Average long term speech spectrum (talking over one minute). The maximum energy is in the 250Hz and the 500Hz band. These lower-frequency bands correspond to vowel sounds, the higher-frequency bands in the 2k and 4k region correspond to consonant sounds.
Vowels carry the power of the voice and consonants provide intelligibility. But each range alone can not provide the full intelligibility.
single Band
provided Intelligibility
250Hz
very poor
500Hz
about 12%
2kHz and 4kHz
together about 57%
measurement print of male human voice
about 15 seconds of typical speech
Relationship between the distance of two
Persons talking and the receiving speech level, normal talking:
