| Popis: |
A phenomenon which affects the transmission of sound in air at reduced ambient pressures is the dependency of microphone and loudspeaker characteristics on the ambient pressure. The sensitivity of a transducer operated as a microphone usually increases as the pressure is reduced. It follows then, by the reciprocity theorem, that the sound pressure produced at a point in space by a transducer operated as a loudspeaker does not vary directly as the ambient pressure. The frequency response is affected as well. For example, where the mechanical damping of a transducer diaphragm is provided principally by the radiation loading at atmospheric pressure, the sensitivity at the resonant frequency becomes enormous at low pressures. This results in a deterioration of the transient response which is of importance when the transducer is pulsed. Photographs of the response of a high‐quality condenser microphone to pulses will be shown at various ambient pressures to illustrate the effect. Some general relations will be... |
