摘要:

A previously proposed upper bound on the performance of psychophysical techniques that attempt to determine points on psychometric functions is shown to be a least upper bound. The existence of a realizable technique (the Robbins‐Monro process) which asymptotically attains the performance of the proposed ideal shows that this ideal provides an appropriate basis from which to calculate the absolute as opposed to relative efficiency of real psychophysical measurement techniques. The concept of incremental efficiency is introduced. It is shown to be useful in analyzing the performance of measurement techniques when the initial uncertainty of the estimate, often ignored in simulation studies, is neither infinite nor zero, and to permit independent assessment of the efficiency of separate portions of a measurement process.

ISSN:0001-4966    

DOI:10.1121/1.1912379

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Various possible mechanisms for the generation of harmonics in the tone of the trumpet were investigated. By sounding the trumpet with a mechanical valve utilizing a sinusoidally varying opening, it was shown that nonsinusoidal motion of the player's lips is not an important mechanism for harmonic generation. Nonlinear behavior of the air column of the instrument due to high sound pressures was also shown not to be important by four different methods: (1) by a theoretical estimate of the amount of second‐harmonic distortion to be expected; (2) by measuring the input resistance of the trumpet at resonance frequencies and finding that it did not vary significantly with sound pressure in the air column; (3) by measuring the intermodulation distortion produced when the air column was excited at two resonance frequencies simultaneously; and (4) by direct measurement of harmonic distortion produced in the trumpet output by different levels of excitation at the mouthpiece. It was found that the mechanism primarily responsible for harmonic generation is the relationship between the input impedance of the trumpet and the time‐varying impedance of the player's lip opening during a cycle. Curves of mouthpiece pressure calculated on this basis showed good agreement with observed waveforms.

ISSN:0001-4966    

DOI:10.1121/1.1912380

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Three keyless flutes of identical internal dimensions were made of thin silver, heavy copper, and wood, respectively. They were played out of sight of musically experienced observers, who were asked to determine only whether tones were alike or different. No statistically significant correlation between the listeners' scores and the material of the instrument body was found. Flutists who played the flutes, using an arrangement to eliminate visual or tactile clues, were unable to identify again a previously selected instrument.

ISSN:0001-4966    

DOI:10.1121/1.1912381

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Melodic contour (the sequence of ups and downs in a melody, regardless of interval size) expresses those aspects of a melody that are most essential to manipulation of that melody in various musical structures, e.g., folktunes and fugues. This is demonstrated by brief analyses of actual music. Two experiments demonstrate the role of melodic contour recognition in memory for melodies. Experiment 1 (2×3 factorial design) involved short‐term memory with comparison melodies either transposed or not transposed from the key of the standard. Separate groups had the tasks of distinguishing (a) between same and different melodies; (b) between same melodies and ones with only the same contour; and (c) between melodies with the same contour and different ones. The effects of transposition and task and their interaction were significant (p<0.001). Untransposed melodies were recognized by their exact pitches, so that tasks (a) and (b) were equally easy. Contour recognition was more important with transposed melodies, so that task (b) was very difficult, and tasks (a) and (c) were easier. Task (c) was about equally difficult under both conditions. Experiment 2 involved recognition of distorted versions of familiar folktunes having the same length and rhythmic structure. In ascending order of recognizability, these distortions preserved merely the harmonic basis of the melody, the melodic contour, and the contour plus the relative sizes of successive intervals between notes (chi‐square = 50.4,p<0.001).

ISSN:0001-4966    

DOI:10.1121/1.1912382

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The velocity of a bowed violin string was measured at various points along its length and with various bow positions by placing a magnetic field perpendicular to the string and observing the voltage induced in the string. The string was found to oscillate in a simple triangular pattern described by Helmholtz. At all points on the string, the ratio of flyback time to period of the oscillation equaled the distance from bridge to observation point divided by string length. This equality implies that larger‐amplitude vibrations for a given bow speed can be achieved by bowing closer to the bridge. It also implies that the waveform at the bridge has an exceedingly rapid flyback time and hence is rich in high‐frequency components which are transmitted to the body of the instrument. Deviations from a triangular waveform were observed. These consist of slight rounding of the corners of the triangle and a superimposed sinusoidal oscillation of small amplitude.

