摘要:

A sonobuoy array placed in the nearshore lead was used for locating bowhead whale sounds to determine if whales migrated past census stations beyond visual range and were uncounted. Based on a sample of 182 whale sounds (over 48 h) from closest point of approach (CPA) distances out to more than 10 km, 68% originated beyond 2 km (CPA), where only 1% of the 242 whales were sighted. No whales were sighted beyond 3 km during this time, but 53% of the located sounds originated that far and beyond. Thirty‐seven other bowhead sounds over 15 h were distributed out to 6 km. Two tracked whales moved at average speeds of 1.5 and 1.8 kn. Maximum location error was 1%–25% in a sector of 120° × 5–10 km, depending upon bearing and range. Most whale sounds were low‐frequency moans, trumpeting roars, and repetitive sequences (songs) with peak spectrum source level up to 189 dBre: 1 μPa, 1 m. Lack of correlations between numbers of sounds and sighted whales precluded using bowhead sounds to count individuals or even to extrapolate ratios of unseen to observed whales.

ISSN:0001-4966    

DOI:10.1121/1.392933

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Adult canaries (Serinuscanarius) 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.

ISSN:0001-4966    

DOI:10.1121/1.392885

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

A procedure is described for synthesizing tone sequences that contain a high proportion of events that are likely to be found in melodies that occur in music. This is done by using a random‐number generator with probability weightings that favor the selection of certain notes and intervals. The form of the probability weightings derives from constraints on the ‘‘semitone span’’ of the intervals, the ‘‘fifth span’’ of the intervals, and the occurrence of ‘‘scale’’ notes. The role of ‘‘redundancy’’ is also considered. In this way it is possible to obtain melodies that obey various combinations of the different constraints. Other melody variables are either fixed, randomized, or controlled. These experimental melodies were used in a test of the hypothesis that the more melodious tone sequences will be easier to organize perceptually and remember than less melodious sequences of equal redundancy. A psychophysical scaling procedure confirmed that the constraints generated tone sequences bearing degrees of perceptual similarity to ‘‘real’’ melodies. Melody discrimination was also measured. The ‘‘fifth span’’ and ‘‘scale’’ constraints increased the melodiousness of tone sequences. They also improved performance on tasks requiring the discrimination of unfamiliar, untransposed melodies, and the discrimination of transposed melodies after some familiarization. It is argued that general perceptual principles do not give a complete account of the perception of melody: A full description requires consideration of the listener’s tacit musical ‘‘knowledge’’ and its interaction with perceptual processes.

ISSN:0001-4966    

DOI:10.1121/1.392886

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

The perceptual effects of orthogonal variations in two acoustic parameters which differentiate American English prevocalic /r/ and /l/ were examined. A spectral cue (frequency onset and transition ofF2 andF3) and a temporal cue (relative duration of initial steady state and transition ofF1) were varied in synthetic versions of ‘‘rock’’ and ‘‘lock.’’ Four temporal variations in each of ten stimuli of a spectral‐cue continuum were generated. Phonetic identification and oddity discrimination tasks with the four series showed systematic displacement of perceptual boundaries and discrimination peaks, thus reflecting a trading relation between the two cues. The perceptual equivalence of spectral and temporal cues was investigated by comparing the accuracy of discrimination of three types of stimulus comparisons: phonetically facilitating two‐cue pairs, one‐cue pairs, and phonetically conflicting two‐cue pairs. As predicted, discrimination accuracy was ordered: facilitating cues>one cue>conflicting cues, indicating that perceivers discriminated on the basis of an integrated phonetic perception.

ISSN:0001-4966    

DOI:10.1121/1.392887

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Consonant recognition in quiet using the Nonsense Syllable Test (NST) [Resnicketal., J. Acoust. Soc. Am. Suppl. 158, S114 (1975)] was investigated in 62 normal hearing subjects 20 to 65 years of age at their most comfortable listening levels (MCLs) and at 8 dB above and below MCL. Although overall consonant recognition performance was high (as expected for normal listeners), the effects of age decade, relative presentation level, and NST subsets were all significant, as was the interaction of age × level. The interactions of age × NST subset, and age × subset ×level were nonsignificant. These findings suggest that consonant recognition decreases with normal aging, particularly below MCL. However, the relative perceptual difficulty of the seven subtests is the same across age groups. Confusion matrices were similar across levels and age groups. Percent information transmitted for several consonant features was calculated from the confusion matrices. Older subjects showed decrements in performance primarily for the features recognized relatively less accurately by the younger subjects. The results suggest that normal hearing older individuals listening in quiet have decreased consonant recognition ability, but that their confusions are similar to those of younger persons.

