Theodore S. Bell

Comparison of static and dynamic posturography in young and older normal people

Objective: To measure sway velocity during static and dynamic posturography in “normal’ older people and to determine which tests best distinguish young from older subjects.

A Prospective Study of Posturography in Normal Older People

OBJECTIVE: To follow posturographic measurements over time in a group of normal older subjects to see if sway increases with aging and if sway is greater in those with deteriorating balance and falls.

Posturography and Balance Problems in Older People

OBJECTIVE: To determine which measurements and test conditions on posturography are most useful for identifying balance problems in older people.

Speech recognition and the Articulation Index for normal and hearing‐ impaired listeners

The purpose of this experiment was to determine the applicability of the Articulation Index (AI) model for characterizing the speech recognition performance of listeners with mild-to-moderate hearing loss. Performance-intensity functions were obtained from five normal-hearing listeners and 11 hearing-impaired listeners using a closed-set nonsense syllable test for two frequency responses (uniform and high-frequency emphasis). For each listener, the fitting constant Q of the nonlinear transfer function relating AI and speech recognition was estimated. Results indicated that the function mapping AI onto performance was approximately the same for normal and hearing-impaired listeners with mild-to-moderate hearing loss and high speech recognition scores. For a hearing-impaired listener with poor speech recognition ability, the AI procedure was a poor predictor of performance. The AI procedure as presently used is inadequate for predicting performance of individuals with reduced speech recognition ability and should be used conservatively in applications predicting optimal or acceptable frequency response characteristics for hearing-aid amplification systems.

Recognition of nonsense syllables by hearing‐impaired listeners and by noise‐masked normal hearers

In the present study, speech-recognition performance was measured in four hearing-impaired subjects and twelve normal hearers. The normal hearers were divided into four groups of three subjects each. Speech-recognition testing for the normal hearers was accomplished in a background of spectrally shaped noise in which the noise was shaped to produce masked thresholds identical to the quiet thresholds of one of the hearing-impaired subjects. The question addressed in this study is whether normal hearers with a hearing loss simulated through a shaped masking noise demonstrate speech-recognition difficulties similar to those of listeners with actual hearing impairment. Regarding overall percent-correct scores, the results indicated that two of the four hearing-impaired subjects performed better than their corresponding subgroup of noise-masked normal hearers, whereas the other two impaired listeners performed like the noise-masked normal listeners. A gross analysis of the types of errors made suggested that subjects with actual and simulated losses frequently made different types of errors.

Papillary squamous neoplasms of the head and neck

Papillary squamous neoplasms of the upper respiratory tract are rare variants of squamous cell carcinoma and are related temporally to proliferative verrucous leukoplakia. Fifty‐two cases of papillary squamous neoplasms were selected from 2366 cases of squamous cell carcinoma. This is the first study to characterize the biological behavior of papillary squamous neoplasms. Papillary squamous neoplasms exhibit two distinct, yet sometimes overlapping, histologic patterns including an exophytic papillary and an inverting verrucous morphologic appearance. A high rate of synchronous or metachronous lesions were found, especially with the inverting‐type of papillary squamous neoplasm. Stage T3 and T4 lesions had a high rate of neck metastasis. Early surgical intervention and close long‐term follow‐up is mandatory.

Articulation index predictions of contextually dependent words

Three investigations were conducted to determine the application of the articulation index (AI) to the prediction of speech performance of hearing-impaired subjects as well as of normal-hearing listeners. Speech performance was measured in quiet and in the presence of two interfering signals for items from the Speech Perception in Noise test in which target words are either highly predictable from contextual cues in the sentence or essentially contextually neutral. As expected, transfer functions relating the AI to speech performance were different depending on the type of contextual speech material. The AI transfer function for probability-high items rises steeply, much as for sentence materials, while the function for probability-low items rises more slowly, as for monosyllabic words. Different transfer functions were also found for tests conducted in quiet or white noise rather than in a babble background. A majority of the AI predictions for ten individuals with moderate sensorineural loss fell within +/- 2 standard deviations of normal listener performance for both quiet and babble conditions.

Effect of Vocal Fold Augmentation on Laryngeal Vibration in Simulated Recurrent Laryngeal Nerve Paralysis: A Study of Teflon and Phonogel

Flaccid laryngeal nerve paralysis may be treated by vocal fold augmentation with Teflon injection, which is successful to various degrees depending on the subjective interpretation of the patient or clinician. A new material, Phonogel, consisting of cross-linked bovine collagen, is available but not approved for human use in this area. Ten dogs were submitted to videostroboscopy, photoglottography, electroglottography, and acoustic analysis in the normal state, with simulated recurrent laryngeal nerve paralysis, and with injection of either Teflon or Phonogel. A statistical comparison and the advantages and disadvantages of each material are discussed in relation to this study and its clinical use.

Comparison of speech recognition-in-noise and subjective communication assessment.

A comparison was made between speech recognition performance in conditions of quiet and babble (Speech Perception in Noise Test) and items from a self-assessment scale concerned with communication ability in quiet and noise (Understanding Speech section of Hearing Performance Inventory). Performance on both the speech recognition and self-assessment tests differentiated between normal listeners and individuals with mild-to-moderate sensorineural hearing loss. For the hearing-impaired group, correlations between speech recognition scores and ratings on the self-assessment items were poor, suggesting that performance measured with these tests have only a weak relationship.

The effect of recurrent laryngeal nerve stimulation on phonation in an in vivo canine model.

The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottog‐raphy (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.