Lenovo Sennheiser User Manual page 15

v If you still cannot hear sound, check to make sure that the headset is
not muted. Under Windows Sound Manager, there is a Mute check
box for speakers (see the figure above for location of mute buttons).
This must be cleared. Many notebook computers (including Lenovo
systems) also have mute buttons that control audio components.
v If you hear your own voice in your headset (sidetone), and want to
disable it, go into Windows Sound Manager, and do the following:
1. Go to Select Options -> Properties.
2. Adjust the volume for playback. Make sure that the microphone
volume control is selected and click OK.
About the Lenovo USB/Analog Headset by Sennheiser
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