摘要:

Interference with thresholds for spondees and intelligibility of monosyllabic words (at 60 dB SPL) produced by combining modulated white noise (4 mod/sec, − 10 dB interburst ratio) and connected speech as simultaneous maskers was studied under a variety of interaural listening conditions at each of three masker levels (66, 72, and 78 dB sound‐pressure level). Monaural performance in the presence of both maskers (CmNmSm) was 7.8–10.5 dB poorer than with either masker alone (NmSmor CmSm). Thus, the two maskers produced added interference substantially in excess of the approximately 3‐dB increase to be expected on the basis of the summing of their powers alone. Very little release from masking was achieved in the transition from monaural (CmNmSm) to homophasic listening (C0N0S0). During antiphasic (CτNπS0) presentation, approximately 5 dB of release from masking occurred (reC0N0S0). A little less than half as much release from masking appeared when the maskers were given 0.8 msec interaural time delays, while the test material remained in phase at the two ears. Performance with opposing interaural delays (C0.8N0.8S0) was no better than with parallel time delays (C0.8N0.8S0). Since neither of these conditions yielded as large masking‐level difference as did the antiphasic, even though the sources of signals were lateralized (localized) much more sharply by the subject during time‐delay conditions, this study offers further evidence that localization (separation of source azimuths) and the capacity to understand speech against competing sounds are separate capacities. Various implications of the finding are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1910971

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

A previously unrecognized anomaly of pitch perception was discovered by H. F. Stimson while testing his hearing. Signals above 3500 Hz did not produce the same pitch in each ear; the right ear's sensation was that of a sound at a lower frequency, for which he also had normal pitch perception. Between 3700 and 5200 Hz, the pitch perceived in the right ear was independent of the frequency of the stimulus. As intensity was raised, additional pitches appeared; and for an intense sound, a chord was heard whose constituents were not harmonically related. Stimson can match these anomalous pitches with sinusoidal stimuli of the appropriate lower frequency within about 2%; part of this variation is a change of pitch with intensity. Tones in his normal pitch range having a pronounced overtone structure are perceived as multiple. Overtones falling in the anomalous range give rise to the anomalous pitch. This would indicate a Fourier type of analysis before pitch recognition. Beats are not excited by interference between the pitches evoked by signals in the anomalous range and those heard normally. Loudness studies show signal powers to be additive. Tone‐masking and loudness summation experiments yield data suggesting that the pitch recognition mechanism lies in that part of the auditory system in which loudness is perceived—i.e., beyond the cochlea.

ISSN:0001-4966    

DOI:10.1121/1.1910972

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

Monaural bone‐conduction thresholds at the mastoid process and frontal bone were obtained on several groups of young adults with normal hearing. The results are reported in force thresholds (decibelsre1.0 dyn rms) from calibrations made on a Beltone artificial mastoid. The data at the mastoid are in close agreement with the HAIC interim norm and the results of Westonet al.(1967). These results confirm the clinical usefulness of the HAIC interim norm. Likewise, the similarity between the current data obtained at the frontal bone and that reported by Westonet al.(1967) provides a basis for an interim norm until the International Organization for Standardization has completed its deliberations.

ISSN:0001-4966    

DOI:10.1121/1.1910973

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

When two or more sound sources radiate identical or nearly identical complex signals, the listener hears a single image located at the nearer source, provided that the delay involved is between about 1 and 50 msec. This phenomenon (together with other closely associated aspects) is generally referred to as the “precedence effect” or “Haas effect.” Less frequently, the terms “law of the first wavefront,” “auditory‐suppression effect,” “first‐arrival effect,” and “threshold of extinction” have also been used in describing certain of these characteristics. Perhaps the earliest investigator to leave a clear record of his appreciation of the single‐image aspect of the phenomenon was Joseph Henry who, in 1849, used the termlimit of perceptibilityin describing what he had observed. The present paper outlines the historical background of the effect from the standpoint of its investigation and its application in electroacoustical systems.

