Effects of independent bilateral compressive amplification on lateralization of a single source Ian M. Wiggins and Bernhard U. Seeber MRC Inst. of Hearing Res., Nottingham NG7 2RD, United Kingdom Use of compressive amplification in bilateral hearing aid fittings can disrupt binaural cues important to spatial hearing. The head-related transfer function introduces direction-dependent interaural time and level differences (ITDs and ILDs) which are consistent with one another. Independent bilateral compression, however, reduces ILDs such that they suggest a different, conflicting direction than ITDs. The reduction in ILDs is a dynamic effect that depends on the characteristics of the compression and the sound. Single-channel compression was applied over a wide, high-frequency band. Two conditions were run, with the high-frequency channel presented to listeners in isolation or recombined with an unprocessed low-frequency channel. Stimuli included pink noise bursts with varied onset slopes and rates of amplitude modulation and speech. The effects of compression on the perceived auditory objects were assessed using a semantic differential method, in which listeners rated various spatial attributes on scales between two bipolar adjectives, for example, image width was rated on a scale between “focused” and “diffuse.” Additionally, a lateralization task was performed. Initial results show that for sounds with slow onsets, compression tends to shift image location or causes the image to split. Interestingly, image location can also be affected for speech, particularly if high-pass filtered. PACS: 43.66.Ts http://dx.doi.org/10.1121/1.3384115 J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1811-1811 (March 2010)