The calibration of a standard audiometric headset is dependent upon headband tension. Similarly the attenuation provided by this standard, supra‐aural headset is dependent upon the headband tension, and headband tension may change observably during clinical use. This is especially pertinent when one considers that masking from background noise is a serious problem when hearing levels are measured at or near the low reference threshold levels specified in the American National Standards Specifications for Audiometers, ANSI S3.6‐1969. In the present study the degree of headband tension change during clinical threshold audiometry has been measured empirically. In addition the effect of these tension changes upon the obtained pure‐tone thresholds at several frequencies were determined. Significant differences in obtained thresholds contingent upon deterioration of headband tension were noted. Results of this experiment will be discussed by reference to modeling of the acoustic impedance characteristics of a simple, single‐cavity audiometric headset.