This chapter reports a second study on perceptual discrimination of speech quality change under simultaneously changing speech content. The results imply that double changes in quality and content are discriminated significantly faster than single quality changes, presumably because of higher perceptual salience of the former relative to the latter. Neural indication of quality change may be “attentionally masked” by concurrent content change, as the latter possessed a relatively higher informativeness or informational value than the former, involving additional variation in semantic meaning beyond mere variation in perceived form.