Page 5
Fundamental Frequency & Harmonics
Below is a frequency scan of a piezoelectric audible alarm that has a resonant frequency
of 2,800 Hz. As you can see, there is a strong frequency peak at 2.8 kHz and several
smaller frequency peaks that follow called harmonic frequencies. The table below the
chart shows that the size of the harmonic frequencies are significantly smaller than the
fundamental frequency for this particular alarm unit. Because this alarm has a large
fundamental frequency and much smaller harmonic frequencies, the sound quality of this
part will be very good. When this alarm is activated, the listener will hear one clear
frequency (also called sound pitch) from the alarm. Other electronic alarm technologies
such as electro-magnetic or electro-mechanical type alarms often have much larger
harmonic frequency components resulting in less clear tone.
