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Acoustics in Signalling Technology

Basic parameters of acoustics

Sound is the propagation of pressure fluctuations (also known as sound waves) in an elastic medium. Humans can perceive a limited range of sound waves, known as the audible spectrum.

Sound Frequency - hertz (Hz)

Sound frequency is measured in hertz (Hz) and refers to the number of vibrations per second of a sound. It determines the pitch of a sound and influences how high or low a sound is perceived. The audible frequency range for humans is generally between around 20 Hz and 20,000 Hz. The upper frequency limit decreases with increasing age. At the age of 50, the limit is still around 12,000 Hz on average, but at an older age it is often only 5,000 Hz. For this reason, acoustic signalling devices usually operate in a frequency range between 500 Hz and 5000 Hz.

Sound pressure - decibels (db)

Sound pressure level is measured in decibels (db) and is an important measurement that indicates the level or strength of a sound signal. The sound pressure level is often used to measure and evaluate the noise level or loudness of sound sources. As the sound pressure level is logarithmically scaled, an increase of 10 dB means a doubling of the perceived loudness. For example, a sound pressure level of 70 dB is twice as loud as a sound pressure level of 60 dB.