engleski

Examination of Required Signal-to-Noise Margin in Laboratory Subjective Evaluation of Sound Insulation

In subjective testing of sound insulation, the most important demand is to reproduce the test signals, i.e. the ones that would be observed in a receiving space, with correct absolute level and spectrum. If the levels of typical source sounds such as speech, music, traffic noise or living noise in general are kept at realistic values, the levels of test signals are low and can often be comparable to the level of background noise present in the laboratory. The task set in this research is to determine the signal-to-noise margin required for nullifying the disturbing influence of background noise during listening tests. Therefore, a series of listening tests was made, in which the hypothetical test signals were presented to the listeners together with background noise. The listeners were asked to adjust the level of the test signal so that the background noise no longer represents a disturbance, i.e. cannot be heard. The test signals and background noise were obtained by filtering typical source sounds with low-pass filters, roughly simulating their transmission through walls or other building elements. Additionally, a sample of background noise that is present in a specific laboratory room was taken and also used in the tests as a background noise sound. The results of the listening tests were statistically analyzed. Based on the resulting data, the sounds were then analyzed in an objective manner as well. The obtained values of typical objective parameters were brought into relationship with the results of subjective investigations.

sound insulation; subjective evaluation; background noise; signal-to-noise margin

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