Prototype high-speed tape target transport for a laser plasma soft-x-ray projection lithography source.

A prototype high-speed tape target transport is constructed for use in a high-repetition-rate laser plasma source. To reduce plasma debris, a 1000-5000-A-thick film of target material is supported by thin Mylar tape backing. Tape is transported to the laser focal volume at a maximum velocity of 356 cm/s, a rate sufficient to accommodate laser repetition rates of 1 kHz. The transport is fully vacuum compatible and can be retracted and then isolated from the laser plasma vacuum enclosure during tape reel replacement. The operating characteristics of the transport are described.

Soft-x-ray projection lithography experiments using Schwarzschild imaging optics.

Soft-x-ray projection imaging is demonstrated by the use of 14-nm radiation from a laser plasma source and a single-surface multilayer-coated ellipsoidal condenser. Aberrations in the condenser and the Schwarzschild imaging objective are characterized and correlated with imaging performance. A new Schwarzschild housing, designed for improved alignment stability, is described.

Effect of UCL on aided Articulation Index calculation.

Nine hearing threshold patterns and uncomfortable loudness level combinations were used in comparing three hearing aid prescriptive procedures by means of a modified Articulation Index. In a minority of the comparisons a small dynamic range required a reduction from the gain that would have been prescribed. For these cases reducing the real-ear gain, in turn, resulted in a mean lowering of the Articulation Index by 0.03 for POGO and 0.08 for the Berger Method.

Introduction to three current hearing aid fitting methods.

The three hearing aid prescription procedures most frequently used in the United States are summarized: POGO, the Berger Method, and the NAL Method. The gain portion of each of the three is based upon a modification of the 1/2 gain rule, which was originally published by Samuel F. Lybarger. The three methods differ in the number of test frequencies involved and on the amount of gain prescribed at the various frequencies. The Berger and NAL procedures incorporate the speech spectrum in their gain-frequency response formulas. With two representative threshold patterns, POGO and the Berger Method produced a higher Articulation Index than the NAL Method.

Diffraction-limited soft-x-ray projection imaging using a laser plasma source.

Projection imaging of 0.1-microm lines and spaces is demonstrated with a Mo/Si multilayer coated Schwarzschild objective and 14-nm illumination from a laser plasma source. This structure has been etched into a silicon wafer by using a trilevel resist and reactive ion etching. Low-contrast modulation at 0.05-microm lines and spaces is observed in polymethylmethacrylate.

The reliability of MCLs with pure tones and damped wave trains.

Most Comfortable Loudness (MCL) was determined for each of 10 normal-hearing young adults using pulsed pure-tone trains and damped wave trains (DWTs) each at 2.5/sec, at frequencies of .25 and 2 kc/s; 4 MCLs were determined for each of the 4 signal type/frequency combinations. In a bracketing procedure employing steps of 20, 10, and finally 5 db, Ss were permitted to respond only "loud" or "soft" to each short train. Group mean test-retest differences within each stimulus type/frequency combination were only 1-2.5 db for all possible test-to-contiguous-test comparisons, i.e., better than with most other MCL procedures except the descending series in the Method of Limits. However, individual Ss differed by from 15-35 db within the 16 distributions (2 stimulus types X 2 frequencies X 4 replications). No statistical or practical differences were found between pure tones or DWTs, or across frequency. It was suggested that the range of individual differences renders any group mean MCL too imprecise a measure for selecting and prescribing a hearing aid, or for determining the effect that aid may have on an individual's performance.

Comparison of hearing threshold level and most comfortable loudness level in hearing aid prescription.

In three experiments, the predictability of the hearing aid gain actually used by clients was compared with that predicted by using data based upon hearing threshold level and data based upon most comfortable loudness level. At the frequencies tested, the mean difference between the predicted and obtained gain was smaller when based upon prediction from the hearing threshold level. It is concluded that from the standpoint of predicting user's gain, the hearing threshold level provides greater accuracy than does most comfortable loudness level.

Gain requirements of conductive hearing losses.

Individuals with significant air-bone gap were presumed to need the gain used by sensori-neural hearing losses, plus one-fifth of the air-bone gap. The amount of operating gain used by 76 conductive and mixed hearing losses was found to closely approximate the predicted amount, but there were large individual differences. As was expected, a gradual increase in gain was used as the size of the air-bone gap increased. There appeared to be minimal relationship between operating gain differences and the air conduction pure-tone threshold pattern, but some relationship to the underlying conductive pathology.

A reexamination of the one-half gain rule.

A one-half gain rule for hearing aid fitting based on the unaided average hearing threshold level was first proposed by S. F. Lybarger. From records on almost 500 clients with sensorineural loss for whom hearing aids were prescribed and fitted, the functional gain for speech reception threshold, 500 Hz, and the average of 1000 and 2000 Hz was examined. The one-half gain rule was found to be valid for speech reception threshold except with mild hearing losses where the gain obtained was a little less than one-half the unaided hearing threshold level. The one-half gain rule is easily computed and provides a good first-order approximation of operating gain needs.

Comfortable loudness judgments for discrete frequency signals.

The test-retest reliability of Most Comfortable Loudness Level (MCL) was examined in three experiments using young normal-hearing adults unsophisticated in audiometric testing. Test stimuli included pure tones, narrow-band noise, and damped wave trains, with presentation by ascending, descending, and Bekesy procedures. Intersubject reliability was found to be very poor and intrasubject reliability to be only fair. Although instructions to Ss and subjects interpretation of instructions probably affect MCL reliability, the task appears to be inherently variable.

Negative needle deflection of the acoustic reflex in otosclerotics.

The preoperative audiometric and electroacoustic impedance test results of 24 surgically confirmed otosclerotics are reviewed with special attention given to the direction of needle deflection during acoustic reflex testing. Information on the direction of needle deflection during acoustic reflex testing was gathered at 5 or 10 dB above reflex threshold. In 12 of the 24 patients acoustic reflexes were present, and in each case the response included negative needle deflections. The presence or absence of the acoustic reflex seemed to be related to the reported duration of the hearing loss.

Prescription of hearing aids: a rationale.

A rationale is presented for a hearing aid prescription. Once the choice of ear(s) to be fitted is determined and whether air or bone conduction fitting is appropriate, output and gain-frequency response characteristics are prescribed on the basis of audiometric test data. The specific prescription data for ouptut are based on uncomfortable loudness levels, and gain-frequency response data are based on a formula that was determined by imposing typical speech parameters over a given hearing loss. A hearing aid prescription is not only intended to predict amplification needs but, just as important, it also provides a method for testing the results of those predictions.

Genealogy of the words "audiology" and "audiologist".

A chronology of the use of the words Audiology and Audiologist is traced through a number of American professional and trade journals. The coining of the word Audiology has been credited variously to Mayer B. A. Schier, Willard B. Hargrave, Stanley Nowak, Norton Canfield, and Raymond Carhart. Attempts to document published use of the word before 1946 were unsuccessful.

Early bone conduction hearing aid devices.

The concept of bone conduction hearing is old. By the 16th century the conduction of sound by a rod or the staff of a spear was reported by a number of writers; however, these writers considered these phenomena as a curiosity rather than having practical value. In the 17th century, John Bulwer and George Sibscota, both interested in the deaf and their education, applied the bone conduction phenomenon as an aid to defective hearing. Soon, independent reports from Germany, France, and Italy also described bone conduction rod devices as aids to impaired hearing. In 1879, the Audiphone, a hearing fan that operated by bone conduction, was patented. The invention of the Audiphone triggered the development and sale of a number of similar devices that had considerable popularity until the invention of the carbon-electric hearing aid in the early 1900s.