ISSN:0001-4966    

DOI:10.1121/1.392888

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

The proportions of hits and false alarms were estimated for the detection of a 500‐Hz sinusoidal signal in each of 25, reproducible samples of wideband, white, Gaussian noise. The effects of signal phase were investigated under diotic (MoSo) and dichotic (MoSπ) conditions and compared to the predictions of two major models of binaural hearing. Averaging the data over samples obscured important across‐sample and across‐subject differences in performance. The proportions of hits and false alarms for individual noise samples presented under the MoSo condition were highly correlated with those for the same noise samples under the dichotic MoSπ condition, suggesting that the cues determining performance under these conditions are related. Signal‐to‐masker phase had a large effect on the proportion of hits under the MoSo condition, but only a small effect under the MoSπ condition. The Vector model predicts a large effect of signal phase under the MoSπ condition, and is, therefore, imcompatible with this aspect of the data. The expected value of the decision variable of the EC model is independent of signal phase. However, when the variance of the decision variable is also considered, the EC model does predict changes in the proportion of hits with the phase of the signal, comparable to those observed here. Further, it was shown that, if minor changes in the form of the EC model’s decision variable or in the distribution of the internal noise parameters are assumed, the expected value of the decision variable also changes with the phase of the signal.

ISSN:0001-4966    

DOI:10.1121/1.392889

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Simultaneous masking of a 20‐ms, 1‐kHz signal was investigated using 50‐ms gated and continuous sinusoidal maskers with frequencies below, at, and above 1 kHz. Gated maskers can produce considerably (5–20 dB) more masking than continuous maskers, and this difference does not appear to result from the spread of energy produced by gating either the masker or the signal. For masker frequencies below the signal frequency, this difference in masking is primarily due to the detection of the cubic difference tone in the continuous condition. For masker frequencies at and above the signal frequency, the difference appears to be an important property of masking. Implications of this frequency‐dependent effect for measures of frequency selectivity are discussed.

ISSN:0001-4966    

DOI:10.1121/1.392890

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Threshold for a 20‐ms, 1‐kHz signal was measured as a function of its temporal position within a longer duration gated masker; masker frequencies were below, at, and above 1 kHz. For a masker frequency above the signal frequency, there is a sizable temporal effect: As the onset of the signal is delayed, threshold decreases rapidly but then increases again as the signal approaches masker offset. Similar results can be observed for a masker frequency below the signal frequency, but that temporal effect is due to the detection of the cubic difference tone. The implication of this frequency‐dependent temporal effect for measuring psychophysical tuning curves is discussed.

ISSN:0001-4966    

DOI:10.1121/1.392891

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Reflex modification was used in a psychophysical technique to measure absolute auditory sensitivity of two species of anurans. Behavioral audiograms for these animals reveal that the bullfrog can detect sounds from 100 Hz to 3.2 kHz and the green tree frog from 100 Hz to 5 kHz. The shape and the sensitivity of these behavioral audiograms are similar to those of neural evoked‐response audiograms of these animals. Absolute auditory sensitivity of anurans is only partially related to the spectral composition of their species‐specific vocalizations.

ISSN:0001-4966    

DOI:10.1121/1.392892

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

The cancellation level and phase were measured for the (f2−f1) distortion product in six normal‐hearing ears as a function of input level (L1,L2) and the frequency separation of the two input signals (f1,f2, wheref2>f1). The effects of input level were examined forL1andL2, varied together (L1=L2) and separately. Typically,f1was 1500 Hz whilef2/f1was either 1.16, 1.32, 1.44, or 1.68. ForL1=L2, the median data indicate that the (f2−f1) level grows at a rate of approximately 1.1 dB/dB when averaged across all stimulus conditions. This slope tended to be higher (∼1.6 dB/dB) forL1=L2>80 dB. Slopes for some subjects also increase asf2/f1increases. The cancellation phase increases slightly (50°–100°) with an increase inL1=L2. WithL1at 75 to 80 dB,L2ranging from 65 to 95 dB, andf2/f1=1.16, (f2−f1) increases monotonically withL2up toL1=L2. AsL2increases further (L2>L1), the slopes for the growth of (f2−f1) decrease. Forf2/f1=1.44, on the other hand, (f2−f1) appears to grow monotonically at a rate of approximately 0.5 dB/dB throughout the range ofL2values. The cancellation phase increases withL2(approximately 100°) only for the wider frequency separation of the two input signals (f2/f1=1.44). There are, however, sizable individual differences in the behavior of the (f2−f1) distortion product.

ISSN:0001-4966    

DOI:10.1121/1.392893

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP