Laura Ann Wilber

Reference thresholds for the ER‐3A insert earphone

Several recent studies have demonstrated that the ER-3A insert earphone may sometimes be directly substituted, without recalibrating, for a TDH-39/MX-41AR earphone. However, most available data have not been reduced to a form suitable for establishing a revised estimate of the reference threshold levels. This article reports such a data analysis performed on the results of five recent studies. The mean data from the five studies are typically within 1 dB of the provisional reference threshold SPLs given by the ER-3A manufacturer for calibration in a (HA-1) 2-cc coupler. After converting the mean data to equivalent Zwislocki-coupler-type ear simulator SPLs at each of the reported audiometric frequencies (125, 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz), agreement within 1.5 dB was seen with the revised estimate of minimum audible pressures given by Killion [J. Acoust. Soc. Am. 63, 1501-1508 (1978)]. Either the manufacturers provisional SPLs or the average results from this study may be used with little noticeable difference for most purposes.

Normal and learning disabled children's central auditory processing skills: an experimental test battery.

The performance of normal children (N = 13) and learning disabled children (N = 26) on an experimental battery of central auditory processing (CAP) tasks was examined. The battery included low-pass filtered speech (LPFS), binaural fusion (BF), time-compressed speech (TC), and dichotic monosyllables (DM) tests. The learning disabled subjects were classified as having normal (LD/N) or significantly impaired (LD/LD) auditory perceptual skills on the basis of a pretest battery of auditory language tests. The normal (N/N) subjects and nonauditory learning disabled (LD/N) subjects tended to perform alike across measures. The auditorily impaired (LD/LD) subjects tended to perform significantly poorer than their normal agemates. The results emphasized the heterogeneity of the learning disabled population. In addition, the results suggested a potentially useful “at risk” criterion when a CAP test battery is used in the assessment of auditory perceptual impairment among children.

Comparing two methods to measure preferred listening levels of personal listening devices

The potential risk to hearing that mass-storage personal listening devices (PLDs) pose remains unclear. Previous research in this area has either focused on maximum outputs of these devices or on ear-canal measurements of listening levels that could not be compared to standards of occupational noise exposure. The purpose of this study was to compare two standard measurement protocols [ISO 11904-1 (2002), Switzerland; ISO 11904-2 (2004), Switzerland] for the measurement of preferred listening levels of PLD. Noise measurements, behavioral thresholds, and oral interviews were obtained from 30 (18-30 years) PLD users. Preferred listening levels for self-selected music were determined in quiet and background noise using a probe microphone, as well as in the DB-100 ear simulator mounted in KEMAR. The ear-canal measurements were compensated for diffuse-field. Only one of the subjects was found to be listening at hazardous levels once their reported daily usage was accounted for using industrial workplace standards. The variance across subjects was the smallest in the ear-canal measurements that were compensated for diffuse-field equivalence [ISO 11904-1 (2002), Switzerland]. Seven subjects were found to be listening at levels above 85 dBA based on measurements obtained in the KEMAR and then compensated for diffuse-field equivalence.

Comparison of two hearing aid receiver-amplifier combinations using sound quality judgments

Sound quality judgments were obtained on two binaural pairs of laboratory hearing aids with similar battery drain. One pair had a traditional low-current-drain “starved Class A” output stage. The other had a new (at the time) “Class D” output stage. Speech and music reproduction was rated, for seven input levels between 70 and 100 dB SPL, on an overall quality scale by juries of normal-hearing and hearing-impaired subjects. The same subjects also were asked to assign a dollar value to each condition by answering the question “What would you pay for a hearing aid that sounded like that?” Both subject groups rated the hearing aids with the Class D output stage as having superior sound quality across a variety of input levels and test materials, consistent with objective distortion measurements. On the average, each one-percentage point increase in sound quality rating corresponded to a

Comparability of Two Commercially Available Artificial Mastoids

6.75 increase in perceived value in these experiments.

Reference threshold levels for the ER‐3A insert earphone

The new ANSI Standard S3.13‐1972 for an artificial headbone lists in its appendix suggested threshold values for audiometric bone conduction calibration using a Beltone artificial mastoid. Two sets of comparisons were recently made between the Beltone 5A and the Bruel & Kjaer 4930 artificial mastoids. The average values of these comparisons are given to provide numbers which may be related to those in the ANSI appendix when using a Bruel & Kjaer artificial mastoid.

Significance and detection of conductive lesions in children with multiple handicaps

Two sets of provisional reference threshold sound pressure levels have been provided by the manufacturer for the calibration of the ER‐3A insert earphone. One set is for use with the B&K DB‐0138 coupler (an HA‐2 2‐cc coupler that comes with a 5‐mm‐diam by 2‐mm‐long stainless steel coupling nipple preceding the 18 mm of 3‐mm‐diam earmold‐simulation portion specified in S3.7‐1973), and the other set is for use with the HA‐1 coupler (the standard “In The Ear hearing aid” 2‐cc coupler) with a foam eartip sealed directly to the top surface of the coupler. Several recent studies have demonstrated that the ER‐3A may be directly substituted, without recalibrating, for a TDH‐39/MX‐41AR earphone in some cases, but most available data have not been reduced to a form suitable for establishing a revised estimate of the reference threshold levels. This paper reports the results of such a data analysis.

Acoustic Immittance, Absorbance, and Reflectance in the Human Ear Canal

Abstract This report discusses the importance of finding conductive lesions in multiply handicapped children both from a medical and communicative point of view. The use of acoustic impedance measurements is discussed as a procedure for determining the presence or absence of conductive lesions. It is emphasized that children may have conductive lesions along with sensorineural hearing losses and that care must be taken to find out if this is the case.

Use of an Adapter Ring for Calibration of Large Circumaural Earphones

Ear canal measurements of acoustic immittance (a term that groups impedance and its inverse, admittance) and the related quantities of acoustic reflectance and power absorbance have been used to assess auditory function and aid in the differential diagnosis of conductive hearing loss for over 50 years. The change in such quantities after stimulation of the acoustic reflex also has been used in diagnosis. In this article, we define these quantities, describe how they are commonly measured, and discuss appropriate calibration procedures and standards necessary for accurate immittance/reflectance measurements.

Variability in Bone‐Conduction Thresholds

Routine calibration of large circumaural earphones has long been a problem due to lack of a standard coupler, variability found with placement on a brass plate coupler, and difficulties in probe tube calibration techniques. In order to provide a practical solution to the above problems so that a pair of large circumaural (Pedersen) earphones could be used routinely, four studies were carried out at UCLA. In these studies, a Plexi‐glass adapter ring was developed that, when fitted with a standard artificial ear and attached to the earphones, furnished a method whereby routine acoustic calibration of the earphones could be carried out easily and repeatedly. Comparisons were made between the Pedersen earphones and TDH 39 earphones using: (1) the adapter ring and artificial ear; (2) a probe tube; and (3) psychophysical techniques. These comparisons made it possible to achieve a method for routine calibration of the large circumaural earphones. The above studies also indicated some problem areas in the use of certain psychophysical techniques such as loudness balancing.