  We present measurements of thermal noise in niobium and aluminium flexures.
Our measurements cover the audio frequency band from 10Hz to 10kHz, which is of
particular relevance to ground-based interferometric gravitational wave
detectors, and span up to an order of magnitude above and below the fundamental
flexure resonances at 50Hz - 300Hz. Our results are well-explained by a simple
model in which both structural and thermoelastic loss play a role. The ability
of such a model to explain this interplay is important for investigations of
quantum-radiation-pressure noise and the standard quantum limit.
