The avian and mammalian tectorial membranes both contain two non-collagenous glycoproteins, a- and ß-tectorin. To determine whether variations in the primary sequence of the chick and mouse a-tectorins account for differences in subunit composition and matrix structure of the tectorial membranes in these two species, the cDNA for chick atectorin was cloned and sequenced. The derived amino acid sequence was found to have 73% identity with mouse a-tectorin, suggesting that the tectorins are highly conserved proteins. The central region of chick a-tectorin contains fewer potential N-glycosylation sites than that of mouse a-tectorin and is cleaved at two additional sites. The extra glycosylation sites in the mouse sequence may help occlude sites of proteolytic attack. In situ hybridisation and northern blot analysis indicate that the spatial and temporal patterns of chick a- and ß-tectorin mRNA expression in the inner ear are different, suggesting that the two tectorins may each form homomeric filaments. Early functional recovery in the chicken after sound damage has been attributed to the rapid regeneration of the tectorial membrane. In situ hybridisation indicates that both aand ß-tectorin mRNAs are upregulated in the sound damaged basilar papilla. The regenerated tectorial membrane contains both a and ß-tectorin proteins. In order to understand how the tectorin genes are regulated during development and regeneration, the upstream non-coding region of the ß-tectorin genes from mouse and chicken were compared in an attempt to identify potential regulatory elements. DNA sequence alignments of the chick and mouse ß-tectorin upstream sequence show low identity, suggesting that the chick and mouse ß-tectorin promoters have not remained functionally conserved throughout evolution.

This thesis presents investigations on the potential negative effects of wind turbine noise on the human ear from a sound point source (i.e. wind farm). In Chapter 2, the tectorial membrane, which is a crucial gelatinous structural matrix located within the cochlea of the inner ear, is considered to have a similar constitutive stress-strain relationship to that of an elastomer (rubber) in tension. The tectorial membrane appears to stretch when subjected to constant heavy sound stimulation. The tectorial membrane is modeled as a simply-supported beam with an external load Pext applied at midspan. A virtual work approach is used to balance the external work at midspan Pextδz of the tectorial membrane with the internal strain energy from its hysteresis loops. These hysteresis loops quantify the amount of damage that the tectorial membrane undergoes due to an applied external loading. Normalized damage tables are presented at the end of the chapter to suggest safe distances away from the wind turbines to limit damage to the tectorial membrane. Chapter 3 considers a hypothetical autonomous village constructed in South Pretoria, South Africa. This village accommodates approximately 2000 people (~500 families) and receives electricity for hot water from a nearby 2.5 MW wind farm. The design process for the village is discussed from an architectural and design standpoint. The wind farm specifications, specifically the number of 2.5 MW wind turbines needed to provide electricity for hot water, are established. Results from Chapter 2 are used to suggest minimum safe distances between the wind farm and the autonomous village in the context of limiting damage to the tectorial membrane.