Binaural Technology



  Martin Guski

Binaural technology deals with the generation and reproduction of aurally accurate signals. The ability to differentiate sources from each other or to aurally determine one single signal from a variety of sources has its roots in binaural hearing (hearing with both ears). A well-known example for this is the so-called cocktail party effect. Even in acoustically difficult surroundings (like for example a very busy restaurant) people with normal hearing are able to hold a conversation with one person while at the same time quelling interfering signals (other guests, music the clattering of plates).

The focus of binaural (2-ear) technology is that here both hearing cues which the person receives and processes are physically correctly depicted in order to continue with further experiments on perception and attention, or to be used in other applications (like for example in telephone conferencing).

In order to improve this, both are needed as tools, the acoustic virtual reality for the generation of acoustic scenarios as well as the natural reproduction of acoustic stimuli. The trend in binaural technology goes more and more towards depicting situations in which both can move, the sound source as well as the test person, taking their individual hearing properties into consideration. Using such scenarios numerous experiments can be conducted which will lead to a better understanding of the auditory system. The application areas range from fundamental hearing research to the neuro sciences.

For this we develop measuring and reproduction systems which take the individual properties of a human being in the aural process into consideration.


Artificial Head Technology and Artificial Heads for Children

outer ear transfer functions Fels

There has been little research until now on the connection between a child's growth and the outer ear transmission functions which are essential for spatial hearing. This leads to uncertainty in auditory examinations and the clinical application of head-related processes up to the fitting of hearing aids. The outer ear transmission functions (HRTFs) of children and infants can be calculated with the aid of numeric methods (Boundary Element method, BEM). For that purpose a geometric data base was started with stereo photos (digital photogrammetry) of the head dimensions of children at different ages which enabled evaluation according to different age groups. This will be used for the development of future artificial heads for children.


Individual and individualization of outer ear transfer functions (HRTFs - head-related transfer functions)


The trend in research goes more and more to a correct imaging of complex acoustic sound scenarios which can be used in multiple applications (research areas Acoustic Virtual Reality, Psychoacoustics , Auditory Scene Analysis .

It is our aim to generate an artificially generated acoustic scenario as closely as possible to the human ear. For that all properties that a human being uses in a real scenario should be generated correctly.

In this context we develop measuring technology which will enable us to achieve a set of data of individual HRTFs in high definition and a short measuring time. On the other hand we are working on processes to generate individualized HRTFs. For that a high-resolution HRTF data set is used as a basis which will then be adapted to the individual geometric properties of the test person.