Auditory signals are signals expressed by the intensity, frequency and length of sounds made by different musical instruments. If you use a horn, whistle, the sound from the dock and the signals from locomotives and rail cars, they are all auditory signals.

Railway signal is the abbreviation of railway signal system or equipment. The technical equipment on the railway to ensure the safety of shunting operation, improve the passing capacity of stations and sections and the ability of train disintegration, and improve the working conditions of operators. According to different technical means, railway signals can be divided into visual signals and auditory signals. It can also be subdivided into daytime signal, night signal, day and night general signal, fixed signal, mobile signal, ground signal, locomotive signal and manual signal.

Extended data:

Classification of railway signals:

1. The sensory reception of railway signals can be divided into visual signals and auditory signals.

2. Railway signals are divided into daytime signals, night signals and day-and-night general signals according to the use time.

The use time of daytime signal is from sunrise to sunset, and the use time of night signal is from sunset to sunrise. In case of fog, storm and snow during the day or night, when the daytime signal can't reach the specified display distance, the night signal should be used. The light in the tunnel is dark, and the daytime signal is not easy to see, so only the general signal at night or day and night is used in the tunnel.

3. According to the setting mode, railway signals can be divided into fixed signals and mobile signals.

The position of fixed signal is fixed, such as signal, signal, etc. With the change of job site or workers' position, the position of signal display will also change, such as hand signal flag (light), temporary protection signal, torch, etc.

Baidu Encyclopedia-Railway Signal