ISSN:0001-4966    

DOI:10.1121/1.1910974

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

The just noticeable difference in phase (ΔΘ) was measured for binaural stimulation and for stimulation of the ring and index fingertips of the same hand. At stimulus frequencies of 40, 60, 120, and 240 Hz, differences in phase up to 120° had no effect on cutaneous localization, while the values of binaural ΔΘ were only 3.6° and 3.3° for 120‐ and 240‐Hz tones, respectively. When the vibration frequency was lowered to 20 Hz, a cutaneous ΔΘ of 47° was obtained. At this frequency, the locus of cutaneous stimulation was found to greatly influence ΔΘ. When the index fingertips of the two hands were stimulated, ΔΘ was 90°, and was 45° when the ring and index fingertips of the same hand were stimulated. A relatively low ΔΘ of 12° was obtained when both vibrator contactors were placed on the same fingertip. The results of this study fail to support von Békésy's hypothesis that the same time delays in stimulation are equally effective as cues in auditory localization and its cutaneous analog.

ISSN:0001-4966    

DOI:10.1121/1.1910975

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

The ability of listeners to locate sound in the vertical plane was investigated. The results showed that for auditory stimuli to be located accurately (1) the stimulus must be complex, (2) it must include frequencies above 7000 cps, and, (3) the pinna must be present.

ISSN:0001-4966    

DOI:10.1121/1.1910976

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

Listeners, when requested to judge the location of tone bursts on the vertical plane, tended to place the stimuli on a vertical scale in accordance with their respective pitch. Higher‐pitched sounds were perceived as originating above lower‐pitched sounds. This phenomenon was also observed in congenitally blind persons and in young children who presumably were unaware of the use of the wordshighandlowin describing differently pitched sounds. In additional tests, visual cues were found to influence the range of the scale within which listeners perceived the sound sources and they could even bias the location judgments of high‐pitched tone bursts despite contrary binaural cues. But the main implication of the data is that tonal stimuli have intrinsic spatial characteristics, which result in the perception of frequencies with shorter periods as being higher in space than those with longer periods.

ISSN:0001-4966    

DOI:10.1121/1.1910977

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

Contralateral threshold shift has been investigated as a function of frequency difference between the masking and test tones. The obtained curves of frequency distribution indicate complex underlying processes. Both the masker intensity and the time delay from the masker onset affect the absolute amount as well as the frequency distribution of central masking. The frequency spread of masking appears consistent with the critical‐band measures at medium masker levels but not at high and low levels.

ISSN:0001-4966    

DOI:10.1121/1.1910978

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

Equipment has been constructed that will automatically plot on a chart the resonance curve for a clarinet as produced by external excitation with sound of constant pressure amplitude. On the same chart are plotted for comparison the frequencies of the harmonics of the lowest resonance. The harmonic structure of the sound pressure in the mouthpiece of the instrument when sounded by blowing with an artificial embouchure is also plotted for further comparison. It is found for the lowest notes on the clarinets used that the resonances lie at frequencies progressively lower than the harmonic frequencies. Even harmonics are present in the standing wave in the instrument when sounded, although the odd ones predominate out to the fifth harmonic; only the second is completely absent. As the scale is ascended, the resonances get more out of tune with the harmonics and decrease in number until for the (written) note B♭4, before the change to the next register, there are only two strong resonances. In the next register, the resonances appear to bear only a fortuitous relationship to the harmonics, and the second harmonic is present. Comparison of resonance curves for instruments of different manufacture shows them to be remarkably similar.

ISSN:0001-4966    

DOI:10.1121/1.1910979

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

A language maybe synthesized by combining, in a suitable way, elementary speech segments that have been extracted from the utterances of a native speaker of that language. The main criteria for the choice of these elements are discussed. The discussion leads to the definition of a new set of physically determinate linguistic elements that can be obtained by experiment. A preliminary list is reported for the Italian language. From experimental tests, it appears that it is possible to synthesize Italian speech with a small number of elements. These elements may form the basis for research in speech recognition.

ISSN:0001-4966    

DOI:10.1121/1.1910980

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP