The audio filters have a significant effect on the frequency range of the headphones, and allow you to hear sounds as if your ears were not obstructed even though they are closed off. Because everyone’s hearing is different, two sets of audio filters are included: gray to emphasize mid-range sounds, and black for bass and high frequencies. The audio filters also keep dirt out of the sound tubes. Gray audio filters are fitted as standard.

Before using the headphones, make sure that there are audio filters fitted to the sound tubes, otherwise the headphones will not work properly. Replace the filters if they become dirty or blocked and the headphone sound is affected. Always use the same color of filter for the left and right sound tubes.

Change the audio filters as follows:

1. Remove the ear tips (silicone or foam) by squeezing them together in the center and pulling slowly until they become loose.
2. Carefully push and turn the threaded end of the fitting tool into the used audio filter.
3. Do not over-turn the fitting tool: stop as soon as you feel a slight resistance (about 1 turn), otherwise you will damage the audio filter. Pull out the used filter.
4. You can save the audio filter for later re-use by pushing it into an empty space in the filter box. Remove the fitting tool by twisting it.
5. Discard the audio filter if it is dirty or damaged, and continue by inserting a new filter.
6. Make sure the new filter is positioned in the box with the open side upwards. Press the flat end of the fitting tool into the ring of the filter and pull it straight out. Press the new filter into the sound tube of the headphones. Tilt the fitting tool sideways to and fro to release the filter.