| Es ist nachzuprüfen, ob innerhalb einer Halbkugel von mindestens 5 m Radius bis zu der zu messenden Höchstfrequenz, insbesondere in Messrichtung und in Höhe der zu prüfenden Vorrichtung und des Mikrofons, die sphärische Abweichung 1 dB genau eingehalten… |
Alternatively, it may be tested in a semi-anechoic chamber or in an open space [5]. In this case, precautions shall be taken to avoid reflections from the ground within the measuring area (for instance by erecting a set of absorbing screens). Compliance with the spherical divergence to a limit of 1 dB within a hemisphere of not less than 5 m radius, up to the maximum frequency to be measured, especially in the measuring direction and at the height of the apparatus and the microphone, shall be… |
