As a telephone operator you are unable to project your voice at the normal conversational level because of static
and transmission line interference. The average power furnished by the lungs to project your voice as loudly as possible is
The fundamental frequency range scale shown in figure 6 is the type of reference scale used by the telephone
engineers when designing and constructing telephone lines and equipment. The most important factors affecting the
design and construction of the telephone equipment is the:
power concentration of the normal singing voice and the operator's ability to distinguish between the
complete fundamental frequency range and the harmonic frequency range.
frequency range of the voice and the equipment's ability to respond to the difference in power delivered by
frequency range of the overtones and the equipment's ability to respond to the difference in power delivered
by the fundamental frequency.
power concentration of the overtone singing voice and the operator's ability to distinguish between the over
tone frequency range and the harmonic frequency range.
The thresholds of audibility and feeling vary according to the frequency of the sound. The range of frequencies to
which the average ear is most sensitive is:
50 - 500 hertz.
150 - 2,000 hertz.