Allen A. Montgomery

Description and validation of an LDL procedure designed to select SSPL90.

A new procedure is described for measuring loudness discomfort levels (LDLs) for the purpose of selecting SSPL90 characteristics of hearing aids. The person is seated in sound field wearing a high-output hearing aid (with a known amount of 2 cm3 coupler gain) connected to a personal earmold. The loudness of frequency-specific signals is rated from a series of loudness category descriptors. The LDL is defined in terms of SPL developed in a 2 cm3 coupler, thus making selection of SSPL90 from hearing aid specification sheets practical. Experiments on LDL stability over time and validation of the SSPL90 selection are reported.

Functional communication and executive function in aphasia.

The purpose of this exploratory study was to investigate the relationship between functional communication and executive function ability in aphasia. Twenty‐five participants with aphasia underwent examination with an extensive test battery including measures of functional communication, executive function ability, and language impairment. Compared to published norms, most participants did not perform within normal limits on the executive function tests. As expected, the correlation between severity of language impairment and functional communication ratings exceeded that among the executive functioning and functional communication measures. Eight of ten correlation coefficients for the relationship between executive functioning and functional communication reached statistical significance suggesting a clear relationship between scores on the executive functioning measures and functional communication ability. Based on these results, it appears that decreased executive functioning ability may coincide with decreased functional communication ability in persons with aphasia.

An evaluation of residue features as correlates of voice disorders

Two experiments were conducted to assess the correlations of residue features with some perceptual properties of voice disorders. First, 90 samples of the vowel /a/ produced by patients with various vocal pathologies were analyzed to obtain the residue features, and severity judgments of these vowel samples were obtained. The results of linear multiple regression analysis indicated that the features were highly correlated with the severity ratings. Second, an attempt was made to correlate the residue features with voice qualities. The features were calculated for the vowel /a/ produced by patients with vocal nodules, vocal fold paralysis, and vocal polyps and by normal talkers. Each vowel sample was rated on ten scales of voice quality. The results revealed high correlations among the quality scales so that discrete subject groups could not be formed. Thus, residue features may be useful in assessing the degree of vocal impairment, but their use as correlates of voice quality must await further research.

Reaction-time measures of stutterers and nonstutterers

Abstract Ten adult male stutterers and ten adult male nonstutterers participated in six reaction-time tasks designed to measure manual, acoustic, and laryngeal-region response latencies. The analysis revealed statistically significant differences between the groups for the acoustic data only. The results indicated that acoustic reaction-time differences are not accounted for by the speed of the general laryngeal response.

Brief Report: Perception and Lateralization of Spoken Emotion by Youths with High-Functioning Forms of Autism

The perception and the cerebral lateralization of spoken emotions were investigated in children and adolescents with high-functioning forms of autism (HFFA), and age-matched typically developing controls (TDC). A dichotic listening task using nonsense passages was used to investigate the recognition of four emotions: happiness, sadness, anger, and neutrality. The participants with HFFA did not differ significantly in overall performance from the TDC, suggesting that the pervasive difficulty in processing emotions is not uniformly present in emotions expressed verbally. Both groups demonstrated a left-ear effect for the perception of emotion in nonsense passages, consistent with overall right-hemisphere superiority for this function.

Training auditory-visual speech reception in adults with moderate sensorineural hearing loss.

A new method of training auditory-visual speech reception is described and evaluated on an experimental group of 12 hearing-impaired adult patients. The method involves simultaneous, live presentation of the visible and acoustic components of the therapists speech, where the acoustic signal is degraded under the therapists control with a voice-activated switch. Pre-and post-training performance was assessed with an auditory-visual sentence recognition task. The performance of the experimental group, who received 10 hours of individual training, is described and compared to a control group who received a traditional aural rehabilitation program and to a group of normals who received no training. The experimental training resulted in significantly greater improvement than the control group. A description of the training, including rationale and suggestions for implementation in a clinical setting, is provided.

Sensitivity to isolated and concurrent intensity and fundamental frequency increments by cochlear implant users under natural listening conditions.

