Deaf Will Be Helped Toward Normal Speech by Hunt's Apparatus That Measures Voice Pitch

A further valuable aid to the deaf, an apparatus which will help teach them to speak with normal intonation, has been designed at the Cruft Laboratory by Frederick V. Hunt, instructor in Physics and Communication Engineering.

The new apparatus is a refinement of instruments already in use for measuring the frequency or "pitch" of sounds. These older instruments have the disadvantage that they are not sensitive enough to catch the quick transitions in speech, often lasting for only a fiftieth of a second, which this new apparatus is easily capable of recording.

The other great disadvantage of the old instruments is that the presence of strong overtones might completely obscure the fundamental frequency which the ear catches as the "pitch" of the voice.

The deaf person wants to regulate the fundamental tone of his speaking voice. He can only do this by regulating the "pitch." The new machine, by employing a distorting amplifier and a sound filter, can segregate and record the fundamental pitch even when it is so obscure in the original speech as to be hardly detectable by the usual instruments.

In using the machine, the deaf person talks into a microphone and the sounds of his voice are changed into electrical energy. This energy is then converted into impulses which can be measured in terms of "pitch."

The deaf person can watch the fluctuations of his voice indicated by the pointer of the instrument which registers the impulses immediately. Frequencies from zero to 16,000 cycles per second can be recorded, while the range of the human ear is from 20 cycles up to a high squeak of about 16,000 cycles per second.

When operated in special electrical hookups the apparatus can also be used to record directly the vibration frequencies of rotating machinery or for monitoring the frequency of broadcasting stations. The apparatus registers not only the fundamental pitch of the voice but also of notes played on musical instruments.