摘要:

Upon introducing the outgoing spherical (or circular cylinder) partial waves {ψn} as a basis, the equationQT= − Re (Q) is obtained for the transition matrixTdescribing scattering for general incidence on a smooth object of arbitrary shape. Elements ofQinvolve integrals over the object surface, e.g.Qmn = ±(i2)δmn+(k8π)∫dσ⋅∇[Re(ψm)ψn]. where the −, + apply for Dirichlet and Neumann conditions, respectively. For quadric (separable) surfaces,Qis symmetric. Symmetry and unitarity lead to a secular equation defining eigenfunctions for general bodies. Some apparently new closed‐form results are obtained in the low frequency limit, and the transition matrix is computed numerically for the infinite strip.

ISSN:0001-4966    

DOI:10.1121/1.1911619

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A system for tracking difference limen for frequency (ΔF) is described. The system uses a function generator to frequency modulate a BFO. The amplitude of the modulating voltage is controlled by a recording attenuator. Intuitive spectral analysis of the modulated tone proves to be insufficient and correction factors are given to allow determination of ΔFfrom de calibration data. When real rather than intuitive spectrum is used for calibration of the system, ΔFdoes not increase with modulation rate from 1 to 16 Hz. Consideration of the spectra produced by various waveforms indicates that the discrepancy between de calibration and spectral width is minimal for a trapezoidal modulating waveform.

ISSN:0001-4966    

DOI:10.1121/1.1911620

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A signal was presented in each observation interval of two‐alternative, temporal‐forced‐choice trials, and 12 observers each selected the louder of the two signals. The observers were informed that the signals of each trial would be of 1000 Hz and either 2 or 4 dB different in amplitude. Some 70% of the trials did in fact present such pairs of 1000‐Hz signals. Surreptitiously, on infrequent and randomly determined trials, one of the signals presented, a probe signal, was of a frequency other than 1000 Hz. The probe‐signal method thus applied to the nominal amplitude discrimination task produced results clearly demonstrating differential performance as a function of the signal frequency, for 10 of the 12 observers. For those 10 observers, the relation between performance and signal frequency appears asymmetrical about 1000 Hz.

ISSN:0001-4966    

DOI:10.1121/1.1911621

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

In the guinea pig, the cochlear‐microphonic potentials and the summating potential (SP) have been simultaneously recorded by means of micropipettes located inside the scala media of each turn of the cochlea. The polarity of the SP recorded in the first turn is negative for the high frequencies (i.e., 6000 Hz) at low levels of sound pressure. For the lower frequencies (i.e., 900 Hz), the SP is recorded positive before it becomes negative. The lower the frequency, the greater the SPL (sound‐pressure level) required to produce a negative SP in the first turn. The SPL at which the SP for low frequencies becomes negative is lower the greater the distance from the oval window. The SP magnitude is linearly dependent upon the logarithm of the duration of sound within the range of values investigated from 40 msec to 2 sec. The amplitude of the negative SP rose monotonically as the intensity of the stimulus was increased, and the neighboring areas of the basilar membrane contributed to the production of the SP. Increase in duration of stimulation increased the amplitude of the SP without bringing into activity new areas of basilar membrane.

ISSN:0001-4966    

DOI:10.1121/1.1911622

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Extensive psychological experiments were carried out in this Part I on the consonance sensation of various dyad tones consisting of two components. As the frequencies of two componentsf1andf2(with an equal SPL) separate, the consonance gradually decreases down to the most dissonant point, whereafter it monotonically increases and mostly recovers at an octave separation. This consonance characteristic turned out to show a simpleVcurve if consonance is plotted against the frequency percent deviation in a logarithmic scale, and it suggests a dynamic and a static factor in consonance perception. The most dissonant frequency deviation is approximately 10% atf1=440 Hz, and it increased with sound pressure and frequency, but it was not simply proportional to the critical bandwidth. For dyads whose two components have different sound‐pressure levels (SPLs)L1andL2, the consonance differs with spectrum forms, even when the level difference is the same. A dyad with a spectrum form (P1>P2,f1