Sensitivity to acoustic cues in cochlear implant (CI) listening under natural conditions is a potentially complex interaction between a number of simultaneous factors, and may be difficult to predict. In the present study, sensitivity was measured under conditions that approximate those of natural listening. Synthesized words having increases in intensity or fundamental frequency (F0) in a middle stressed syllable were presented in soundfield to normal-hearing listeners and to CI listeners using their everyday speech processors and programming. In contrast to the extremely fine sensitivity to electrical current observed when direct stimulation of single electrodes is employed, difference limens (DLs) for intensity were larger for the CI listeners by a factor of 2.4. In accord with previous work, F0 DLs were larger by almost one order of magnitude. In a second experiment, it was found that the presence of concurrent intensity and F0 increments reduced the mean DL to half that of either cue alone for both groups of subjects, indicating that both groups combine concurrent cues with equal success. Although sensitivity to either cue in isolation was not related to word recognition in CI users, the listeners having lower combined-cue thresholds produced better word recognition scores.

Multidimensional scaling of quality judgments of speech signals processed by hearing aids.

Perceptual dimensions underlying similarity ratings and preference judgments of the quality of hearing-aid-processed speech were derived via multidimensional-scaling procedures, and were correlated with 15 indices of electroacustic performance to determine those electroacoustic characteristics contributing maximally to quality judgements. Connected discourse was tape recorded through 20 conventional hearing aids and presented in a paired-comparison paradigm to ten normal listeners for similarity ratings and quality preference judgments. Analysis of the group similarity matrices revealed only one definitive perceptual dimension, low-cutoff frequency, that was common to the listeners. In a three-dimensional INDSCAL solution, this electroacoustic factor correlated--0.87 with dimension 1. Listeners strongly preferred hearing aids with relatively low low-cutoff frequencies; dimension 1 correlated--0.76 with their preferences. The quality judgments of some listeners were found via KYST analysis to exhibit a multidimensional structure, with low-cutoff frequency remaining the most salient dimension. Secondary dimensions varied across these several listeners, and included response irregularity, equivalent input noise level, high-cutoff frequency, and intermodulation distortion. Thus, the data provided evidence that, while low-cutoff frequency dominates listener judgments a multidimensional model may underlie the perceptual strategies used by some listeners to form quality judgments of hearing-aid-processed speech.

Performance of High Frequency Impaired Listeners with Conventional and Extended High Frequency Amplification

This study sought to determine if a high-pass hearing aid can provide increased improvement in word recognition and consonant discrimination over that of a conventional high frequency emphasis hearing aid in listeners with hearing loss limited to frequencies above 1 000 Hz. Word and consonant discrimination were assessed in quiet and in the presence of 12 talker speech babble for 10 subjects under three listening conditions: (1) unaided; (2) wearing a conventional high frequency emphasis hearing aid, and (3) wearing an experimental high-pass instrument. The speech testing materials included: (1) Northwestern University Auditory Test No. 6; (2) California Consonant Test, and (3) eight voiceless English consonants. Results suggested that both instruments provided similar benefit in quiet for improving word recognition and resolving consonant errors. For the noise condition, however, the experimental high-pass aid provided a considerable advantage in both word recognition and consonant identification and was particularly sensitive to reducing within- and between-manner voiceless consonant confusions. Furthermore, measurements of real-ear gain revealed that the high-pass aid afforded considerably greater acoustic gain above 4 000 Hz than that shown for the conventional high frequency emphasis hearing aid,20

Simulating the neural correlates of stuttering

For functional neuroimaging studies of stuttering, two challenges are (1) the elicitation of naturally stuttered versus fluent speech and (2) the separation of activation associated with abnormal motor execution from activation that reflects the cognitive substrates of stuttering. This paper reports on a proof-of-concept study, in which a single-subject approach was applied to address these two issues. A stuttering speaker used his insight into his own stuttering behavior to create a list of stutter-prone words versus a list of “fluent” words. He was then matched to a non-stuttering speaker, who imitated the specific articulatory and orofacial motor pattern of the stuttering speaker. Both study participants performed a functional MRI experiment of single word reading, each being presented with the same lexical items. Results suggest that the generally observed right-hemisphere lateralization appears to reflect a true neural correlate of stuttering. Some of the classically reported activation associated with stuttering appears to be driven more by nonspecific motor patterns than by cognitive substrates of stuttering, while anterior cingulate activation may reflect awareness of (upcoming) dysfluencies. This study shows that it is feasible to match stuttering speakers’ utterances more closely to simulated stutters for the investigation of neural correlates of real stuttering. Significant main effects and contrast effects were obtained for the differences between fluent and stuttered speech, and right-hemisphere lateralization associated with real stuttered speech was shown in a single subject.