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High levels of noise have been found to cause offline events and data loss in information technology equipment in multiple data centers. Studies by this author and others showed these events were a result interaction between rotational storage media or hard drives (HDD) and air-borne noise. In particular, noise with a great degree of tonal content posed the greatest threat to HDD performance. A series of tests has been performed to understand this noise-HDD interaction. A test fixture was built and HDDs were exposed to sinusoidal signatures from 1000 Hz to 16 kHz. The incident sound pressure was monitored to capture the sensitivity of the HDDs at multiple sound pressure levels. Sound pressure, frequency and HDD performance were all correlated along with known HDD manufacturer provided vibratory sensitivities. Each subsequent generation of HDD showed greater incidence of tonal sensitivities and lower sound pressure level needed to achieve such high levels of performance degradation. Given the correlation with the vibratory sensitivities, the tonal response seems to be unique to the design and manufacture of each HDD individually.

A low frequency noise study was conducted at the Pennsylvania State University to investigate human response to the low frequency content of aviation noise. Metric assessment included level based and loudness metrics, including time-varying loudness. Current predictive noise models and metrics may underestimate the impact of low-frequency noise produced by aviation noise. Assessing the role of low frequency noise on human response will facilitate understanding how this type of noise can impact communities. Indoor recordings of aircraft arrivals and departures at Washington Dulles International Airport made in 2004 were used to assess subjective noise annoyance. These recordings and low-frequency variants of these recordings were reproduced for subjects through the Gulfstream Supersonic Acoustic Signature Simulator II (SASS II); the signatures were then rated for annoyance. Subjective judgments were statistically analyzed and compared against objective metrics that were calculated for each signature. Results are shown that all things being equal higher levels of low-frequency content in aircraft noise can result in increased annoyance in subjects. The C-weighted sound exposure level was found to correlate well with the subjective annoyance response.

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