A study was conducted to determine the enhancement in convection heat transfer that could be achieved using the corona wind over a range of stream velocities. A heated flat plate mounted in a flow channel was placed in a Mach-Zehnder interferometer. Corona wires were placed above the active plate surface. Data were taken over a range of stream velocities. The results showed the expected large increase in heat transfer at low velocities and that this gain in heat transfer decreased to zero at high stream velocities.

Nationwide Children's Hospital was interested in understanding speech communications: in their operating rooms and between the parents/child and the doctor in pre-operative rooms. Long-term hearing loss of the staff was of secondary interest. Before a comprehensive project was proposed, data in a single OR to gain some experience was conducted. A SLM was programmed to measure the following during 15 s intervals: overall A-weighted equivalent energy sound level, A-weighted equivalent energy sound level in octave bands from 16 to 16 kHz, and peak un-weighted level during the interval. Reverberation was also measured by an impulsive method. Measurements were made for 23 consecutive hours. The data were downloaded for analysis. It was concluded that (1) adding some absorption around the top of the walls would improve SI, (2) good SI is only possible with a high vocal effort, and (3) long term hearing loss is very unlikely. Follow up topics before a comprehensive project is proposed were (1) try other reverberation methods, (2) study more rooms while a variety of surgical procedures are performed, (3) identify the source and duration of peaks levels, and (4) investigate other measures of SI.

The department has a 13×7×8 ft fully anechoic chamber whose commissioning records were misplaced. The graduate acoustics class measured the acoustics of the chamber from 250–2000 Hz in preparation for future research projects. The focus was on the far field and its limits (near field, and approach to wedge tips). Four groups of students made measurements along the same path. The difference in the levels at a location from that at a reference location was calculated. The mean and standard deviations of these differences were then calculated to compare these measurements with the inverse square law theory. Some measurements were also made in the near field, and closer than one-quarter wavelength from the wedge tips. The average of the means from 12–74 in. was 0.73 dB below theory. The average 95% confidence limits of these data in this range was +/− 1.1 dB. These deviations compare favorably with the acceptance criteria in the ANSI standard. The near/far field guideline also appears to be reasonable. Measurements closer than one-quarter wavelength from the wedge tips may be possible. However, further extremes characterization is needed. Envelope noise reduction should also be measured.

In 1962, Cavanaugh, et al., published the results of research which lead to a single number rating system for speech privacy of walls referred to as the N number [‘‘Speech Privacy in Buildings,’’ J. Acoust. Soc. Am. 34, 475–492 (1962)]. The N number is derived from measured one-third octave band transmission loss data weighted using factors signifying the relative contribution to the articulation index. When the N number is summed with factors for source room floor area, source room speech use, measured adjacent room background noise rating, and the privacy requirement, the N number correlated subjective reactions observed in case studies better than average wall transmission loss alone. Owens Corning, the sponsor of this research, published the N number along with sound transmission class (STC) for several years. With the emergence of regulation of speech privacy in health care facilities, the Health Insurance Portability and Accountability Act (HIPAA), it seemed reasonable to revisit the N number. This paper will review the N number methodology and compare some building partition STCs and N numbers, with special attention on the impact of cavity insulation.

ASTM C 423 specifies the industry accepted standard method to measure sound absorption coefficients by the reverberation room method. These coefficients are sometimes referred to as Sabin absorption coefficients. Because of the finite size of the sample used in these measurements, diffraction effects usually cause the apparent area of a specimen to be greater than the geometric area, thereby increasing the coefficients measured by this method over a sample of infinite lateral dimension which can be analyzed theoretically. In this paper, an empirically derived equation is present that transforms predicted absorption for large (infinite) flat absorbers to that which is measured by the reverberation room method. This empirically derived equation is based on an extensive database of measured absorption coefficients for A-mounted fiberglass materials with a wide range of flow resistivities and thickness. Estimated absorption is compared with measured data and infinite sample size predictions based on Mechel design charts [J. Acoust. Soc. Am. 83, 1002 (1988)]. Comparisons are also made between the estimate made with this empirical method, and an analytical method, which accounts for diffraction developed by Northwood [J. Acoust. Soc. Am. 31, 595 (1959); 35, 1173 (1963)].