ABSTRACT Deciphering the auditory scene is a problem faced by humans and animals alike. However, ... more ABSTRACT Deciphering the auditory scene is a problem faced by humans and animals alike. However, when faced with overlapping sounds from multiple locations, listeners are still able to attribute the individual sound objects to their individual sound-producing sources. Here, we determined which characteristics of sounds are important for streaming versus segregating in birds. Budgerigars and zebra finches were trained using operant conditioning procedures on an identification task to peck one key when they heard a whole zebra finch song and to peck another when they heard a zebra finch song missing a middle syllable. Once the birds were trained to a criterion performance level on those endpoint stimuli, probe trials were introduced on a small proportion of all trials. The probe songs contained modifications of the incomplete training song's missing syllable. When the bird responded as if the probe was a whole song, it suggests they streamed together the altered syllable and the rest of the song. When the bird responded non-whole song, it suggests they segregated the altered probe from the rest of the song. Results show that some features, such as spectrotemporal similarity and location, are more important for streaming than other features, such as timing.
Journal of the Acoustical Society of America, 2015
ABSTRACT The current project investigates how experience with human speech can influence speech p... more ABSTRACT The current project investigates how experience with human speech can influence speech perception in budgerigars. Budgerigars are vocal mimics and speech exposure can be tightly controlled in a laboratory setting. The data collected include behavioral responses from 30 budgerigars, tested using a cue-trading paradigm with synthetic speech stimuli. Prior to testing, the birds were divided into three exposure groups: Passive speech exposure (regular exposure to human speech), no speech exposure (completely isolated), and speech-trained (using the Model-Rival Method). After the exposure period, all budgerigars were tested using operant conditioning procedures. Birds were trained to peck keys in response to hearing different synthetic speech sounds that began with either “d” or “t.” Sounds varied in VOT and in the frequency of the first formant. Once training performance reached 80% on the series endpoints, budgerigars were presented with the entire series, including ambiguous sounds. The responses on these trials were used to determine which speech cues the birds use, if cue trading behavior was present, and whether speech exposure had an influence on perception. Preliminary data suggest experience with speech sounds is not necessary for cue trading by budgerigars.
The Journal of the Acoustical Society of America, 2013
ABSTRACT Previous work has shown that lexical knowledge (whether a stimulus token makes a word or... more ABSTRACT Previous work has shown that lexical knowledge (whether a stimulus token makes a word or nonword) influences phonetic categorization [e.g., Fox (1984)]. Recent work in our lab examined the effect of lexical influences on speech perception using two tasks (phoneme identification and AXB discrimination) and uncovered some unexpected findings. Listeners who performed identification first showed a robust effect of lexical status on phonetic categorization. However, listeners who performed the discrimination task first showed no effect of lexical status. Since prior research has shown that the lexical effect is fairly robust [see Pitt and Samuel (1993)], the finding that the influence of lexical status can be eliminated by first placing listeners in an AXB discrimination task is the focus of the current research. The AXB task may focus attention on the prelexical, phonetic representation and differences within each phonetic category. This, in turn, eliminates the influence of higher level processes on phonetic perception in the identification task. The present study seeks to replicate this finding and investigate whether other lexical influences on perception (the influence of lexical neighborhood) are also altered by experience with AXB discrimination. Results are discussed in terms of the flow of information during phonetic perception and word recognition.
ABSTRACT Deciphering the auditory scene is a problem faced by humans and animals alike. However, ... more ABSTRACT Deciphering the auditory scene is a problem faced by humans and animals alike. However, when faced with overlapping sounds from multiple locations, listeners are still able to attribute the individual sound objects to their individual sound-producing sources. Here, we determined which characteristics of sounds are important for streaming versus segregating in birds. Budgerigars and zebra finches were trained using operant conditioning procedures on an identification task to peck one key when they heard a whole zebra finch song and to peck another when they heard a zebra finch song missing a middle syllable. Once the birds were trained to a criterion performance level on those endpoint stimuli, probe trials were introduced on a small proportion of all trials. The probe songs contained modifications of the incomplete training song's missing syllable. When the bird responded as if the probe was a whole song, it suggests they streamed together the altered syllable and the rest of the song. When the bird responded non-whole song, it suggests they segregated the altered probe from the rest of the song. Results show that some features, such as spectrotemporal similarity and location, are more important for streaming than other features, such as timing.
Journal of the Acoustical Society of America, 2015
ABSTRACT The current project investigates how experience with human speech can influence speech p... more ABSTRACT The current project investigates how experience with human speech can influence speech perception in budgerigars. Budgerigars are vocal mimics and speech exposure can be tightly controlled in a laboratory setting. The data collected include behavioral responses from 30 budgerigars, tested using a cue-trading paradigm with synthetic speech stimuli. Prior to testing, the birds were divided into three exposure groups: Passive speech exposure (regular exposure to human speech), no speech exposure (completely isolated), and speech-trained (using the Model-Rival Method). After the exposure period, all budgerigars were tested using operant conditioning procedures. Birds were trained to peck keys in response to hearing different synthetic speech sounds that began with either “d” or “t.” Sounds varied in VOT and in the frequency of the first formant. Once training performance reached 80% on the series endpoints, budgerigars were presented with the entire series, including ambiguous sounds. The responses on these trials were used to determine which speech cues the birds use, if cue trading behavior was present, and whether speech exposure had an influence on perception. Preliminary data suggest experience with speech sounds is not necessary for cue trading by budgerigars.
The Journal of the Acoustical Society of America, 2013
ABSTRACT Previous work has shown that lexical knowledge (whether a stimulus token makes a word or... more ABSTRACT Previous work has shown that lexical knowledge (whether a stimulus token makes a word or nonword) influences phonetic categorization [e.g., Fox (1984)]. Recent work in our lab examined the effect of lexical influences on speech perception using two tasks (phoneme identification and AXB discrimination) and uncovered some unexpected findings. Listeners who performed identification first showed a robust effect of lexical status on phonetic categorization. However, listeners who performed the discrimination task first showed no effect of lexical status. Since prior research has shown that the lexical effect is fairly robust [see Pitt and Samuel (1993)], the finding that the influence of lexical status can be eliminated by first placing listeners in an AXB discrimination task is the focus of the current research. The AXB task may focus attention on the prelexical, phonetic representation and differences within each phonetic category. This, in turn, eliminates the influence of higher level processes on phonetic perception in the identification task. The present study seeks to replicate this finding and investigate whether other lexical influences on perception (the influence of lexical neighborhood) are also altered by experience with AXB discrimination. Results are discussed in terms of the flow of information during phonetic perception and word recognition.
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