There are three main requirements for the alarm sound. First, the fundamental frequency must be between 150Hz and 1kHz. Second, there must be at least four harmonic peaks between 300Hz and 4kHz. Third, the sound level of the harmonic peaks must be within ± 15dB of the fundamental frequency. The graph shows the frequency response of one of Mallory’s IEC60601-1-8 compliant buzzers. On the vertical scale is the sound pressure level and on the horizontal scale is the frequency. As the graph shows, the sound frequency of this buzzer has many different frequency components so the resulting sound that is actually heard is a blended sound. A familiar analogy would be the sound caused by hitting many keys on the piano at one time. A more detailed review of the individual requirements follows in the next series of slides.