Testing an audio system. The thresholds of loudness and high frequency are being tested by projecting progressive plane sound waves at a listener. Progressive plane waves travel from one location to another as a series of parallel waves,allowing some sounds to be clearly heard from a distance. Photographed at the National Physical Laboratory,Teddington,UK,in 1954 | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / NATIONAL PHYSICAL LABORATORY (c) CROWN COPYRIGHT |
Bildgröße: | 4992 px × 3543 px |
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Eigentums-Rechte: | nicht erforderlich |
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