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R J Dooling

Publications and source records attributed to R J Dooling.

At least 55 records · Page 3Linked to original sources
PubMed1990

Speech perception by budgerigars (Melopsittacus undulatus): spoken vowels.

Discrimination of natural, sustained vowels was studied in 5 budgerigars. The birds were trained using operant conditioning procedures on a same-different task, which was structured so that response latencies would provide a measure of stimulus similarity. These response latencies were used to construct similarity matrices, which were then analyzed by multidimensional scaling (MDS) procedures. MDS produced spatial maps of these speech sounds where perceptual similarity was represented by spatial proximity. The results of the three experiments suggest that budgerigars perceive natural, spoken vowels according to phonetic categories, find the acoustic differences among different talkers less salient than the acoustic differences among vowel categories, and use formant frequencies in making these complex discriminations.

Animals↗
PubMed1989

Speech perception by budgerigars (Melopsittacus undulatus): the voiced-voiceless distinction.

Discrimination of synthetic speech sounds from the bilabial, alveolar, and velar voice onset time (VOT) series was studied in 5 budgerigars. The birds were trained, using operant conditioning procedures, to detect changes in a repeating background of sound consisting of a synthetic speech token. Response latencies for detection were measured and were used to construct similarity matrices. Multidimensional scaling procedures were then used to produce spatial maps of these speech sounds, in which perceptual similarity was represented by spatial proximity. The results of these experiments suggest that budgerigars discriminate among synthetic speech sounds from these three VOT continua, especially between those from the bilabial and alveolar series, in a categorical fashion.

Animals↗
PubMed1988

Obtaining acoustic similarity measures from animals: a method for species comparisons.

An efficient procedure has been developed for obtaining similarity measures for complex acoustic signals in small birds. Birds were trained using operant conditioning procedures to detect changes in the repeating background of an ongoing sound. Response latencies for detection were used to construct similarity matrices. Multidimensional scaling procedures were then used to produce spatial maps of these complex sounds reflecting perceptual organization. An example using contact calls from two avian species is described.

Animals↗
PubMed1987

Auditory pathways in the budgerigar. I. Thalamo-telencephalic projections.

Thalamo-telencephalic auditory pathways in the budgerigar (Melopsittacus undulatus) were studied using horseradish peroxidase (HRP) histochemistry and amino acids autoradiography. The results indicate that in this species the thalamic auditory relay nucleus, n. ovoidalis, projects upon a circumscribed region of the caudal and caudomedial neostriatum including field 'L' and immediately adjacent portions of the neostriatum intermedium, pars dorsolateralis (NIDL). This region of NIDL also receives inputs from another thalamic nucleus, n. dorsolateralis posterior (DLP). In the DLP is in receipt of tectal inputs. Projections of DLP upon NIDL were confirmed with amino acids autoradiography. The results of the HRP experiments indicate that different portions of n. ovoidalis project upon different portions of field 'L' and NIDL. Neurons in the dorsal and lateral portions of the n. ovoidalis project upon more medial portions of field 'L'. Neurons located centrally in the n. ovoidalis project upon central and lateral portions of field 'L'. Neurons in the ventromedial portion of the n. ovoidalis are labeled in all cases in which HRP is placed in either field 'L' or in the DLP projection field immediately adjacent to field 'L' proper. HRP injections placed in NIDL lateral to the projection fields of the n. ovoidalis and DLP label neurons within other diencephalic nuclei including the n. subrotundus. The caudal and intermediate levels of the neostriatum intermedium apparently serve as a complex processing area for many thalamic inputs in this species. The existence of multiple ascending thalamo-telencephalic projections from portions of the thalamus receiving inputs from both the visual (i.e., tectal) and auditory (i.e., n. mesencephalicus lateralis pars dorsalis) portions of the midbrain roof (i.e., from DLP and from n. ovoidalis) suggests the possibility that intermodal associations may take place in these telencephalic fields. Such partially converging pathways may provide a basics for intermodal associations which are important in individual recognition and social signalling systems in this species.

