Sennheiser HD 458BT Instruction Manual page 20

Using the headphones
20 | HD 458BT
Information on active noise cancellation
ANC
Due to its closed design, the headphones offer effective passive iso-
lation from ambient noise.
In addition, the headphones have an active noise cancellation (ANC)
function, which allows you to reduce ambient noise to a minimum.
Even when ANC is activated, your headphones' sound quality is
always at its best.
You can activate or deactivate ANC when the headphones and your
audio source are connected via Bluetooth, or the audio cable (pro-
vided that the battery is sufficiently charged).
If you want to create a quiet space in a noisy environment, you can
simply use the headphones – without cable and disconnected from
any Bluetooth device – as noise protection by using ANC (> 20).
Notes on active noise cancellation
• Continuous and uniform noise, such as motor or fan noise, is par-
ticularly well suppressed.
• Speech or high-frequency noise is significantly reduced, but can
remain perceptible.
• In very quiet environments, slight noise may occur. In this case,
deactivate ANC.
• If unusual (whistling or beeping) noise occurs, take the head-
phones off and put them on again. Make sure that the ear cups
properly fit around your ears.
To avoid loud, unusual (whistling or beeping) noise and to ensure
proper noise cancellation, do not cover the microphone openings of
the active noise cancellation circuitry located on the outside of the
ear cups.
Activating/deactivating the active noise
cancellation ANC
To activate the active noise cancellation ANC:
1. Switch the headphones on. Press and hold the on/off button for 2
seconds.
You hear the voice prompt "Power on".
2. Press the on/off button 1x.
The LED flashes purple 3x.
ANC is activated.
To deactivate the active noise cancellation ANC:
▷
Press the on/off button 1x.
The LED flashes purple 3x.
ANC is deactivated.