Adjustable audiometer for level and frequency thresholds - has distortion equaliser formed by bridged element with lengthwise resistors and transverse impedance

摘要

The audiometer has adjusting elements for various frequencies and/or levels, together with headphones transmitting the noise to the person whose hearing is being tested. A distortion equaliser between the final amplifier and the headphones smooths the free-transmission constant. The equaliser is a bridged T-unit with a first lengthwise resistor (30) followed by a transverse impedance. The system includes a second resistor (31), a capacitor (32) and an inductance (33), together with a second lengthwise resistor are bridged by a parallel circuit consisting of a resistor (36), an inductance (37) and a capacitor (35). The frequency range is selectable between 100Hz and 10KHz. Sine audio generators of low distortion may form the signal sources.