral difference, but the calfskin gives a more staccato beat with less “metallic” ringing.