Audible signalling systems, e.g. audible personal calling systems

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Whistling kettles In model railways, arrangements for imitating locomotive features, e.g. whistling, signalling, puffing Road surface markings specially adapted for audible or vibrational signalling Acoustical signalling devices on ladders characterised by being mounted on undercarriages or vehicles Indicating the time by acoustic means Producing acoustic time signals by electrical means Telephonic communication systems combined with bell systems