摘要:

Research has demonstrated that while many aspects of language processing are lateralized to the left cerebral hemisphere in man, perception of pitch differences is not. We have conducted experiments in the dichotic listening paradigm to determine whether speakers of tone languages show a right ear advantage in processing contrasting “tones.” Three sets of stimuli were used: randomly paired combinations of five Thai words differing only in tone; paired lists of five Thai words contrasting only in initial segment; the five Thai tones hummed to contrast only in pitch level and direction. Thai speakers were used as subjects. The preliminary results show that for Thai speakers, there is a right ear preference for pitch stimuli only when the contrasting pitches represent linguistic “tones.” Consonantal discrimination and “hums” were processed as expected: a right ear preference for consonants, a left ear preference for nonlinguistic pitch. [This research was supported in part by a U. S. Public Health Services (NIH) Grant, and in part by an Office of Naval Research Contract.]

ISSN:0001-4966    

DOI:10.1121/1.1982446

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

SKAT is part of an automated, self‐administered preschool screening battery for vision, IQ, and readiness. SKAT was designed to detect educationally significant hearing and discrimination problems. Sixteen CVC words were selected for familiarity to preschoolers. The words were grouped into sets of four. All words in a given set had the same vowel; consonants differed. The four pictures for a set were displayed together on a rear‐projection screen. A response button was located beside each picture. Words were presented through TDH‐49 earphones. To reduce testing time, conditioning was limited to naming each picture once. When testing began, the S was instructed to press the button next to, e.g., “pot.” A new display and new word were presented when S responded, or after 6 sec. Twelve words per ear were presented at varying intensities: four each at 55, 50, and 45 dB SPL, randomly. Standard puretone (Malco Audiometer) screening was administered to 61 Ss,K‐2. Each S self‐administered SKAT in 3.5 min, average time. Six Ss (10%) failed both procedures. Three (5%) failed SKAT, but passed pure tone. In similar studies, more false negatives and false positives have been reported for the VASC and Fading Numbers Test.

ISSN:0001-4966    

DOI:10.1121/1.1982449

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Monaural chinchillas (15) were exposed to 50 impulses of either 158, 615, or 175 dB peak SPL. The impulses were generated by a spark‐gap source, which produced an impulse with a 40‐μsecAduration. Quiet thresholds were measured at 0.25, 0.5, 1, 2, 4, and 8 kHz, using the averaged evoked response technique. Recovery was monitored for 31 days and then the animals were sacrificed and their cochleas were analyzed using the surface preparation technique. The three exposures produced virtually no permanent threshold shifts (PTS) with the exception of 10–30 dB PTS in one animal in each of the 165‐ and 175‐dB groups. However, hair cell losses were seen in all three groups. The cochleagrams varied from low level scattered losses to lesions of the OHC that spanned a 4‐mm stretch in the base of the cochlea. The IHC losses were considerably smaller and more restricted. The audiograms do no necessarily reflect the state of the cochlea.

ISSN:0001-4966    

DOI:10.1121/1.1982459

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The cochleas of the chinchillas exposed to the four noise conditions described in the previous abstract were examined using the surface preparation technique. The animals (six) exposed to the continuous noise alone, had essentially normal hair cell populations. The animals (five) exposed to the 158‐dB peak impulse had hair cell losses that ranged from a scattered low level loss to approximately a 4 mm loss of OHC in the base of the cochlea. IHC losses were considerably smaller. The animals (six) exposed to the interrupted combination had nearly the same range of hair cell losses as seen in the 158‐dB group, with the exception of one animal that had a large (8 mm) discrete loss of OHC and IHC. The superimposed combination produced the most severe hair cell lesions with five of the six animals showing nearly 100% losses of OHC and IHC extending throughout the basal one‐third to one‐half of the cochlea. The audiometric and histological findings agree in showing that the superimposed combination of the two “safe” noises produces traumatic effects that more than exceed the additive effect of either component. The existing DRC do not provide guidlines for such combinations.

ISSN:0001-4966    

DOI:10.1121/1.1982461

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Optimal control theory is employed to analyze the transient response of discrete linear systems to forcing functions whose dependence on time is not known, but which lie within specified bounds. Attention is focused on the complete determination of the forcing function that will induce (a) maximum displacement of any specified mass element; (b) maximum relative displacement of any two adjacent masses; and (c) maximum acceleration of a given mass. Undamped mechanical systems with an arbitrary number of degrees of freedom are considered wherein only a single forcing function acts. In general, the desired forcing function is found to be a bang‐bang type function, that is, a function which switches from the upper to the lower bound and vice versa at certain instants of time. The general procedure for finding these switching times is presented.

