In the present experiment the question was examined, whether identical noise situations perceived under different attentional instructions lead to different loudness judgments. Therefore within the sound of an engine with varying sound pressure level, the signal of a telephone was hidden (signal-to-noise-ratio -20.5 dB). Under three attentional conditions 14 subjects had to listen to the sound of the engine either casual, attending to the level peaks, or attending to the hidden telephone signal. Before and after the presentation of the engine sounds psychometric loudness-functions were measured by a category partitioning procedure. As an indicator for the sensory sensitivity under non-threshold conditions, the adaptation-level was determined. The results of the experiment showed that the adaptation-level is shifted by attentional instructions. Depending on the attentional focus, the loudness impression can be modified in such a way as if the sounds were presented with a different sound pressure level up to 3 dB (A). The results are discussed in the frame of psychological theories of attention and theories of information integration.