In electronic sounders, the signal tone is generated electronically by a microprocessor, amplified and emitted via a loudspeaker. What types of audible signaling devices exist?Īt Auer Signal we distinguish between electronic and electromechanical sounders: The gong plays three different sounds and then repeats again. The alarm tone is a pulsating tone, with a very high pulse-to-pause ratio. After the pause, the tone is again slightly higher and then becomes lower again. The falling tone becomes lower over time, followed by a short pause. The slowly rising tone gradually becomes higher as it progresses, and then remains unchanged at the highest note. After the pause, the tone is again slightly lower and then becomes higher again. The rising tone becomes higher over time, followed by a short pause. The alternating tone plays alternating higher and lower tones. The most important types of signal tones are explained in the table below: TonalityĪ continuous tone is a constant tone that does not change its pitch.Ī pulsating tone is a continuous tone with short, periodic pauses. The ASX multi-tone siren can play 63 types of tone. The acoustic signaling devices from Auer Signal have a variety of different signal tones. The different signal sounds have different ranges depending on the type of sounder, signal type and volume setting: USAGE AND VOLUME OF VARIOUS TYPES OF ALARMS The higher the amplitude, the louder the sound. The amplitude is the size of an oscillation that emanates from a sound. The volume of a sound perceived by the human ear depends on the amplitude of the vibrations. Waves of different wavelengths can have the same frequency. Comparing two waves of different wavelengths, a higher frequency doesn't always indicate faster movement, although it can. Hz = number of uninterrupted cycles per secondĬomparing two waves of the same wavelength, a higher frequency is associated with faster movement. It is measured in Hertz (abbreviated Hz). The number of times per second that a soundwave repeats itself is called frequency. If the frequency of a sound is below 20 Hertz, that sound is then called “infrasound”. Depending on the age and functionality of the hearing, the lowest perceived sounds (hearing threshold) can be at 16 Hz, the highest at 20000 Hz. High-pitched tones are at a frequency of 2000 Hz to 5000 Hz. Low pitched sounds range between 50 Hz and 100 Hz for the human ear. The higher the frequency of the vibrations, the higher the sound. Whether we hear a high- or low-pitched sound depends on the number of vibrations per second (frequency). A noise, on the other hand, consists of uneven vibrations and frequencies. A sound is composed of several tones that sound simultaneously and overlap. The speed of sound in air is about 340 meters per second.Ĭompared to a sound, a bang, for example, is a short and strong vibration. In airless spaces, for example in a vacuum and also in outer space, sounds can be produced, but the sound does not propagate. In an audible signaling device, for example, a membrane vibrates, causing air to move and sound. Sound waves are longitudinal waves, which means that the vertical orientation of the particles does not change. If air starts to move, this is called a surge wave and sounds are created. What is sound and how is it created?Ī sound is an even, consistent vibration of the air (another medium can also be water or metal) that is perceived by the ear of the listener. Audible alarms are, for example, used in fire alarm systems or security systems. Those dangers could be trucks backing up or gates closing.Īudible alarms can be generated by audible signaling devices, but also by instruments or people. Mostly, audible alarms serve to warn of imminent dangers in areas where visual indications cannot be used sufficiently to alert people. */ # include "pitches.Audible alarms produce loud noises and are used to draw attention to an upcoming action. * Melody Plays a melody circuit: - 8 ohm speaker on digital pin 8 created modified by Tom Igoe This example code is in the public domain.
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