Speech transmitting glass window - has sloping separated armoured glass parts with speech transmitting slots

摘要

The speech transmitting slots become arrower progressively from the wall outside face towards the wall inner face. The speeck slots are formed by separated superposed plates which are inclined inwards and upwards. In an alternative version the plates are ground on opposite faces at different angles to form converging speech transmission slots (13). The speech transmission partition wall is made from armoured glass and it is used for the service windows in banks and public offices. This window has several speech transmitting slots. The acoustic damping is greatly reduced. Glass fragments are not readily produced on firing through the slot.