Vertical Stereophonic Localization in the Presence of Interchannel Crosstalk: the Analysis of Frequency-Dependent Localization Thresholds

Audio engineers are increasingly looking to improve the spatial experience of surround sound by including loudspeakers in the vertical domain, so-called height channels. Listening tests were conducted to investigate the frequency dependency of localization thresholds on vertical interchannel crosstalk. The effect of frequency on localization was significant: thresholds were highest at low frequencies (-5.3 dB at 125 Hz and -3.03 dB at 250 Hz), falling to between -9 dB and -10.5 dB as the frequency increased beyond 1000 Hz. When configuring 3D microphone arrays, cardioid microphones would be a more appropriate choice for the height layer than omnidirectional microphones with regard to localizing source images near the main loudspeaker layer position. To better create a vertical phantom image, different localization thresholds could be applied to different frequency bands of the height channel signal. Control of localization thresholds can be achieved by manipulating the levels of single-octave bands within the height-channel signal rather than by manipulating the signal as a whole.