Miscellaneous

3D Audio in bandwidth-limited communication systems

Most communication systems, e.g. intercom radio systems, are not capable of transferring speech at full bandwidth. The audio quality may also be decreased by heavy compression, e.g. to a 2 kbps bit rate.

AM3D has tailored a 3D Audio engine specifically for this application, which provides excellent sound separation and 'out of head' experience. The engine can be combined with similar early warning system, i.e. alarm at high sample rates. At low sample rates (8 kHz), the engine has ultra low MIPS usage. The solution can be used with existing stereo audio ancillaries/headsets with/without ANR.

High resolution generic HRTF database based on artificial head

Based on comprehensive studies of human acoustic properties, the most advanced non-individual HRTF-database has been developed. The HRTFs of this generic database are measured on AM3D's state-of-the-art artificial head - named Valdemar - with a spherical resolution of 2°. The HRTF database is unsurpassed in resolution as well as in localisation performance. This high-performance 3D audio technology makes it useful for mission-critical systems in the military industry where precision is of the utmost importance.

Best-performing human HRTF database selected from 40 different human HRTF databases

AM3D's non-individual human HRTF database is established on basic of the best-performing database of a set of 40 different individual HRTF databases. The performance is found by comprehensive subjective testing of localisation accuracy, where each individual listens with another individual's 'ears'. The performance is influenced by the match between the individual listeners' acoustic properties (HRTFs).

Enhanced localisation performance using head tracker for real-time update of head position

The optimal localisation performance is obtained in a system with real-time updating of the listener's head position, e.g. by a head tracker device. AM3D has combined the 3D Audio engine with several head tracker solutions.

Based on experiments of real and virtual sound sources listening of localisation performance in a system where the listener is wearing a head-tracking device, the localisation uncertainty for virtual sound sources in horizontal plane was found to be near real-life experience, and slightly reduced in vertical plane depending on the angle.

Reduced mental workload

External evaluations between mono audio and 3D audio for mission-critical application concludes that the operator has improved perception of what is being said, follow the sequences of events with more correct, answers on logical and mathematic tests, resulting in a reduced metal workload of up to 20%.