摘要:

Naturally‐isolated living cells were subjected to ultrasonic vibration by means of the tip of a steel needle applied directly to the cell surface or inserted into a drop of a suspension of cells in sea water. The needle was machined into the tip of a stainless‐steel cone, and the base of the cone was glued to one end of an electroded and polarized barium titanate hollow cylinder. This composite transducer was driven at its resonant frequency of approximately 85 000 cps. Ultrasound applier to the surfaces of egg cells of marine invertebrates produces rotation, translation, deformation, and fragmentation of the nucleoli; rotation and deformation of the nuclei; acoustic streaming of nucleoplasm and cytoplasm; and deformation of the cellular surface and fragmentation of the cell. Cells and intracellular bodies are often attracted to the sound source as a result of acoustic‐radiation pressure, and, especially for whole cells in suspension, this attractive tendency is typically superposed on a tendency of the body to take part in acoustic streaming of the surrounding medium. Some aspects of the motion can be accounted for in terms of presently available theory of nonlinear acoustics. Information on the physical properties of nucleolus, nucleoplasm, and cytoplasm is gained from use of this sonic technique.

ISSN:0001-4966    

DOI:10.1121/1.1910235

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Temporary threshold shifts (ITS) in pure tone hearing acuity are reported for 15 subjects exposed in separate 15‐min periods to taped impact sounds [played back at 124‐ to 127 dB peak sound‐pressure level (SPL)], to three levels of filtered (75‐ tn 1200 cps) steady‐state noise (90, 100, 110 dB SPL), and to combinations of the recorded impact sounds with each level of the steady‐state noise. TTS's from all such exposures were typically small, with the largest shifts occurring in the 1000‐ to 3000 cps frequency range. When combined with 90‐ and 100 dB steady‐state noise, the impacts caused less threshold shift than when presented alone. Such TTS reductions were believed due to the relatively greater ability of the steady‐state noise to arouse and sustain the acoustic reflex with its consequent sound‐attenuation effect. The addition of the 110 dB steady‐state noise did not induce a similar result quite possibly because this exposure, by itself, caused threshold shifts equal to or exceeding those of the impact sounds. More‐effective stimulation of the acoustic reflex was believed responsible for findings showing less TTS for combined impact/steady state noise than from exposure to just the steady‐state component of the combination. Indirect measures of acoustic‐reflex response [contralateral remote masking (CRM)]generally indicated that those ears with a strong reflex response show less noise‐induced shift. Correlations between TTS from impact and from steady‐state noise for the subject group indicated some degree of positive correspondence limited to frequencies of of 2000 cps and below and strongest for those subjects with a poor reflex response as shown by their CRM data.

ISSN:0001-4966    

DOI:10.1121/1.1910236

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

In chinchilla ears, between 1000 and 3000 Hz, the common one‐half frequency subharmonic is not present. Instead, pairs of odd‐fractional subharmonics are seen. These distortion components appear at threshold only in specific frequency relations with the fundamental. Above threshold, both the frequency and the magnitude of the subharmonic depend on the stimulus intensity. With direct mechanical stapes stimulation and with various probe‐tone experiments, it was shown that the odd‐fractional subharmonics originate in the inner ear. The phenomenon of subharmonic squelch effect was described.

ISSN:0001-4966    

DOI:10.1121/1.1910237

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

This paper reports some preliminary results of an attempt to apply the equalization and cancellation (EC) model of binaural unmasking to data on interaural just‐noticeable differences (jnd's). The interaural dimensions that are considered are time, amplitude, frequency, and decorrelation.

ISSN:0001-4966    

DOI:10.1121/1.1910238

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Microelectrodes were inserted into the three scalae of the first turn, and resistance measurements were fitted to a model having six pathways. The six pathways with average resistance values are (1) blood vessels inside the cochlea to the outside of the bulla—1.6kΩ, (2) blood vessels inside the cochlea to scala tympani—0.6kΩ, (3) blood vessels inside the cochlea to scala vestibuli—0.8kΩ, (4) blood vessels inside the cochlea via the stria vascularis to scala media—13kΩ, (5) scala media direct to scala tympani (organ of Corti)—24kΩ, (6) scala media direct to scala vestibuli (Reissner's membrane) 46kΩ. There was no indication of a need to include a direct pathway from scala tympani to scala vestibuli. The “length constant” of scala media in the first turn is about 2.0 mm. The resistance changes due to moderate sound were found to be small, but measurable. Changes of resistance with anoxia showed first a decrease and then an increase in the resistance from scala media to ground.

