A fire alarm system, comprising: a control panel, arranged to control one or more devices on an addressable fire alarm loop; one or more detector devices, arranged to send an alarm condition signal to the control panel upon detection of an alarm condition; one or more notification devices arranged to receive an alarm output signal from the control panel; and a plurality of voice alarm devices, wherein the plurality of voice alarm devices are separate devices from the one or more detector or notification devices, and are arranged to output an audible alarm voice message upon receipt of an alarm output signal from the control panel, the voice alarm devices comprising: a loop connection interface for retroactively fitting the voice alarm devices to the fire alarm loop, arranged to connect the voice alarm device to the fire alarm loop; a processor, arranged to process signals received via the fire alarm loop; at least one memory, arranged to store one or more audio files; and a speaker, arranged to output a selected audio file from the one or more audio files in the event of an alarm condition, wherein the alarm output signal from the control panel comprises timing information, defining a point in time at which the selected audio file of the one or more audio files should be output by each of the plurality of voice alarm devices to synchronise the audio; and wherein the processors of the voice alarm devices are configured to process the timing information so that voice alarm devices in close proximity to each other have synchronised audio, therefore preventing individual voice alarm devices from obscuring each other's output audio signal. a control panel, arranged to control one or more devices on an addressable fire alarm loop; one or more detector devices, arranged to send an alarm condition signal to the control panel upon detection of an alarm condition; one or more notification devices arranged to receive an alarm output signal from the control panel; and a plurality of voice alarm devices, wherein the plurality of voice alarm devices are separate devices from the one or more detector or notification devices, and are arranged to output an audible alarm voice message upon receipt of an alarm output signal from the control panel, the voice alarm devices comprising: a loop connection interface for retroactively fitting the voice alarm devices to the fire alarm loop, arranged to connect the voice alarm device to the fire alarm loop; a processor, arranged to process signals received via the fire alarm loop; at least one memory, arranged to store one or more audio files; and a speaker, arranged to output a selected audio file from the one or more audio files in the event of an alarm condition, a loop connection interface for retroactively fitting the voice alarm devices to the fire alarm loop, arranged to connect the voice alarm device to the fire alarm loop; a processor, arranged to process signals received via the fire alarm loop; at least one memory, arranged to store one or more audio files; and a speaker, arranged to output a selected audio file from the one or more audio files in the event of an alarm condition, wherein the alarm output signal from the control panel comprises timing information, defining a point in time at which the selected audio file of the one or more audio files should be output by each of the plurality of voice alarm devices to synchronise the audio; and wherein the processors of the voice alarm devices are configured to process the timing information so that voice alarm devices in close proximity to each other have synchronised audio, therefore preventing individual voice alarm devices from obscuring each other's output audio signal.