ISSN:0001-4966    

DOI:10.1121/1.1911623

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A theory for calculating subjective dissonance of static complex tones has been established. The theory proposes a dissonance perception model that assumes that the mutual interactions between two components constitute an essential additive unit contributing to the dissonance. The model introduces a new concept of “dissonance intensity” in a certain process of dissonance perception and extends the “power law” to the dissonance sensation, which is not clearly related to a certain physical value. Practical calculation procedures are described according to the experimental results of dyads in Part I. Theoretical calculation for various kinds of complex tones showed good agreements with psychological experiments. An application to chords of synthesized harmonic complex tones predicted great dependence of consonance characteristics on the harmonic structures, which are not taken into account in the conventional theory of harmony. It became clear that the fifth (2:3) is not always a consonant interval. A chord of two tones that consists of only odd harmonics, for example, shows much worse consonance at the fifth (2:3) than at the major sixth (3:5) or some other frequency ratios. This was proved true by psychological experiments carried out in an other institute (Sensory Inspection Committee in the Japan Union of Scientists and Engineers) with a different method of scaling. Thus, the fact warns against making a mistake in appling the conventional theory of harmony to synthetic musical tones that can take variety in the harmonic structure. The theory next explains difference in quality reduction of reproduced sounds through a nonlinear audio instrument by the physical characteristics of input sources, and it provides a measure of evaluating nonlinear distortion.

ISSN:0001-4966    

DOI:10.1121/1.1911624

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Twelve experienced subjects participated in a Békésy‐type tracking procedure and obtained their thresholds for a 25‐ and a 300‐msec duration 1‐kHz pulsing auditory stimulus in the absence and presence of time‐locked stroboscopic visual stimulation. Six subjects obtained their thresholds in quiet, and the remainder tracked threshold in the presence of white noise. The data indicated that psychophysical sensory interaction between the auditory and visual systems does not occur when auditory thresholds are assessed in the presence of visual stimulation. Auditory thresholds were neither facilitated nor inhibited. These generalizations applied whether thresholds were obtained for short‐ or long‐duration auditory stimuli in quiet or in the presence of a masking stimulus. Similar results were obtained for attenuator pen excursion size. A hypothesis is presented suggesting that the potential for psychophysical sensory interaction to occur between the visual and auditory modalities may increase as the magnitudes of sensory stimuli presented to them increase.

ISSN:0001-4966    

DOI:10.1121/1.1911625

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Receiver operating characteristic (ROC) curves and psychometric functions for detection of 1000‐Hz sinusoids presented against a background of narrow‐band noise were obtained using a one‐interval rating‐scale procedure. Signals were added to noise alone (simpledetection) or to noise plus sinusoidal pedestal (pedestaldetection). While almost all stimulus‐oriented theories of signal detectability predict a monotonically decreasing relation for the slope of the ROC curve as a function of signal strength, slopes of the empirically determined ROC's never showed a systematic decrease with increases in signal amplitude. Significant differences between the range of the psychometric functions for simple‐ and pedestal‐detection conditions were noted. Two modifications of the basic signal‐detection approach, a fluctuating criterion model and a neural counting scheme, are proposed to account for the data. An investigation of the neural counting model was carried out in computer simulation, and the influence of various exponents in the power‐law transducer function relating stimulus energy and neural counts was examined. Implications of the theoretical and empirical results for our notions about the nature of the underlying probability distributions and decision mechanisms are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911626

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The effects of temporal and lateral uncertainty were separately shown to produce decrements in the detectability of a tonal signal in noise. Rating procedures were used, together with left/right recognition responses where appropriate. When both dimensions of uncertainty were present simultaneously, the interaction was found to be complex. Observed false‐alarm rates provided a reliable index of the possible detection strategies involved in these tasks.

ISSN:0001-4966    

DOI:10.1121/1.1911627

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The pitch elicited by 300‐, 1000‐, and 3000‐Hz sinusoids frequency modulated by 20, 200‐, and 2000‐Hz sinusoids (the latter for the 3000‐Hz carrier frequency only) was investigated at 20 and 50 dB SL. The frequency deviation of the carrier frequency was ± 100 Hz for all stimulus conditions. Five normal‐hearing listeners matched unmodulated sinusoids in a free‐response task to any and all “pitches” perceived in the FM signals. Pitch matches occurred to individual spectral components when the component frequency spacing exceeded critical bandwidth. When component spacing was less than critical bandwidth, pitch matches occurred randomly within the energy band, at the center of the energy band, or at the ends of the energy band. No pitch matches were made in response to anything but spectral‐energy information.

ISSN:0001-4966    

DOI:10.1121/1.1911628

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP