Measured vs Modeled HRTF's

Because HRTF's are so complex, many spatial audio systems have depended on using experimentally measured data, such as the KEMAR data that we showed earlier. However, the primary reason for using HRTF's is to capture elevation as well as azimuth effects, and elevation cues are particularly sensitive to individual differences. Four different approaches have emerged:
  1. Use a compromise, standard HRTF. This will give rather poor elevation results for some percentage of the population, but it is all that is practical for inexpensive systems. To date, neither the IEEE, the ACM nor the AES has defined a standard HRTF, but it looks like a company such as Microsoft or Intel will create a de facto standard.

  2. Use one of a set of standard HRTF's. This requires measuring the HRTF's for a small number of people who represent distinctly different population modes, and providing a simple way for a user to select the one that fits best. Although this has been proposed, no such set of standard HRTF's currently exists.

  3. Use an individualized HRTF. This requires measuring the listener's HRTF, which is an inconvenient and time-consuming procedure. However, it produces excellent results.

  4. Use a model HRTF containing parameters that can be adapted to each individual. This is the option that we explore next.

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