A Paradoxical Aspect of Auditory Change Detection

Enhancing a tone by shifting its frequency or intensity

“…The fact that a frequency shift between two tones could be heard even when the first tone was not audible individually provided evidence for the existence of automatic FSDs. Subsequent studies confirmed that suggestion and specified the properties of the FSDs (Demany and Ramos, 2007;Demany et al, 2008Demany et al, , 2009Demany et al, , 2010Demany et al, , 2011Cousineau et al, 2009;Carcagno et al, 2011). It was shown by Demany et al (2011) that the FSDs are essentially insensitive to the presence of a wideband noise burst between two tones.…”

“…It was shown by Demany et al (2011) that the FSDs are essentially insensitive to the presence of a wideband noise burst between two tones. Demany and Ramos (2007) and Carcagno et al (2011) measured performance in the up/ down task using monaural chords and test tones which were presented either to the same ear or contralaterally. They found that performance was barely poorer in the latter case than in the former case (d' decreased by 8.9%, on average), and they concluded that the FSDs are essentially insensitive to ear of input.…”

“…We reasoned that if intensity enhancement were mainly based on neural adaptation, the noise could be deleterious to this form of enhancement since it should produce nonselective adaptation of frequency-selective neurons. On the other hand, under the assumption that frequency enhancement is mainly an accomplishment of the FSDs, previous results which will be described below (Demany and Ramos, 2007;Demany et al, 2011) led to the prediction that the noise would have little effect on this form of enhancement. In experiment 3, the precursor and test chords used on a given trial were presented either to the same ear or to opposite ears.…”

“…The literature suggested that, in the latter case, intensity enhancement would not be observed. On the other hand, under the assumption that the FSDs are instrumental in frequency enhancement, it could be expected that frequency enhancement would be barely reduced when the precursor and test chords are presented to opposite ears rather than to the same ear (Demany and Ramos, 2007;Carcagno et al, 2011).…”