A multi-sensor detector comprising: at least one fire sensor; at least one audio transducer for converting an incident acoustic signal to an electrical signal; control circuits coupled to the at least one fire sensor and the electrical signal; and an interface for communication with a displaced monitoring system; wherein: the detector further comprises a thermal sensor coupled to the control circuits; the control circuits are configured to establish the presence of a fire condition in the vicinity of the audio transducer based at least in part on incident acoustic signals emitted by a fire present in a predetermined local region adjacent to the audio transducer; and the control circuits are configured to enter a heightened sensing mode from a normal sensing mode in response to a first one of the audio transducer, the fire sensor or the thermal sensor first sensing an alarm condition, by increasing the sensitivity of the other sensors, wherein: if in the heightened sensing mode a second one of the audio transducer, the fire sensor or the thermal sensor senses an alarm condition within a set time period after the first one has sensed an alarm condition, the control circuits are configured to trigger a fire alarm and notify a displaced monitoring system, and if in the heightened sensing mode, a second one of the audio transducer, the fire sensor or the thermal sensor does not sense an alarm condition within the set time period, the control circuits are configured to revert to the normal sensing mode. at least one fire sensor; at least one audio transducer for converting an incident acoustic signal to an electrical signal; control circuits coupled to the at least one fire sensor and the electrical signal; and an interface for communication with a displaced monitoring system; wherein: the detector further comprises a thermal sensor coupled to the control circuits; the control circuits are configured to establish the presence of a fire condition in the vicinity of the audio transducer based at least in part on incident acoustic signals emitted by a fire present in a predetermined local region adjacent to the audio transducer; and the control circuits are configured to enter a heightened sensing mode from a normal sensing mode in response to a first one of the audio transducer, the fire sensor or the thermal sensor first sensing an alarm condition, by increasing the sensitivity of the other sensors, wherein: if in the heightened sensing mode a second one of the audio transducer, the fire sensor or the thermal sensor senses an alarm condition within a set time period after the first one has sensed an alarm condition, the control circuits are configured to trigger a fire alarm and notify a displaced monitoring system, and if in the heightened sensing mode, a second one of the audio transducer, the fire sensor or the thermal sensor does not sense an alarm condition within the set time period, the control circuits are configured to revert to the normal sensing mode. the detector further comprises a thermal sensor coupled to the control circuits; the control circuits are configured to establish the presence of a fire condition in the vicinity of the audio transducer based at least in part on incident acoustic signals emitted by a fire present in a predetermined local region adjacent to the audio transducer; and the control circuits are configured to enter a heightened sensing mode from a normal sensing mode in response to a first one of the audio transducer, the fire sensor or the thermal sensor first sensing an alarm condition, by increasing the sensitivity of the other sensors, wherein: if in the heightened sensing mode a second one of the audio transducer, the fire sensor or the thermal sensor senses an alarm condition within a set time period after the first one has sensed an alarm condition, the control circuits are configured to trigger a fire alarm and notify a displaced monitoring system, and if in the heightened sensing mode, a second one of the audio transducer, the fire sensor or the thermal sensor does not sense an alarm condition within the set time period, the control circuits are configured to revert to the normal sensing mode.