• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Acoustics Research Letters Online

Search Issue | RSS Feeds RSS
Previous Issue

Oct 2003

Volume 4, Issue 4, pp. 112-134

FREE

Ringed seal densities and noise near an icebound artificial island with construction and drilling

Valerie D. Moulton, W. John Richardson, Michael T. Williams, and Susanna B. Blackwell

ARLO Volume 4, Issue 4, pp. 112-117 (July 2003); (6 pages) | Cited 4 times

Online Publication Date: 21 Jul 2003

Full Text: | Download PDF

Show Abstract
A monitoring program documented densities of ringed seals, Phoca hispida, before and during development of the Northstar oil field in the central Alaskan Beaufort Sea. Aerial surveys of seals on landfast ice were conducted during the springs of 1997 to 1999 (pre-construction) and 2000–2001 (construction and drilling). Acoustic and vibration data were acquired during the ice-covered seasons of 2000 and 2001. Underwater sounds, in-air sounds, and iceborne vibrations from Northstar were above background levels to distances of 1–5, 0.5–4, and 1–4 km, respectively. However, seal densities close to Northstar in 2000 and 2001 were not reduced relative to those farther away or during the 1997 to 1999 period. © 2003 Acoustical Society of America.
Show PACS
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
FREE

Visualization of edge diffraction

Ville Pulkki and Tapio Lokki

ARLO Volume 4, Issue 4, pp. 118-123 (July 2003); (6 pages) | Cited 1 time

Online Publication Date: 21 Jul 2003

Full Text: | Download PDF

Show Abstract
The acoustics of a room can be visualized by plotting image sources at the positions where they occur. Recently, the image-source method has been extended to include edge diffraction. A visualization technique for image source method including diffraction is presented. As examples, first-order diffraction in a stage-house, and second-order diffraction around a loudspeaker enclosure are visualized. © 2003 Acoustical Society of America.
Show PACS
43.55.Ka Computer simulation of acoustics in enclosures, modeling
43.20.El Reflection, refraction, diffraction of acoustic waves
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
FREE

Effects of high presentation levels on recognition of low- and high-frequency speech

Michelle R. Molis and Van Summers

ARLO Volume 4, Issue 4, pp. 124-128 (July 2003); (5 pages) | Cited 11 times

Online Publication Date: 21 Jul 2003

Full Text: | Download PDF

Show Abstract
Speech recognition accuracy decreases when presentation levels are raised above moderate levels. This “rollover” effect at high levels has generally been viewed as a broadband phenomenon, influencing low- and high-frequency processing similarly. In the current study, listeners with normal hearing identified lowpass and highpass sentences at a range of presentation levels to determine whether rollover effects might be greater in either region. Recognition scores showed larger and more consistent decreases at high levels (i.e., greater rollover) for high-frequency speech materials. The results are consistent with both physiological and psychoacoustic data suggesting that cochlear processing shows greater level dependence in basal regions tuned to high frequencies than apical, low-frequency regions. Predictions of speech intelligibility by methods such as the Speech Intelligibility Index [ANSI, 1997] may be improved if the frequency-dependence of rollover is considered. © 2003 Acoustical Society of America.
Show PACS
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.71.Gv Measures of speech perception (intelligibility and quality)
FREE

Investigating the role of infant-directed speech with a computer model

Bart de Boer and Patricia K. Kuhl

ARLO Volume 4, Issue 4, pp. 129-134 (August 2003); (6 pages) | Cited 19 times

Online Publication Date: 14 Aug 2003

Full Text: | Download PDF

Show Abstract
A computer model (expectation maximization of a mixture of Gaussians) is used to learn the positions of vowel categories from two sets of recorded words. The number of vowels is known beforehand. The results show that vowel positions learned on the basis of infant-directed (ID) speech correspond better to those in the input than those learned on the basis of adult-directed (AD) speech. © 2003 Acoustical Society of America.
Show PACS
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
43.71.Ft Development of speech perception
43.72.Ne Automatic speech recognition systems
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close