ISSN:0001-4966    

DOI:10.1121/1.1912383

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

CVC and CVVC syllables were prepared in which the final consonants were either nasal consonants (/m/, /n/) or non‐nasal consonants. The entire final consonant along with its vowel‐consonant transition was spliced away. The resulting CV and CVV syllables along with carrier phrases were spliced at random onto a tape for presentation to listeners who were asked to predict whether the missing consonant was nasal or nonnasal. Results indicate that the presence of nasal consonants can be predicted very well. It is hypothesized that listeners utilize this information to lighten the phoneme‐processing load. Such perceptually significant coarticulation of velar opening across the vowels in CVVN‐type sequences probably has counterparts in the coarticulation of other articulatory gestures. In this way, perception uses or follows production.

ISSN:0001-4966    

DOI:10.1121/1.1912384

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The vocal tract was excited transcutaneously at a point just above the glottis by an external sweep‐tone signal, in order to measure its transfer characteristics acoustically as continuous frequency functions. An analysis‐by‐synthesis procedure derived reliable data of vowels, in particular of the formant bandwidths, for three male and three female normal subjects. It has been shown for the closed glottis condition that the first formant bandwidths are higher for close vowels (typically 70 Hz for male subjects) than for semi‐open vowels (typically 35 Hz for male subjects). Stationary consonantal articulations including stops, nasals, and nasalized vowels also have been studied, as well as the effect of opening the glottis on the vocal‐tract transfer characteristics. The stop articulations give rise to a first‐formant frequency slightly below 200 Hz. This fact and the high dissipation of the first formant is explained by assuming nonrigidness of the surrounding wall. Characteristics of nasalized vowels and nasal murmurs are also discussed based on the data obtained in this experiment.

ISSN:0001-4966    

DOI:10.1121/1.1912385

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The relationship between the development of a phonological system and auditory perception was studied by examining children's errors in discriminating among a group of English consonants. The perceptual equivalence and additivity of linguistic features were studied. A nonmetric multidimensional analysis procedure was used in an attempt to specify the number of processes by which children made decisions, and speculations about the nature of these processes were made. The discrimination errors of the children were similar to those of adults, except that the children produced more errors. The results failed to show that current linguistic descriptions identify the perceptual parameters children use in categorizing speech sounds.

ISSN:0001-4966    

DOI:10.1121/1.1912386

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The structure of perceptual confusions among 10 Hindi vowels /i, I, e, ɛ, a, ʌ, ɔ, o, U, u/ was studied in clipped speech. Front vowels were recognized better than back vowels. It has been found in most of the cases that the first and the second probable incorrect vowels have either openness of the vocal tract or place of articulation in common with the corresponding correct vowel. This finding supports the view that vowels can be perceived by these two distinctive features only. The same two distinctive features (dimensions) have been used by Wickelgren [J. Acoust. Soc. Amer.38, 583–588 (1965)] to explain the coding of vowels in short‐term memory.

ISSN:0001-4966    

DOI:10.1121/1.1912387

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Many factors contribute to the variability of an ensemble of measured fundamental frequency (Fo) contours. These include, among others, differences between speakers, differences between replications of the utterance by the same speaker, and errors of estimation. Unfortunately, the relative contribution of the different sources of variability vary during the course of an utterance. We discuss in detail a method for analyzing such data by subdividing the time axis into a series of time windows and approximating the Fo contour within each window by a set of orthogonal polynomials. An analysis of variance is then carried out on the coefficients of each polynomial expression. Consistent trends in coefficient values between contiguous time windows are then approximated by sets of orthogonal polynomials. The technique is not only a powerful method for evaluating quantitatively the effects of different sources of variability, including changes in the degree of variability during an utterance, but also provides a basis for comparing directly the effect of short‐term smoothing of contours with that of approximating long‐term trends. Both these effects may also be compared directly with those of averaging over replications or averaging over both subjects and replications. These effects can be rank ordered in terms of a least‐squares criterion, thereby isolating those factors which have the greatest influence on contour shape. The technique can also be used to separate out within‐subject and between‐subject differences in contour shape. An analysis of two utterances repeated three times by each of three subjects showed that inter‐replication differences were relatively small and that a good fit to the measured fundamental frequency contours (rms deviation ≈2 Hz) could be obtained by using an average contour for each subject. A single mean contour could be fitted to the entire utterance, but in this case the rms deviation was close to 4 Hz. There were also substantial differences in variability during the course of the utterance, the stressed portions being less variable than the nonstressed portions.

ISSN:0001-4966    

DOI:10.1121/1.1912388

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP