Headphones detect direction of sound sources

Researchers at the University of Ulm, Germany, have developed a filter element for headphones, enabling the wearer to distinguish whether an external sound source is approaching from the front or back. The filter element helps locate external sound sources or general noises in the vertical plane and can prevent dangerous situations.

Any acoustic object in the wearer’s surroundings can be located precisely with this filter element, especially acoustic objects in the wearer’s ‘blind spot’.

The problem is that when wearing headphones and playing back sounds, the wearer’s ability to perceive sounds in the surrounding environment is significantly limited. It is difficult or even impossible to determine whether an external sound source is approaching from the front or back. With the filter element external sound can be processed in the wearer’s ears.

The element is arranged around the microphone input on the outside of the headphones, just like human hearing. It reduces sound ambiguities from different directions, especially from vertical directions, regardless of their spectral composition.

The outside of the filter element has specifically shaped structures that change external sound into its spectral composition, just as the human ear does, so that spatially dependent frequency modulations occur. These filter elements can be incorporated into all types of headphones, including around-the-ear and over-the-ear models, in-ear headphones, headsets, and bone conduction headphones in order to prevent ‘front-back confusion’.

Patents for the invention have been applied for in Germany and various European countries.

Image caption: Sketch of a possible headphone prototype with the innovative filter element. In this example, the shaped structures (protrusions) share the natural shape of the human ear, but other designs are also possible. ©Timo Oess.