Taygete: A 3D Surround Sound Headset
Directional hearing for humans has different principles at its base. One is the interaural time difference (ITD), where the time difference between soundwaves that reach the ear holds directional information. The second principle is the interaural level difference (ILD), where the sound pressure level difference holds directional information. The third principle is the frequency shaping (transfer function) that the pinna and head shape apply to sound sources from different directions. These head-related transfer functions (HRTF’s) are highly individual. While ITD and ILD can be synthesized with moderate effort, HRTF’s cannot be generalized, due to their individual nature.
The CUE preserving headphone aims at maintaining these directional cues, by positioning small drivers around the listener’s ear. Based on this concept, USound developed a 3D headphone reference design.
The CUE preserving principle
CUE preserving headphones enhance directional hearing. This is achieved by fitting multiple small drivers inside a headphone. They are placed, so that emitted sound from each of them will reach the ear from a different direction, thus keeping the natural directional information (the cues) of the human hearing apparatus.
The Adap MEMS speaker is especially suitable to apply this principle in a headphone, due to its compact size of 6.7 x 4.7x 1.58 mm. This allows usage of multiple speakers in a compact volume, which improves distinctly the directional impression of the headphone. Besides that, a two-way audio solution is used, where an electrodynamical woofer and the MEMS tweeters are combined. The MEMS tweeters showing no membrane modes at high frequencies, which improves the acoustic performance at high frequencies in terms of non-linear distortions.
The Taygete 4.0 headphones
The Taygete 4.0 headphone consists of a headband, two custom-built earcups and the built-in electronics. The two earcups each include a 40 mm dynamic driver that is used for reproducing signals in the lower frequency range (below 2kHz) and 16 MEMS speakers that reproduce the high-frequency content which is most relevant for directional hearing.
- 16 high-performance built-in MEMS and a woofer in each cup
- Possibility of stereo enhancement, elevation experiments, sound source positioning, surround mapping for 5.1 and 7.1 and other audio formats
- An algorithm that enables real-time 3D sound
- USB-C interface