摘要:

Subjects were required to distinguish among two‐component auditory stimuli of the formcosω1t+cos(ω2t+φ)[cf., J. H. Craig and L. A. Jeffress, “Effect of Phase on the Quality of a Two‐Component Tone,” J. Acoust. Soc. Amer.34, 1752–1760 (1962)]. The frequency ratio ω1:ω2was 2:3, and the only difference among stimuli presented in a given session was the phase φ. Stimuli were presented monaurally at low frequency (range 100 Hz–1 kHz) and high intensity (range 60–90 dB SPL). Stimuli were generated and the experiment was controlled by a Honeywell DDP‐516 computer. Subjects made dissimilarity judgments using the method of triadic comparisons, and they also made paired‐comparison judgments of subjective attributes, such as apparent pitch and timbre. The relationships between these subjective attributes and phase of the stimulus change systematically as stimulus frequency or intensity changes. Dissimilarity matrices obtained from the triadic comparisons can be related to pitch and timbre of the stimulus.

ISSN:0001-4966    

DOI:10.1121/1.1977760

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

In the course of attempting to recreate realistically the sounds of jet aircraft overflights, it was discovered that a monophonic recording of a jet takeoff or landing, when presented through a four‐channel system (one speaker in each corner of the room), gave the sensation that the sound was coming from a single source directly overhead. This seemed a rather interesting phenomenon, since the four speakers were below the level of the listener's head. A study was then conducted, using several 1‐oct wide bands of noise as well as some meaningful sounds, to determine more definitive aspects of this phenomenon. The results of these studies will be reported.

ISSN:0001-4966    

DOI:10.1121/1.1977767

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The extension of the upper frequency limit of the playback stylus is reviewed from a theoretical and measured review of the published work of C. R. Bastaians and subsequent additional data presented by J. White. From these apparent limits the discussion of the newly introduced high‐frequency playback techniques developed at Teldec are reviewed. [C. R. Bastiaans, “Factors Affecting the Stylus/Groove Relationship in Phonograph Playback Systems,” J. Audio Eng. Soc.15, 389–399 (October 1967); Offenlegungsschrift1574 489, German Patent Office, 10 September 1970).]

ISSN:0001-4966    

DOI:10.1121/1.1977771

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Biological change consequent on ultrasonic exposure may arise through three distinct modes: thermal, cavitational (including stable bubble), and “other.” The thermal mechanism is quite well defined and predictable. Wide divergencies occur between different authors on values of cavitation thresholds, but these may be due, in part, to differences in criteria used. Our results are reported for dependence of “stable cavitation” on intensity, frequency, pulsing parameters, ambient pressure, and nature of the medium (liquid, gel, or organized tissue). Evidence is reviewed for the existence of, and relevant thresholds for, other mechanisms that are effective in living cells and tissues irradiated by ultrasonic beams.

ISSN:0001-4966    

DOI:10.1121/1.1977776

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Measurement of the impulse response of live pinnae were made in an anechoic space. The responses of the near‐side and far‐side ears were recorded on paper punch tape for about 390 locations in the right hemisphere. Live and remote listening tests with single clicks and with noise bursts as stimuli were conducted. Interaural time differences were measured in 10° increments at 0° azimuth and at 0° elevation. Pinna impulse responses show a systematic change of structures as a function of azimuth and elevation. The localization data indicate that errors in elevation judgments and azimuth judgments are not correlated. These data suggest that separate mechanisms may be used to estimate azimuth and elevation. The importance to localization of the pinna transfer function, head motions, and interaural time differences are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1977780

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Summating potentials (SP) in response to tone bursts were measured from all three scalae of the first, second, and third turns of guinea pig cochleae. Both the intensity and frequency of the stimulus were varied over a wide range of values, and averaging techniques were used to obtain the summating potential. The scala media response (SM) was compared to the scala tympani (ST) and vestibuli (SV) responses, as well as to the potential gradient across the cochlear partition and the common potential of the two perilymphatic scalae. The former of these quantities is defined asDIF = (SV−ST)/2, while the latter asAVE = (SV+ST)/2[Dalloset el., Science170, 641–644 (1970)]. It was demonstrated that at any cochlear location the potential gradient across the cochlear partition (DIF) and the scala media response are best correlated in the dependence of response magnitude and polarity upon stimulus parameters. Aside from the similarities in the response patterns, some significant differences were also noted. Probably the most important of these is that the width of the characteristic negative summating potential bands in the vicinity of the best frequency for a given electrode location is greater in SM than when recorded from the perilymph with the differential electrodes. [Supported by grants from the National Institute of Neurological Diseases and Stroke.]

