TECHNICAL NOTES AND

RESEARCH BRIEFS R. H. Nichols, Jr. Bell Telephone Laboratories, Inc., Whippany, New Jersey 07981

AUDIOMETRIC SCREENING OF THE NEWBORN

Wayne Rudmose Tracor, Inc., Austin, Texas

DURING THE PAST FEW YEARS, CONSIDERA- ble attention has been given by otologists and audiologists to the problem of testing the hearing of the newborn child before he leaves the hospital of his birth. Research has shown that if a child with a severe hear-

ing loss is identified at an early age, and if proper steps are taken, the child may learn to speak in a most acceptable fashion. If the hearing deficiency is not identified, or if proper steps are not taken before the child is approximately two years old, then the child's speech almost inevitably bears the scar of the deaf. Although the incidence of a severe hearing loss at birth is probably of the order of one in a thousand, the value of discovering the infant with a hearing handi- cap is beyond estimation.

TR^COR has followed the scientific work

in this particular field for many years and has recently developed the Warblet© 3000 (shown in Fig. 1) to satisfy the needs of people who have set up screening programs in the maternity wards of hospitals.

It is generally accepted that the critical frequency range for screening the hearing of the neonate is centered around 3000 Hz.

For this frequency, the sound-pressure level (SPL) required to produce a visible and repeatable reaction from a newborn with normal hearing is on the order of 80-90 dB. The Warblet produces a 3000-Hz signal that is frequency modulated at a rate of approximately 30 Hz with a deviation of approximately 150 Hz. The instrument is calibrated to produce SPL's of 80, 90, or 100 dB at 10 in. from the bell of the horn.

The unit is light weight, solid state, and is normally hand held by a pistol-type grip, as can be seen in the photograph (Fig. 1). A switch in the handle activates the signal, and an output meter monitors the voltage on the voice coil of the folded horn. Battery life is in excess of three months of normal operation in a nursery.

868 Volume 41 Number 4 1967

Typical screening programs are carrietl out by volunteer workers. Two volunteers work as a team and score their observations

independently. The newborn is tested in his crib by simply pointing the Warblet at his head and maintaining a distance of approxi- mately 10 in. between the head and the bell of the loudspeaker. A 2- or 3-sec burst of the Warbler tone is presented, and the ob- servers carefully watch for some type of definable movement which they feel is asso- ciated with the acoustic stimulus. Each ob-

server independently ranks the strength of the infant's reaction on a scale of 1 to 5, with 1 representing essentially no observa- ble response and 5 a vigorous response. Infants failing to respond are retested several times, and if the failure is consistent. the medical record of the child is stamped

DON'T BURY cps YET!

W. Dixon Ward

ltearing Research Laboratory, University of Minnesota, Minneapolis, Minn. 55455

Retention oJ "cps" or "c/s" is urged in those cases involving "cycles" oJ tone bursts.

ALAS, 'TIS AS I FEARED. DURING THE IN- terim between submission and publication of my earlier Letter (Ward, 1966) defend- ing my friend "kc," both he and his cousin "cps" have been grievously stricken by their foes. Indeed, "kc" seems to be as completely defunct as his great-uncle "double vibra- tions," and there is apparently little that we can do to resuscitate him.

However, let me plead for emergency treatment for "cps": amputate his arms and legs, if you must, but let him live on in at least one form. Suppose we have a Hertzor (previously known as an oscillator) that is set at 1000. Its signal is sent to an electronic switch that delivers to an ear-

phone 100-msec pulses of tone separated by 100 msec. The voltage from the Hertzor

Fig. 1 The Warbler; a device for assess- ing hearing of newborn.

"not cleared for hearing." The pediatrician is then advised of the findings and normally will watch the progress of the child for any signs of a hearing deficiency. •-•

varies sinsuoidally 1000 times each second; this is properly called a 1000-Hz tone. But what of the repetition rate? In any second, there will be five tone bursts--must we then

say that the repetition rate is "5 Hz" [don't laugh--it has already happened (Dallos and Tillman, 1966)• so that the stimulus is "5-Hz 1000-Hz tone pips with 50% duty cycle"? I hope not.

There are, that is, several kinds of "cycles," so I strongly urge us not to use Hz every time we would have used "cycles per second," but only when the cycles in- volve vibrations of the sort one gets from a Hertzor, retaining either cps or c/s for other types of cyclicity. If we do so, then the change, instead of being an unnecessary, capricious, and arbitrary step, will have some actual benefit toward clarity in communication?-•

DALLOS, P. J., AND TILLMAN, T. W. (1966) "The Effects of Parameter Variations in B•.k•sy Audiomerry in a Patient with Acoustic Neu- rinoma," J. Speech Hearing Res. 9, 557-572; for example, their Table 4 and Fig. 9.

\VARD, W. D. (1966) "Why Strike Out the Xlighty kc?" J. Acoust. Soc. Am. 3•) 978-979.

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