ISSN:0001-4966    

DOI:10.1121/1.1982465

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The fundamental equation of statistical energy analysis (SEA) states that the average power flow between two coupled vibrating systems is proportional to the difference in their average modal energies. Under certain circumstances, one can estimate the proportionality constant by modifying system boundary conditions on the separated systems and calculating or measuring changes in the systems. Newland's estimate, based upon blocking part of the system, is reexamined and limitations are discussed. Three alternative methods which circumvent blocking are presented. They are based, respectively, upon (1) natural frequency shift due to addition of mass; (2) mechanical input impedance; and (3) mean square velocity response at the excitation point due to random excitation. The new methods were applied to predict power flow in experiments on coupled beams and on coupled plates. One or both parts of the coupled structures were then excited by external random sources, and power flow through the coupling was measured directly as a product of force with velocity. The fundamental SEA relation was supported by the measurements, which included the null power point where the difference in average modal energies was zero. Measured and predicted proportionality constants are compared. [This work was supported in part by the National Aeronautics and Space Administration.]

ISSN:0001-4966    

DOI:10.1121/1.1982472

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Acoustic volume scattering measurements made during the 1971 winter season at 18 deep‐water stations north and east of Auckland, New Zealand, are presented in terms of volume scattering strength andcolumnstrength. (Columns extend from near surface to a depth of 1000 yds.) Both pulse‐type data, at 5.0 and 12 kHz, and explosive‐source data were obtained. At a given frequency, there is little station‐to‐station change incolumnstrength over the12‐octbands from 1 to 20 kHz. Typically,columnstrength rises sharply from 1 kHz to a maximum at 5 or 6 khz followed by a slight droop and another maximum at 16 kHz. Values fall in the range −40 to −70 dB. With one exception, night column strengths are higher than day values; this day‐to‐night difference has a maximum in the neighborhood of 3 kHz. The pulse results, expressed as volume scattering strength versus depth, also show station‐to‐station similarities; the principal scattering layers occur at about the same depths, andcolumnstrengths do not differ greatly. The distribution of volume scattering strengths with depth reveals distinguishing station‐to‐station differences not provided by the explosive data.Columnstrengths obtained from pulse data are in satisfactory agreement with those obtained from explosive measurements. Comparisons show that scattering levels off New Zealand are as high or higher than those observed in other North and South Pacific areas.

ISSN:0001-4966    

DOI:10.1121/1.1982478

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Long‐term (one‐year) open ocean measurements of ambient acoustic noise were made in the N.E. Pacific Ocean using instrument packages placed on seamounts. The seamounts Cobb [summit 15 fathoms (f)], Union (summit 160 f), and Bowie (summit 16 f), extended over612°of latitude in a near N‐S direction. Packages were placed on seamounts Cobb and Bowie on terraces at about the 110‐f level and on Union near the summit at about the 170‐f level. Averaged 4‐min samples of noise level in the 150‐ to 300‐Hz frequency baud were obtained once per hour and recorded as a bar graph on strip paper chart. Usable data yield was about 50%. The data are presented in the form of histograms of frequency of occurrence of noise level in 5‐dB intervals by months. There appears to be about a 4‐dB increase in noise level in the band in the winter months. A brief description of the instrument package and the technique used for placement and recovery will be given.

ISSN:0001-4966    

DOI:10.1121/1.1982491

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Acoustic sampling of various fish stocks and the acoustic characteristics of fish targets are being investigated as part of the Marine Acoustics Program at the University of Washington. An important outgrowth of this research is the development of a free‐floating acoustic system which is being used to help index the North Pacific salmon population. This is an uplooking system which operates at 250 kHz. Average target size of the migrating salmon is about − 30 dB within the aspect angles encountered in the sample volume. Acoustic source level and TVG receiver sensitivity were adjusted for that average size, but a fairly wide range of target‐size fluctuation can be accommodated (±10–15 dB). Studies of relative abundance indicate that the population density in particular areas is related to the spawning migration to Bristol Bay, Alaska, the following year thus providing an index of population abundance [D. E. Rogers, Fish Rec. Inst. Circ. ♯70‐7 (1970)]. A second acoustic system is now being developed for use in Bristol Bay to generate population data upon which to base the day to day management of the fishery so that catch and escapement are optimized.

ISSN:0001-4966    

DOI:10.1121/1.1982501

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Spoken integers between 0 and 999 (e.g. “three hundred and seventy two”) were recorded by four speakers. For each utterance, a measure of the waveform amplitude (called the envelope) and pitch period estimates were recorded and plotted. It is shown that these two correlates can be used to predict word and syllable boundaries within each spoken integer. These junctural correlates also reflect the semantic structure of the integers, so that both multiplication and addition operations are represented in the spoken number. Each boundary is also assigned a likelihood factor. These junctural determinations are determined without any use of segmental information (such as spectral estimates), and are directly related to the structure of the utterance.

ISSN:0001-4966    

DOI:10.1121/1.1982561

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP