Ambient noise levels in nursing homes: implications for audiometric assessment.

Conducting hearing tests and hearing screenings in the nursing home environment can be a challenge. One issue which may affect the validity of the test results is the level of ambient noise in those facilities when a sound-treated booth is not available. This study sampled the ambient noise levels in ten different nursing homes and compared those results to the ANSI S3.1--1999 criteria for maximum permissible ambient noise levels. Based on the results of this investigation, the use of insert earphones for air conduction assessments is recommended when a sound-treated booth is unavailable and noise levels exceed the ANSI criteria. Other suggestions regarding air-conduction and bone-conduction assessments are discussed.

Ambient noise levels in mobile audiometric testing facilities: compliance with industry standards.

Excessive ambient noise levels in audiometric test booths may elevate and therefore invalidate hearing thresholds of employees included in a hearing conservation program. This study was conducted to determine if a sample of mobile test vans and trailers operating in the Midwest met the 1983 Occupational Safety and Health Administration (OSHA) maximum permissible ambient noise levels (MPANLs), the MPANLs in the American National Standards Institute (ANSI) S3.1-1991, and the suggested National Hearing Conservation Association (NHCA) values. Ambient noise levels were measured in 13 audiometric test booths contained in 12 different industrial mobile test vans and trailers operating in the Midwest. Results indicated that all 13 (100%) of the industrial mobile test vans and trailers evaluated complied with 1983 OSHA permissible levels and the NHCA 1996 recommended levels. With regard to the 1991 ANSI MPANLs, 5 (38%) of the 13 booths were in compliance at all frequencies. Those that failed did so at 125, 250, and 500 Hz. It appears that the NHCA levels need to be used for all hearing conservation programs with respect to compliance for noise levels in mobile audiometric test booths.

Otolithic evoked potentials: a new technique for vestibular studies.

Evoked potentials, EP, are time-locked electroencephalographic voltages bearing temporal relation to an excitatory stimulus, recorded by scalp electrodes and an averaging computer. This paper reports the first apparent recording of otolithic EP. Thirty-nine students on a tilt table underwent head drop conditions stimulatory to the otolithic maculas. The wave-form obtained resembles neither auditory, visual, somatosensory or semicircular EP. Otolithic EP provide heretofore unavailable insights into the electrophysiology of the macular generators, VIII nerve, and related central processing.

Noise reduction characteristics of prefabricated sound-isolating enclosures: a laboratory, field measurement, and theoretical analysis.

The noise reduction characteristics of prefabricated sound-isolating enclosures were evaluated. Two enclosures from each of two manufacturers were evaluated for noise reduction characteristics following ASTM 596-78 methods. Thirteen enclosures were field-evaluated for noise reduction using two different procedures. The differences between laboratory- and field-determined noise reduction measures are considered and a theoretical model of noise reduction by audiometric enclosures is evaluated.

A comparative study of alternative bone-conduction calibration methods.

The accepted instrument for calibrating the bone-conduction section of an audiometer is the artificial mastoid. For a variety of reasons, alternative calibration methods are in general use. Three common methods are: (1) the input voltage method; (2) the real-ear threshold method using normal-hearing listeners; and (3) the real-ear threshold method using subjects with sensorineural hearing loss. The present investigation compared these methods for both accuracy and efficiency. There were no significant differences in accuracy found among the three calibration methods. Substantial differences in efficiency were noted, however. When accuracy and efficiency are considered, the input voltage method appears to be the best alternative method for calibrating the bone-conduction system of an audiometer.

Relative ear protector performance in high vs low sound levels.

The attenuation of one specific ear protector was determined for a group of five normal hearing subjects and a group of five hearing impaired subjects. The hearing impaired group yielded significantly less attentuation than the normal hearing group. Since the measuring sound intensity level was high for the hearing impaired listeners and low for the normal listeners, it appears that a threshold procedure using normal subjects, as presented in the American standard (ANSI S3.19-1974), may overestimate the actual attenuation of ear protectors in most noisy environments.

The manual LOT test.

This study was conducted to determine the feasibility of a manual variation of the lengthened off-time (LOT)-Békésy test. The procedure requires that the audiologist vary the attenuator of an audiometer while the signal paradigms of the LOT test are delivered to the patient. Ten nonorganic hearing loss subjects were tested using the automatic LOT test and the manual LOT test. Results were equivalent to the automatic test lending support for the new procedure. The technique can be used with most wide-range audiometers without the additional expense of an automatic recording device.

Input-voltage method of bone-conduction calibration.

Several methods have been proposed for calibrating the bone-conduction section of an audiometer. Because of its low cost and ease of implementation, the input-voltage method is attractive. Only one previous investigation has assessed this calibration method and found it to be lacking. With the availability of updated "required voltages," a reexamination of this calibration method was warranted. Audiometric corrections were determined for 21 combinations of audiometers and bone vibrators at five test frequencies with an artificial-mastoid system. These corrections were compared with those determined with the input-voltage method. The latter yielded corrections that agreed directly with or deviated no more than 5 dB from artificial-mastoid corrections 93.4% of the time and deviated by 10 dB only 6.6% of the time. The use of the input-voltage method for clinical calibration is advocated in the absence of an artificial mastoid.

The LOT test and school-age children.

The LOT test was administered to 100 normal-hearing subjects ranging in age from seven years, six months to 10 years, six months. The test was conducted at 500, 1000, 2000, and 4000 Hz with 99 subjects who were able to perform the required task. The LOT test misclassified (false-positive result) only 4% of the normal-hearing children at 1000 Hz. The test misclassified 3% at 2000 Hz, 3% at 4000 Hz, and 14% at 500 Hz. A new criterion for the use of the LOT test with children is proposed which reduced the percentage of misclassification to 2% at 1000, 2000, and 4000 Hz. The frequency of 500 Hz is not recommended for the preadolescent population.