Views: 50 Author: Site Editor Publish Time: 2019-08-24 Origin: Site
Sound is a vibration of air
Sounder pressure level (dB) = loudness of sound
Air pressure is called Sound Pressure when a sound is propagated through the air.
Minimal loudness of sound perceived by a human is defined as 0dB (20μPa). Sound pressure that Manorshi’s sound component produces is approximately 70 to 90dB （measured in 10cm distance).
The more distant the receiver is from the sound source, the lower the sound gets.
"Specification of Sound Pressure Level "→ The necessary information are the distance from the sound source and how loud the sound should be there.
Frequency (Hz) = pitch of sound
The number of times of the dilatational wave of air per second is frequency.
In general, man’s audible frequency range is about 20 Hz to 20 kHz.
Especially, the frequency range of 2 kHz to 4 kHz is the most audible.
For this reason, most of the piezoelectric sound components are used in this frequency range.
*It is slightly hard for older persons to hear the frequency range of over 3 kHz.
Buzzers are commonly used as piezo buzzers and magnetic buzzers. Compared to piezo buzzers (12~220 V, <20 mA), the magnetic buzzer operates at lower voltages and higher currents (1.5 to 12 V, > 20 mA). Piezo buzzers typically have a greater maximum sound pressure level (SPL) than magnetic buzzers.In a magnetic buzzer, a current is driven through a coil of wire which produces a magnetic field. A flexible ferromagnetic disk is attracted to the coil when the current is present and returns to a "rest" position when the current is not flowing through the coil. The sound from a magnetic buzzer is produced by the movement of the ferromagnetic disk in a similar manner to how the cone in a speaker produces sound. A magnetic buzzer is a current driven device, but the power source is typically a voltage. The current through the coil is determined by the applied voltage and the impedance of the coil.