Show Reference: "A localization algorithm based on head-related transfer functions"

A localization algorithm based on head-related transfer functions The Journal of the Acoustical Society of America, Vol. 123, No. 6. (June 2008), pp. 4290-4296 by Justin A. Macdonald
@article{macdonald-2008,
    abstract = {Two sound localization algorithms based on the head-related transfer function were developed. Each of them uses the interaural time delay, interaural level difference, and monaural spectral cues to estimate the location of a sound source. Given that most localization algorithms will be required to function in background noise, the localization performance of one of the algorithms was tested at signal-to-noise ratios ({SNRs}) from 40 to -40 {dB}. Stimuli included ten real-world, broadband sounds located at 5 degrees intervals in azimuth and at 0 degrees elevation. Both two- and four-microphone versions of the algorithm were implemented to localize sounds to 5 degrees precision. The two-microphone version of the algorithm exhibited less than 2 degrees mean localization error at {SNRs} of 20 {dB} and greater, and the four-microphone version committed approximately 1 degrees mean error at {SNRs} of 10 {dB} or greater. Potential enhancements and applications of the algorithm are discussed.},
    author = {MacDonald, Justin A.},
    citeulike-article-id = {13445817},
    citeulike-linkout-0 = {http://view.ncbi.nlm.nih.gov/pubmed/18537380},
    citeulike-linkout-1 = {http://www.hubmed.org/display.cgi?uids=18537380},
    issn = {1520-8524},
    journal = {The Journal of the Acoustical Society of America},
    keywords = {hrtf, ssl},
    month = jun,
    number = {6},
    pages = {4290--4296},
    pmid = {18537380},
    posted-at = {2014-11-26 13:35:52},
    priority = {2},
    title = {A localization algorithm based on head-related transfer functions},
    url = {http://view.ncbi.nlm.nih.gov/pubmed/18537380},
    volume = {123},
    year = {2008}
}

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The way sound is shaped by the head and body before reaching the ears of a listener is described by a head-related transfer function (HRTF). There is a different HRTF for every angle of incidence.

MacDonald proposes two methods for sound source localization based on head-related transfer functions (actually the HRIR, their representation in the time domain).

The first method for SSL proposed by MacDonald applies the inverse of the HRIR $F^{(i,\theta)}$ to the signal recorded by $i$ For each microphone $i$ and every candidate angle $\theta$. It then uses the Pearson correlation coefficient to compare the resultant signals. Only for the correct angle $\theta$ should the signals match.

The second method for (binaural) SSL proposed by MacDonald applies the HRIR $F^{(o,\theta)}$ to the signals recorded by the left and right microphones every candidate angle θ, where $F^{(o,\theta)}$ is the respective opposite microphone. It then uses the Pearson correlation coefficient to compare the resultant signals. Only for the correct angle θ should the signals match.

The binaural sound-source localization methods proposed by MacDonald can be extended to larger arrays of microphones.