Sound localization in noise in normal-hearing listeners

Area of Science:

• Auditory perception
• Psychoacoustics
• Spatial hearing

Background:

• Accurate sound localization is crucial for navigating and interacting with the environment.
• Auditory spatial cues, such as interaural time differences and interaural level differences, are vital for localization.
• The presence of masker noise can degrade localization performance, particularly in challenging acoustic conditions.

Purpose of the Study:

• To investigate the impact of masker characteristics on the ability to localize sound in the frontal-horizontal plane.
• To examine how signal frequency content, signal-to-noise ratio (S/N), and masker location influence localization accuracy.
• To determine the relative contribution of low- and high-frequency auditory cues for sound localization in noise.

Main Methods:

• Normal-hearing listeners localized click trains in quiet and with a white-noise masker.
• Stimuli were presented under broadband, low-pass, and high-pass filtering conditions.
• Masker locations varied across azimuth (-90, 0, +90 degrees), with multiple signal-to-noise ratios tested.

Main Results:

• Localization accuracy remained stable until signal-to-noise ratios of 0-6 dB, then decreased with more adverse ratios.
• Localization was more affected by noise at +/- 90 degrees azimuth compared to 0 degrees azimuth.
• Low-frequency cues were less resistant to noise than high-frequency cues when the masker was lateralized.

Conclusions:

• Low-frequency auditory cues are more vulnerable to masking noise, especially when the noise source is spatially separated from the target.
• Listeners prioritize high-frequency cues for sound localization when both low- and high-frequency information is available and reliable.
• Reduced signal detectability in the ipsilateral ear may contribute to impaired localization accuracy with lateralized noise.