Animals↗
PubMed1987

Hearing in passerine and psittacine birds: a comparative study of absolute and masked auditory thresholds.

Operant conditioning and a psychophysical tracking procedure were used to measure auditory thresholds for pure tones in quiet and in noise for seven species of small birds--the budgerigar, canary, cockatiel, European starling, song sparrow, swamp sparrow, and the zebra finch. Audibility curves are roughly similar among the seven birds, with the maximum sensitivity between 2 and 5 kHz and poorer sensitivity outside this narrow region. Critical ratios (signal-to-noise ratio at masked threshold) were calculated from pure-tone thresholds in noise. Except for the budgerigar, the critical ratio functions of all birds increase at the rate of 3 dB/octave. This pattern is typical of that observed in most vertebrates. Critical ratios in the budgerigar, on the other hand, decrease gradually from 0.5 kHz to 2.8 kHz and increase dramatically above 2.8 kHz. The present research demonstrates that the critical ratio function for the budgerigar is not only different from other vertebrates but also different from other birds.

Animals↗
PubMed1987

Strain differences in auditory thresholds in the canary (Serinus canarius).

Canaries (Serinus canarius) of the Belgian waterslager strain from two different colonies were trained with operant techniques for audiometric testing. For both young and old birds, absolute thresholds in the middle- to high-frequency region of the audiogram were between 30 and 40 dB (SPL) higher than those of other song birds, including canaries of other strains. Thus the Belgian waterslager canary, selectively bred for loud, low-pitched song, has also developed poor high-frequency hearing.

Aging↗
PubMed1986

Perception of vocal signals by budgerigars (Melopsittacus undulatus).

Budgerigars were trained with operant techniques to discriminate examples of species-specific contact calls. Results show that these birds are capable of learning and remembering for long periods of time both species-specific vocalizations and other complex acoustic signals. While both temporal and spectral cues are important in the discrimination of species-specific calls by the budgerigar, spectral cues occurring in the region of 2 to 4 kHz appear to be critical. These findings are consistent with what is known about spectral resolving power in the budgerigar from critical band, critical ratio, and psychophysical tuning curve experiments. Differences between budgerigars and humans in the filtering properties of the peripheral auditory system may account for species differences in the perception of complex bird calls. In further tests for perceptual categories, multidimensional scaling procedures confirm that contact calls sound different to budgerigars than they do to humans. In addition to providing more evidence for special tuning in the spectral region of 2-4 kHz, these experiments also support the notion of a generalized, flexible, and highly sophisticated perceptual learning system in the budgerigar for the processing of vocal signals.

Animals↗
PubMed1985

Temporal integration of acoustic signals by the budgerigar (Melopsittacus undulatus).

Avoidance conditioning and a modified method of limits psychophysical procedure were used to study temporal integration of tone and noise signals in the budgerigar (Melopsittacus undulatus). Integration of both tone and noise signals can be described by a negative exponential function with a time constant of about 200 ms. At very short durations there were differences in the integration of tone and noise signals. These data are similar to those reported for a number of other vertebrates, including man. Thresholds for two complex natural vocalizations of the budgerigar are similar to those of pure tones of equivalent duration.

Animals↗
PubMed1985

Colony differences in auditory thresholds in the canary (Serinus canarius).

Adult canaries (Serinus canarius) from a closebred colony of the Belgian "Waterslager" strain were trained with operant techniques to respond to pure tones. A psychophysical tracking procedure was used to measure absolute auditory thresholds in quiet and in noise. Absolute thresholds in the middle- to high-frequency region of the audiogram were between 30 and 40 dB higher (4-5 standard deviations) than those typically reported for other song birds including canaries of other strains and Waterslagers tested some years ago from another colony. Thus the Millbrook colony of domestic canary--an oscine songbird which learns its vocalizations by reference to auditory information--shows unusually high absolute thresholds for pure tones.

