Patent Document ID: 6118875
Application ID: 08700470
Patent Status: 1

Claim One:
1. A method of generating binaural signals by filtering at least one sound input with at least one set of two filters, each set of two filters having been designed so that the two filters simulate the left ear and the right ear parts of a Head-related Transfer Function (HTF), the method having at least one of the following features (a), (b), and (c): (a) the HTF is used generally for a population of humans for which the binaural signals are intended, the HTF being determined in such a manner that the standard deviation of the amplitude, in dB, between subjects is less than a limit selected from the group consisting of limit (i), limit (ii), limit (iii), and limit (iv), wherein: limit (i) is at the most about 1.4 dB between 100 Hz and 1 kHz, and is at the most about 1.4 dB at 1 kHz, linearly increasing, on a logarithmic frequency axis, to about 3.2 dB at 4 kHz, and is at the most about 3.2 dB at 4 kHz, linearly increasing, on a logarithmic frequency axis, to about 6.0 dB at 8 kHz over at least a major part of the frequency interval between 1 kHz and 8 kHz, when determined with pure tones for first angles on and above the horizontal plane of the ears of said humans and on the same side of the ears of said humans; limit (ii) is at the most about 1.4 dB between 100 Hz and 1 kHz, and is at the most about 1.4 dB at 1 kHz, linearly increasing, on a logarithmic frequency axis, to about 2.75 dB at 4 kHz, and is at the most about 2.75 dB at 4 kHz, linearly increasing, on a logarithmic frequency axis, to about 4.5 dB at 8 kHz over at least a major part of the frequency interval between 1 kHz and 8 kHz, when determined with 1/3 octave noise bands for first angles on and above the horizontal plane of the ears of said humans and on the same side of the ears of said humans; limit (iii) is at the most about 1.5 dB between 100 Hz and 1 kHz, and is at the most about 1.5 dB at 1 kHz, linearly increasing, on a logarithmic frequency axis, to about 4.0 dB at 4 kHz, and is at the most about 4.0 dB at 4 kHz, linearly increasing, on a logarithmic frequency axis, to about 8.5 dB at 8 kHz over at least a major part of the frequency interval between 1 kHz and 8 kHz, when determined with pure tones for all angles other than said first angles; and limit (iv) is at the most about 1.5 dB between 100 Hz and 1 kHz, and is at the most about 1.5 dB at 1 kHz, linearly increasing, on a logarithmic frequency axis, to about 3.0 dB at 4 kHz, and is at the most about 3.0 dB at 4 kHz, linearly increasing, on a logarithmic frequency axis, to about 5.5 dB at 8 kHz over at least a major part of the frequency interval between 1 kHz and 8 kHz, when determined with 1/3 octave noise bands for all angles other than said first angles; (b) the duration of the time domain representation of the transfer function of the filter simulating the HTF is at the most 2 msec; and (c) the value at zero Hertz of the frequency domain description of the transfer function of the filters simulating the HTF is in the range from 0.316 to 3.16.