ISSN:0001-4966    

DOI:10.1121/1.1977785

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Certain differences in cochlear anatomy between the agoutiDasyprocta puctataand guinea pigCavia porcellusprovide an empirical test of models dealing with inner‐ear mechanics. The basilar membrane of agouti, for example, is about 60% longer and somewhat narrower than that of the guinea pig. Based on the work of von Békésy and others, velocity of the traveling wave should be greater in the agouti than it is in the guinea pig. In addition, a greater proportion of the basilar membrane of the agouti should be devoted to reception of higher‐frequency stimuli. The cochlea microphonic (CM) was used as the index of basilar membrane response in 18 agoutis and 12 guinea pigs. Scala media recordings were made from each turn, and differential recordings were made from each turn but the apex in both species. CM latencies to tone pips and clicks were measured. Sensitivity functions were also taken. As predicted by several models, latency per unit length of basilar membrane was shorter for agoutis than for guinea pigs. For each turn agouti sensitivity to low‐frequency tones was less and to high‐frequency tones greater than was that of the guinea pig.

ISSN:0001-4966    

DOI:10.1121/1.1977787

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The rate of response of single fibers in the cat auditory nerve to tone bursts was measured prior to and following 1‐min exposure to a tone at the fiber's characteristic frequency. Measurements were made for several levels of the exposure tone. Ten test bursts, at near threshold levels, preceded exposure and 90 followed it. In some runs the test bursts were omitted so that the recovery of spontaneous activity could be studied. The last postexposure burst was followed by a silent period of at least 80 sec before the next test. Following exposure, response rate to the test bursts was less than the pre‐exposure value. Response rate recovered to at least 80% of the pre‐exposure level within 2–15 sec after exposure. Complete recovery of the rate to the pre‐exposure level occurred within 2 min. Both the amount of rate reduction and the time course of recovery could depend on exposure level. [Supported by the National Institute of Neurological Diseases and Stroke and the U. S. Air Force Office of Scientific Research.]

ISSN:0001-4966    

DOI:10.1121/1.1977792

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

A new concept in electromagnetic vibration exciter design, in which the entire dynamic portion of the vibration exciter can be quickly changed, provides optimization of performance characteristics for specific applications. Since a head with the specific performance characteristics needed for the job can be selected, it is no longer necessary to use a compromise design. The performance characteristics discussed include those applicable to 200gtesting, the testing of large objects where high side load capability and a rigid table are essential, the measurement of structural modes, impedances, and transfer functions, and confirmation calibration of accelerometers and other transducers. The design objectives and solutions are presented for the stiff highly damped suspension systems that make interchangeable heads possible. The moving element skeletons of five different heads are described in detail, showing how the different performance criteria for various applications are achieved. Included in the program are three different vibration exciter sizes with four or five heads for each.

ISSN:0001-4966    

DOI:10.1121/1.1977797

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

This work shows the effect of the drive point impedance of a finite acoustic system on the power delivered by a realistic source. At low frequencies when the modal overlap of the system is small, the frequency‐averaged power delivered by the source can be much less than the power which the source would deliver to an equivalent semi‐infinite system. An analysis of the power flow into a finite one‐dimensional wave tube is used to explain the observation that broad‐band high‐intensity acoustic drivers deliver less low‐frequency power to small reverberation chambers than they deliver to progressive wave tubes. The analysis indicates that the modal overlap also plays a central role in the determination of the ratio of space‐averaged to drive point response.

ISSN:0001-4966    

DOI:10.1121/1.1977804

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP