摘要:

This paper reports a comprehensive experimental investigation, utilizing ultrasonic techniques to study the kinetics of proton‐transfer reactions in nondilute aqueous solutions of amino acids. Ultrasonic absorption and velocity measurements in the range of frequencies 10–130 MHz and ofpH 0.96–11.6 are analyzed in terms of single relaxation behavior. Activity coefficients are calculated by three methods; the method based upon standard ionic radii and the mean dielectric constant of the solutions is found to yield the most acceptable estimates. The dependencies of rate constants upon initial concentration of solute, ionic strength, and temperature are displayed in the range 0.25M–1.0M, 0.25M–1.0M, and 22°–37°C, respectively. It is concluded that proton‐transfer reactions at amino and carboxyl groups cannot be responsible for significant contributions to the total ultrasonic absorption coefficient of blood in the physiological range ofpH.

ISSN:0001-4966    

DOI:10.1121/1.1912494

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Pure‐tone masking‐tone thresholds were obtained for a bottlenosed porpoise The masking‐tone frequency was 70 kHz. Two masking levels were used, 40 and 80 dB above threshold. The shapes of the masking curves were very similar to those obtained from human subjects at much lower frequencies.

ISSN:0001-4966    

DOI:10.1121/1.1912496

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Moray's [J. Acoust. Soc. Amer.47, 660–661(L) (1970)] experiment on binaural time sharing leaves several questions unanswered concerning actual differences between single‐channel and binaural detectability. We cite recent evidence showing no decrement in the detectability of signals presented simultaneously to each ear, when the signals are of short duration and the same frequency.

ISSN:0001-4966    

DOI:10.1121/1.1912497

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Cochlear models indicate that basilar membrane displacement in the basal region approximates a first‐derivative transform of the input signal. Evidence regarding acoustic transients and their cochlear microphone equivalents in the guinea pig is cited to demonstrate this conversion and suggests the plausibility of the observations derived from models.

ISSN:0001-4966    

DOI:10.1121/1.1912499

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The characteristic tone of a stiff bar, clamped at one end and subjected to a strike impulse, has been calculated when the vibrations are detected by use of a condenser microphone. Such a geometry is used in percussion instruments which simulate the sound of a bell. As one consideration, it is necessary to include the position and length of the condenser plate as well as the position of the strike point to reproduce generally the relative voltage for each vibrational mode, as is experimentally observed.

ISSN:0001-4966    

DOI:10.1121/1.1912500

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The effect of changing the fundamental frequency on the perception of two‐formant vowels and h_d words has been investigated. Raising the fundamental by an octave caused a rise in the mean ofF1 of about 5% and a rise in the mean ofF2 of about 2%. Isolated and context vowels gave similar results except that the context vowels were recognized more consistently.

ISSN:0001-4966    

DOI:10.1121/1.1912501

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The sound spectra of the voiceless hard and soft Russian fricatives have been studied in various vowel contexts and with a population of five different speakers (three men, two women). The acoustic characteristics of the fricatives are described in terms of distributions in theFC,FL‐plot, whereFCis the frequency of the centroid of a short‐time spectral section of the voiceless part of a fricative, and whereFLis the frequency of the very beginning of the second formant transition from a fricative to a vowel. It is shown that the proper classification of the fricatives requires the self‐normalization procedure, because of considerable differences which occur between the same fricatives spoken by different speakers. Results obtained from the study confirm the efficiency of the statistical method of self‐normalization for the classification of the fricatives. The method was suggested earlier by the author for the classification of vowels.

ISSN:0001-4966    

DOI:10.1121/1.1912502

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Mating‐call intensities of five species of Australian anuran amphibians were measured under natural conditions. The sound‐intensity values were consistent within species, and ranged from 88 dB forCrinia parinsigniferato 103 dB forLimnodynastes tasmaniensis(0 dBre0.0002 dyn/cm2) at a distance of 50 cm. On the basis of published hearing threshold data, the maximal effective propagation distances were estimated forCrinia parinsigniferaandHyla ewingi; these were 4 m and 100 m, respectively.

ISSN:0001-4966    

DOI:10.1121/1.1912503

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The acoustic absorption of liver cell nuclei has been determined at frequencies from 1 to 10 MHz. The results, if expressed in terms of sound absorption per weight percentage of protein content, indicate that this specific absorption varies from one type of protein to another.

ISSN:0001-4966    

DOI:10.1121/1.1912504

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP