Volume 118, Issue 6, December 2005
Index of content:
- NOISE: ITS EFFECTS AND CONTROL 
118(2005); http://dx.doi.org/10.1121/1.2118327View Description Hide Description
This article presents the results of a noise survey at Johns Hopkins Hospital in Baltimore, MD. Results include equivalent sound pressure levels as a function of location, frequency, and time of day. At all locations and all times of day, the indicate that a serious problem exists. No location is in compliance with current World Health Organization Guidelines, and a review of objective data indicates that this is true of hospitals throughout the world. Average equivalent sound levels are in the range for , , and averaging time periods. The spectra are generally flat over the octave bands, with higher sound levels at lower frequencies, and a gradual roll off above . Many units exhibit little if any reduction of sound levels in the nighttime. Data gathered at various hospitals over the last indicate a trend of increasing noise levels during daytime and nighttime hours. The implications of these results are significant for patients, visitors, and hospital staff.
118(2005); http://dx.doi.org/10.1121/1.2118347View Description Hide Description
Underwater and in-air recordings were made from a boat anchored near Prudhoe Bay, Alaska, while a Griffon 2000TD hovercraft drove by at or near full power on four passes. At the closest point of approach (CPA, ), underwater broadband levels reached 133 and : at depths of 1 and , respectively. In-air unweighted and A-weighted broadband levels reached 104 and : , respectively. The hovercraft produced sound at a wide range of frequencies. Both underwater and in air, the largest spectral peak was near , which corresponded to the blade rate of the thrust propeller. In addition, the spectral composition included several harmonics of this frequency. The shaft or blade rate of the lift fan was barely detectable underwater despite its proximity to the water. The hovercraft was considerably quieter underwater than similar-sized conventional vessels and may be an attractive alternative when there is concern over underwater sounds.