ARTICLES

Differential Sensitivity of the Ear for Underwater Pure Tones
K Kuramoto, S Kuwahara, K Oimatsu, S Yamaguchi

The Microflown: An Acoustic Particle Velocity Sensor
H-E de Bree

Vocal Tract Resonances: A Preliminary Study of Sex Differences for Young Australians
T Donaldson, D Wang, J Smith & J Wolfe

Railway Bonus for Sounds Without Meaning?
H Fastl, M. Fruhmann & S. Ache

The Statistical Estimation of the Attenuation of Impulse Peak Levels with Respect to Distance
W Williams

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D Watkins & M Burgess

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DIFFERENTIAL SENSITIVITY OF THE EAR FOR UNDERWATER PURE TONES

Vol. 31, No. 3 pp 87 - 90 (2003)
ABSTRACT: As a part of the research for constructing an underwater transmission system to divers, differential sensitivity of the ear in water to sound intensity and frequency was examined by listening experiments in a water tank. Although the value of minimum audible field (MAF) in water was considerably different from that in air, it is found that the dependence of differential sensitivity at the same sensation level (SL) is almost the same both in water and in air. Resolution of the auditory sense (i.e. number of steps in distinguishable sound) was estimated in the underwater auditory area by using existing results in air.

THE MICROFLOWN:AN ACOUSTIC PARTICLE VELOCITY SENSOR

Vol. 31, No. 3 pp 91 - 94 (2003)
ABSTRACT: The Microflown is an acoustic sensor directly measuring particle velocity instead of sound pressure, which is usually measured by conventional microphones. Since its invention in 1994 it is mostly used for measurement purposes (broadband 1D and 3Dsound intensity measurement and acoustic impedance). Possible applications are near and far field sound source localization, in-situ acoustic impedance determination and a non-contact method to measure structural vibrations (an alternative for a laser vibrometer). The Microflown, invented only a few years ago, is now commercially available.

VOCAL TRACT RESONANCES: A PRELIMINARY STUDY OF SEX DIFFERENCES FOR YOUNG AUSTRALIANS

Vol. 31, No. 3 pp 95 - 98 (2003)
ABSTRACT: We report direct measurements of the first two resonance frequencies of the vocal tracts of young women university students producing the vowels of Australian English. The resonances are determined from the response of the tract to a broad band, external, acoustic source. From these data we construct a vowel resonance map for these Australian women and compare it with the corresponding data for a sample of young Australian men, also university students.

RAILWAY BONUS FOR SOUNDS WITHOUT MEANING?^*

Vol. 31, No. 3 pp 99 - 101 (2003)
ABSTRACT: At same A-weighted energy-equivalent level, railway noise frequently is preferred to road traffic noise. This effect often is called railway bonus. Among possible reasons for the railway bonus, differences in spectrum, time structure, and meaning of sound are discussed. In order to largely "neutralize" the meaning of sound, a procedure was proposed as follows: the sound, e.g. railway noise, is analyzed by Fourier-Time-Transform (FTT) and - after spectral broadening - re-synthesized by inverse FTT. The procedure has the advantage that the loudness-time functions of original and neutralized sound are identical, but the meaning of the sound is removed. In psychoacoustics experiments, for original sounds of railway versus road traffic noise, a railway bonus could be ascertained. If for the same sounds, when deprived from their meaning, also a railway bonus would show up, then the meaning of sound would contribute to the railway bonus much less than differences in spectrum and/or time structure. If, on the other hand, the meaning of sound would be a dominant factor for the railway bonus, with neutralized sounds no railway bonus should show up. Results of corresponding psychoacoustics experiments are reported and discussed in view of the psychophysical method used.

THE STATISTICAL ESTIMATION OF THE ATTENUATION OF IMPULSE PEAK LEVELS WITH RESPECT TO DISTANCE

Vol. 31, No. 3 pp 103 - 107 (2003)
ABSTRACT: This paper presents a summary of experimental work carried out on impulsive noise propagation over distances up to 3.2 kilometers. The average attenuation of the maximum peak level (MAXP) is examined with respect to distance for all times of day and widely varying geographical and meteorological conditions. Formulae for predicting impulse attenuation are derived from the data using both spherical spreading and a curve of best-fit method. Possibly more important is the fact that the MAXP levels measured at any one location can lie over a wide range for example, up to 50 dB at 3.2 km. This has important implications for the prediction of annoyance and indicates that more consideration should be given to the statistical spread of results derived from experimental work.