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The sound environment in hospitals is complex. While there have been several studies that address the acoustic environment in hospitals, there is a limited amount of research done concerning the effect that noise has on staff. This thesis describes two related studies: 1) analysis of the relationships between acoustics and perceptual staff outcomes using an existing data set collected in real hospitals; 2) development of methodologies to test the relationships between acoustics and hospital staff task performance in a simulated laboratory setting. In the first study it was found that mental health and perception of noisiness were occupational factors that were related to the sound environment using a variety of acoustic metrics. Only a few acoustic metrics were shown to be statistically significant related to dependent variables in a direct correlation (e.g., as the acoustic conditions worsened the dependent variable also decreased). However, almost all acoustic metrics tested had a statistically significant relationship with mental health once subjective job strain was considered as a moderating factor. This means that while the direct impact of sound may not be immediately observable, sound may play a more significant role once subjective job strain is taken into account. In the second study, a new methodology was developed to directly relate staff task performance to noise and beta-tested on a single group of subjects. The methodology development included synthesizing a signal that was acoustically comparable to those heard in real hospitals in order to simulate a realistic noise exposure in a controlled environment. Additionally, objective methods of measuring performance and perception were devised by utilizing task performance scripts already validated in other studies and developing new surveys that could be administered to subjects to garner their perceived task performance and perceptions of the simulation room environment, including noise.

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Laboratory measurements of three predicted wave types (two compressional or P-waves and one shear S-wave) have been made in artificial soils. The Type-I P and S-wave are predicted to be most sensitive to the macroscopic elastic properties of the frame, whilst the Type II P-wave is predicted to be most sensitive to the hydrodynamic material properties. A loudspeaker source has been used for the preferential excitation of the Type II P-wave whilst preferential excitement of the Type-I P-wave has been accomplished using a mechanical shaker. Probe microphone measurements of the Type-II wave allowed the flow resistivity and tortuosity of the material to be determined using a rigid frame model, whilst deduction of elastic moduli has been made from signals received at buried geophones. It has been shown that microphone signals include Type-I P-wave energy in a high flow resistivity soil. Acoustically deduced soil properties are consistent with mechanically derived values. A systematic investigation of outdoor measurements of acoustic-to-seismic coupling ratio has been made. From the measurements, it has been found that the geophone-ground coupling has a great effect upon the measured coupling ratio. In-situ calibration methods have been developed to overcome this problem. whilst the novel use of a Laser Doppler Vibrometer has been proposed to provide a completely non-invasive method of measuring motion in soils. The measured coupling ratio has been compared with theoretical predictions, using a modified Bio-Sto11 formulation. The model can be used to predict values of flow resistivity, porosity, bulk and shear moduli and layer depths. Reasonable agreement has been obtained between the model and data. Procedures that exploit acoustic-to-seismic coupling data and models to determine soil properties have been developed and used to measure the soil properties of friable agricultural soils where more standard investigation techniques have proved unsuitable.

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