Correction: Experience with speech sounds is not necessary for cue trading by budgerigars (Melopsittacus undulatus).

[This corrects the article DOI: 10.1371/journal.pone.

Experience with speech sounds is not necessary for cue trading by budgerigars (Melopsittacus undulatus).

The influence of experience with human speech sounds on speech perception in budgerigars, vocal mimics whose speech exposure can be tightly controlled in a laboratory setting, was measured. Budgerigars were divided into groups that differed in auditory exposure and then tested on a cue-trading identification paradigm with synthetic speech. Phonetic cue trading is a perceptual phenomenon observed when changes on one cue dimension are offset by changes in another cue dimension while still maintaining the same phonetic percept.

Perceptual normalization for speaking rate III: Effects of the rate of one voice on perception of another.

Individuals vary their speaking rate, and listeners use the speaking rate of precursor sentences to adjust for these changes (Kidd, 1989). Most of the research on this adjustment process has focused on situations in which there was only a single stream of speech over which such perceptual adjustment could occur. Yet listeners are often faced with environments in which multiple people are speaking simultaneously.

Effects of syllable-final segment duration on the identification of synthetic speech continua by birds and humans.

In an attempt to test whether experience with or knowledge of language is necessary to show typical speaking rate effects in the perception of speech, budgerigars (Melopsittacus undulatus) and humans categorized stimuli from the synthetic continua /ba/-/wa/ and /bas/-/was/, with both short and long syllable-final phonemes. This comparative approach aims to shed some light on whether knowledge of language has a role in rate normalization effects, such as using duration information as an indicator of speaking rate in human speech perception. Syllable-final phoneme durations were varied, and were either temporally adjacent to the initial target (CV series) or were nonadjacent (CVC series).

Does perceptual learning in speech reflect changes in phonetic category representation or decision bias?

Recent studies show that perceptual boundaries between phonetic categories are changeable with training (Norris, McQueen, & Cutler, 2003). For example, Kraljic and Samuel (2005) exposed listeners in a lexical decision task to ambiguous /s-integral/ sounds in either s-word contexts (e.g.

Do postonset segments define a lexical neighborhood?

Previous research has demonstrated that the number and frequency of lexical neighbors affects the perception of individual sounds within a nonword in a phoneme identification task. In the present research, the issue of what items should be considered part of a word's neighborhood was explored. These experiments, in which both lexical decision and phoneme identification tasks were used, demonstrate that lexical neighborhood effects are not limited to words that match the target item syllable initially (the cohort).

Simple and contingent adaptation effects for place of articulation in stop consonants.

Experiments on selective adaptation have shown that the locus of the phonetic category boundary between two segments shifts after repetitive listening to an adapting stimulus. Theoretical interpretations of these results have proposed that adaptation occurs either entirely at an auditory level of processing or at both auditory and more abstract phonetic levels. The present experiment employed two alternating stimuli as adaptors in an attempt to distinguish between these two possible explanations.

Response organization in selective adaptation to speech sounds.

Previous experiments in speech perception using the selective adaptation procedure have found a shift in the locus of the category boundary for a series of speech stimuli following repeated exposure to an adapting syllable. The locus of the boundary moves toward the category of the adapting syllable. Most investigators have interpreted these findings in terms of feature detector models in which specific detectors are reduced in sensitivity through repeated adaptation.

On the identification of place and voicing features in synthetic stop consonants.

Two models of the interaction of phonetic features in speech perception were used to predict Ss' identification functions for a bi-dimensional series of synthetic CV syllables. The stimuli varied systematically in terms of the acoustic cues underlying the features of place of articulation and voicing. Model I assumed the additivity of phonetic features and their independent processing in perception.