Animals↗
PubMed1985

Nonsimultaneous auditory masking in the budgerigar (Melopsittacus undulatus).

The frequency resolving power of budgerigars and that of humans were compared on several nonsimultaneous masking procedures in which one pure tone is used to mask another. Similar patterns of frequency selectivity were found for all three masking procedures (forward, backward, and combined forward-backward) for both species. Budgerigars showed considerably greater frequency resolving power on all three procedures than humans. Budgerigars also showed differences in frequency resolving power across masking conditions, but human listeners did not. These results indicate that the budgerigar auditory system may be even more highly tuned than was previously thought and suggest fundamental differences between the mechanisms of frequency selectivity of bird and those of humans.

Animals↗
PubMed1985

Perception of species-specific contact calls by budgerigars (Melopsittacus undulatus).

Three budgerigars were trained with operant techniques to discriminate examples of species-specific contact calls. Budgerigars were also tested on vocalizations from another avian species--the canary (Serinus canarius). Budgerigars showed an equivalent ability to discriminate and remember both budgerigar and canary calls. Additional tests showed that both temporal and spectral cues were important in the discrimination of species-specific calls by the budgerigar. However, spectral cues occurring in the region of 2.0-4.0 kHz appear to be critical for the discrimination. These experiments support the notion of a generalized, but highly sophisticated, perceptual learning system in the budgerigar for the processing of vocal signals.

Animals↗
PubMed1980

Forward and backward auditory masking in the parakeet (Melopsittacus undulatus).

Backward, foward and simultaneous masking of brief tone pulses was examined in four parakeets. The pattern of non-simultaneous masking in parakeets is quite similar to that observed in humans with rates of threshold recovery faster for backward compared to forward masking conditions. These results may have relevance for the design of vocal signals and the coding of species-specific information in parakeets.

Animals↗
PubMed1979

Temporal summation of pure tones in birds.

Two parakeets and two field sparrows were trained by a method of avoidance conditioning to respond to pure tones. Absolute thresholds were obtained for 10 durations of a 2.86-kHz tone. The temporal integration function for these four birds can best be described by a time constant pi of 230 ms. These data are similar to those reported for a number of other species.

Animals↗
PubMed1978

Auditory sensitivity, equal loudness, temporal resolving power, and vocalizations in the house finch (Carpodacus mexicanus).

Absolute thresholds for pure tones were measured in four house finches by use of avoidance conditioning and a modified method of limits. Response reaction time to each tone presentation served as a data base for generating a family of "equal loudness" contours. Temporal resolving power was measured in two additional birds and compared with similar measures in man. The results are discussed in relation to previous studies of vocalizations in the house finch, and the average power spectra of selected individual vocalizations are presented.

Animals↗
PubMed1978

Auditory duration discrimination in the parakeet (Melopsittacus undulatus).

Two parakeets were trained by a method of avoidance conditioning to respond to duration differences in successively occurring tone bursts. Difference limens for duration were obtained at six durations (20-160 ms) of a 2.86-kHz tone presented at a sensation level of 60 dB. Calculations of the Weber fractions at each duration showed threshold values which compare favorably to similar measures for man ranging between 0.10 and 0.20.

Animals↗
PubMed1975

Hearing in the parakeet (Melopsittacus undulatus): absolute thresholds, critical ratios, frequency difference limens, and vocalizations.

Avoidance conditioning and the method of limits were used to measure absolute auditory thresholds, masked thresholds, and critical ratios in 4 parakeets. The same procedure was then used to study frequency difference limens in 6 additional animals. The power spectrum and "constancy of intonation" of the parakeet call were also measured and related to the absolute and differential frequency sensitivity. The mechanism of frequency analysis in the parakeet ear was considered in relation to the present results and to the anatomical and functional differences between the avian and mammalian auditory systems.

Acoustic Stimulation↗