摘要:

Flat‐spectrum stimuli, consisting of many equal‐amplitude harmonics, produce timbre sensations that can depend strongly on the phase angles of the individual harmonics. For fundamental frequencies in the human pitch range, many realizable timbres have vowel‐like perceptual qualities. This observation suggests the possibility of constructing intelligible voiced speech signals that have flat‐amplitude spectra. This paper describes a successful experiment of creating several different diphthongs by judicious choice of the phase angles of a flat‐spectrum waveform. A possible explanation of the observed vowel timbres lies in the dependence of theshort‐timeamplitude spectra on phase changes.

ISSN:0001-4966    

DOI:10.1121/1.393292

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

In this investigation, measurements of windchest pressure, organ pipe sound output, and air velocity into the foot of a small pipe are displayed as functions of time, using a long windchest note channel with a hand‐operated pallet valve. For rapid opening of the pallet, the pressure signal advancing along the channel consists of (a) a negative pulse due to the pallet displacement, followed by (b) a rising pressure step of heightp, typically 80% to 95% of the supply pressure. When the pressure step is reflected from the rigid far end of the channel, a pressure pedestal of height 2pand duration equal to the double passage time is observed there. With further reflections, the pressure changes continue as damped oscillations which depend in detail upon position in the channel. These results indicate that a long channel must be considered as an acoustic transmission line. An extension tube was also added to the end of the note channel. The pressure attained at the end of the extension tube was nearly 3p(theoretical limit 4p) as a result of reflection from its end in addition to the reflection at the impedance discontinuity between the tube and the note channel.

ISSN:0001-4966    

DOI:10.1121/1.393293

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

In the literature there are several references which imply that various parts of a hearing aid are sources of constant volume velocity. Reported herein are the findings of an investigation of the validity of such statements. A computer scheme, referenced elsewhere, for modelinginsituhearing aids was utilized to test the constant‐volume‐velocity hypothesis. In particular, capabilities of the receiver, ear hook, and earmold tip to deliver constant volume velocity were investigated via a computer. To facilitate such an investigation, a universal receiver/earmold model was created. This model was broken down into ‘‘source’’ and ‘‘load’’ at three locations: the receiver output, output of the ear hook, and medial tip of the earmold. At each location comparisons were made between computed values of source and load impedance. The constant‐volume‐velocity hypothesis was assumed to be valid for those cases where source impedance was much, much greater than load impedance. Plots of such impedances show that, for the cases investigated, this rarely occurred, except over certain frequency bands. With the exception of in‐the‐ear hearing aids, these results appear to contradict inferences made in the literature about the constant‐volume‐velocity nature of hearing aids.

ISSN:0001-4966    

DOI:10.1121/1.393294

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

A mathematical model of the compliant tube polymer hydrophone has been developed, which facilitates the evaluation of its low‐frequency electroacoustic sensitivity and maximum operating pressure. Developed by the Naval Underwater Systems Center/New London Laboratory (NUSC/NLL), this type of hydrophone is comprised of the compliant tube (an air‐filled tube of flattened oval cross section and closed ends), a plastic spacer plate which attaches to the flattened surface of the tube, and the piezoelectric polymer (PVF2) film. The PVF2film is bonded to the surface of the plastic plate. It is shown that the sensitivity is enhanced by the use of the spacer, rather than bonding the PVF2film directly to the flattened surface of the compliant tube. Moreover, there is an optimal spacer thickness that maximizes the hydrophone sensitivity. Numerical results are presented for a steel compliant tube polymer hydrophone. The theoretical model has been applied to the NUSC/NLL steel compliant tube polymer hydrophone, with good agreement between the predicted and experimental values for hydrophone sensitivity and maximum operating pressure.

ISSN:0001-4966    

DOI:10.1121/1.393295

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

Two different concepts of the Langevin radiation pressure which are ultimately due to Langevin and Brillouin are discussed. The measurement of the radiation force on an absorber at oblique incidence can be regarded as anexperimentumcrucisin this respect. Herrey’s experimental result, which is confirmed by the author’s observations, is in favor of Brillouin. Some fundamentals and limitations of our present knowledge of the Langevin radiation force in nonabsorbing fluids are considered.

ISSN:0001-4966    

DOI:10.1121/1.393296

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

The amplitude of wave V of the auditory brainstem response (ABR) has been found to vary in a manner consistent with the psychophysical critical band data. When the frequency separations between members of a tone pair, displaced symmetrically around some center frequency, exceed some critical value, the amplitude of wave V undergoes an abrupt increase. Specifically, tonal pairs straddling 2 and 4 kHz were studied; abrupt increases in wave V amplitude were generally seen when frequency separations were between 600 and 800 Hz for a center frequency of 4 kHz, and between 200–400 Hz for a 2‐kHz center frequency. These electrophysiologically derived estimates are in reasonable agreement with psychophysical values found in the literature.

ISSN:0001-4966    

DOI:10.1121/1.393297

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

The influence of vocalic context on various temporal and spectral properties of preceding acoustic segments was investigated in utterances containing [E♯CV] sequences produced by two girls aged 4;8 and 9;5 years and by their father. The younger (but not the older) child’s speech showed a systematic lowering of [s]noise and [th] release burst spectra before [u]as compared to [i] and [æ]. The older child’s speech, on the other hand, showed an orderly relationship of the second‐formant frequency in [E] to the transconsonantal vowel. Both children tended to produce longer [s]noises and voice onset times as well as higher second‐formant peaks at constriction noise offset before [i] than before [u]and [æ]. All effects except the first were shown by the adult who, in addition, produced first‐formant frequencies in [E]that anticipated the transconsonantal vowel. These observations suggest that different forms of anticipatory coarticulation may have different causes and may follow different developmental patterns. A strategy for future research is suggested.

ISSN:0001-4966    

DOI:10.1121/1.393298

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.393769

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.393301

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.393303

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP