To simplify and facilitate a detection system of a siren or a warning signal.

An emergency vehicle alert system for detecting a signal of a selected voice frequency emitted by a warning device of a vehicle is connected to a warning indicator and includes a detector which is connected to a plurality of operational amplifiers and detects a signal spectrum of the selected voice frequency. The plurality of operational amplifiers includes a first operational amplifier for detecting a low-frequency signal spectrum within around 50 feet from a warning device sound source; a second operational amplifier for detecting a low-frequency signal of a signal spectrum of the selected voice frequency within around 1,500 feet from the warning device sound source; a third operational amplifier for detecting a high-frequency signal of the signal spectrum of the selected voice frequency within around 50 feet from the warning device sound source; and a fourth operational amplifier for detecting the high-frequency signal of the selected voice frequency signal spectrum with within around 1,500 feet from the warning device sound source.