ISSN:0001-4966    

DOI:10.1121/1.1910239

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The relationship between sound and cochlear potentials is considered in the light of von Békésy's observations of movement of the cochlear partition and Davis' variable‐resistance theory of hair‐cell function. An equation is derived relating hair angle to basilar‐membrane movement. The equation isφ = arcot (Yα+cotφ0)where φ is the hair angle and α is proportional to basilar‐membrane movement. φ0is the resting hair angle.Yis the ratio of the distance between basilar membrane and hair cell apex to the distance between tectorial membrane and hair‐cell apex. It is shown that the sigmoidal shape of this function leads to a linear dependence of microphonics on sound intensity, generation of harmonics, and production of positive and negative summating potentials by inner and outer hair cells, respectively. The behavior of the cochlear potentials, including the effect of sound pressure in reversing summating potential polarity, effect of cochlear pressure changes, and reversal of summating potential polarity with anoxia, is also accounted for. A mechanical model of the organ of Corti, used to illustrate our theory, is described, together with results obtained from the model.

ISSN:0001-4966    

DOI:10.1121/1.1910240

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Psychometric functions were obtained for several interaural phase combinations with both continuous and burst masking noise. In the burst conditions, the signal (400 cps, 125 msec) and the wide‐band masker (45 dB/cycle) were gated simultaneously; in the continuous conditions, only the signal was gated. Performance on burst N0‐S0 was only about 0.5 dB worse than that on continuous N0‐S0, but the masking‐level differences (MLD's) for N0‐Sπ Nπ‐S0, N0‐Sm, and Nπ‐Smwere 4–6 dB smaller with burst than with continuous noise. In an additional experiment, the noise burst (N0) was gated 0, 75, 150, 250, 400, 600, and 1000 msec before the onset of the signal (Sπ). These MLD's increased gradually between 0 and 600 msec and then leveled off at approximately the value obtained with a continuous masker. A single‐intervalYES‐NOprocedure was used in these experiments. When two‐alternative forced choice was used, the difference between continuous and burst noise was considerably diminished.

ISSN:0001-4966    

DOI:10.1121/1.1910241

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The frequency response of stapedial‐footplate vibration during sound conduction was measured on fresh cadaver specimens. Specially designed and adapted instruments made these measurements possible at sound levels lower than those causing discomfort to living subjects (84 114 dB), and with a continuous frequency sweep between 100 cps and 10 kcps. The results show a similarity with the curves of subjective ear sensitivity, suggesting a dependence of the over‐all sensitivity of the ear on the middle‐ear frequency response. Linear increase of vibration amplitude with sound level was found to exist up to around 104 dB; above this sound level, there is a gradual limiting of the stapedial excursions. Speculations on energy transfer from the middle to the inner ear showed nearly optimal matching between them. The influence of the aging process of the specimens is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1910242

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Electrical stimulation of the crossed olivocochlear bundle in anesthetized cats reduces auditory‐nerve responses (N1) if the acoustic stimuli are at low sound‐pressure levels but does not produce detectable changes in neural responses for click stimuli more than 60 to 70 dB above visual‐detection level forN1. When the sound‐pressure levels of high‐frequency (10 000‐Hz) and low frequency (400‐Hz) transient acoustic stimuli were matched according to a physiological criterion, the neural response to the high‐ frequency stimulus was reduced more by olivocochlear bundle stimulation than the response to the low‐frequency stimulus. These result, suggest certain characteristics for the mechanisms which influence the activity of single auditory‐nerve fibers.

ISSN:0001-4966    

DOI:10.1121/1.1910243

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The theory of an experimental procedure that can be used to measure specific acoustic impedance is presented in this paper. No moving parts are required. Only two measurements need be made. A sequence of simple calculations is presented for reduction of these data.

ISSN:0001-4966    

DOI:10.1121/1.1910244

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP