| 摘要 |
<p>A variable high-pass filter (VHPF) (20) can be altered in its cut-off frequency (fc), for which purpose it has a controlling input where a control signal can be applied to alter the cut-off frequency. A low-pass filter (10) feeds an audio signal for improvement to the VHPF and an input terminal (1) sets up the audio signal. At the output of the VHPF there is an amplifier stage (30) to amplify the output signal from the VHPF by a factor (g) between 1.5 and 4.</p> |
