Volume 103, Issue 5, May 1998
Index of content:
- SELECTED RESEARCH ARTICLE 
The force between two parallel rigid plates due to the radiation pressure of broadband noise: An acoustic Casimir effect103(1998); http://dx.doi.org/10.1121/1.422744View Description Hide Description
Theoretical and experimental results are presented for the force law between two rigid, parallel plates due to the radiation pressure of broadband acoustic noise. The noise is in the band of 5–15 kHz and has an intensity of 133 dB ). Excellent quantitative agreement is shown between theory and experiment. These results constitute an acoustic analog for the Casimir effect, which is the force experienced by two closely spaced uncharged conducting plates due to the quantum electromagnetic zero-point field. In contrast to this case, however, band-limited noise can cause the force to be attractive or repulsive as a function of separation between the plates.
103(1998); http://dx.doi.org/10.1121/1.422745View Description Hide Description
Two experiments were carried out to determine how manipulating the compression ratio and release time of a single-band wide dynamic range hearing aid affects sound quality. In experiment I, compression ratio was varied over the range from linear to 10:1 (low compression threshold, attack time=5 ms, release time=200 ms). In experiment II, compression ratios of 1.5, 2, and 3:1 were combined with release times of 60, 200, and 1000 ms (attack time=5 ms). Twenty listeners with sensorineural hearing loss rated the clarity, pleasantness, background noise,loudness, and the overall impression of speech-in-noise (Ventilation, Apartment, Cafeteria) processed through a compression hearing aid. Results revealed that increasing compression ratio caused decreases in ratings on all scales. Increasing release time caused ratings of pleasantness to increase, and ratings of background noise and loudness to decrease. At the 3:1 compression ratio, increasing the release time caused increases in ratings of clarity, pleasantness, and overall impression, and a decrease in background noise. Significant correlations were found between scales. Regression analysis revealed that the contributions of the scales of clarity, pleasantness, background noise, and loudness to the prediction of overall impression differed as a function of the competing noise condition.