Abstract: To produce a signal simulating the characteristics of the average human voice, a basic periodic waveform with generally sinusoidal sections separated by level sections is passed through a first filter for substantially equalizing its frequency components and is then shaped in a second filter whose transfer function approximates that of the vocal tract in a frequency band of 0 to 4 kHz. The basic waveform fed to the first filter may be modulated in amplitude and/or recurrence period by a pseudorandom signal from an ancillary generator.

Abstract: A device to be used in phonometric measurements on telephone equipment, simulating a human ear, has a generally disk-shaped body with an annular ridge encompassing a frustoconical central recess serving as a wide-open entrance cavity. The body has several internal cavities communicating with the recess through restricted channels, namely a pair of major cavities resonant at low audio frequencies, an intermediate cavity resonant in the middle audio range, and a minor cavity resonant at high audio frequencies, the last-mentioned cavity having the shape of a narrow cylinder extending generally along the body axis. A microphone, connected to a measuring circuit, rises from the bottom of the recess to substantially the top level of the surrounding ridge to pick up incoming sounds at that level.