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PubMed2004

Rate and loudness manipulations in dysarthria: acoustic and perceptual findings.

Both rate reduction and increased loudness reportedly are associated with an increase in the size of the articulatory-acoustic working space and improved acoustic distinctiveness for speakers with dysarthria. Improved intelligibility also has been reported. Few studies have directly compared rate and loudness effects for speakers with dysarthria, however, although rate reduction and increasing vocal loudness are common treatment techniques. In the current study, 15 speakers with dysarthria secondary to multiple sclerosis, 12 speakers with dysarthria secondary to Parkinson's disease (PD), and 15 healthy controls read a passage in habitual, loud, and slow conditions. Rate and loudness variations were elicited using magnitude production. Acoustic measures included articulatory rate, sound pressure level, vowel space area, first moment difference measures, and F2 trajectory characteristics for diphthongs. Ten listeners scaled intelligibility for reading passages produced by the speakers with dysarthria. Relationships between intelligibility estimates and acoustic measures were determined by regression analysis. All speaker groups reduced articulatory rate for the slow condition and increased vocal intensity for the loud condition, relative to the habitual condition. Vowel acoustic distinctiveness, as indexed by vowel space area, was maximized in the slow condition, but stop consonant acoustic distinctiveness, as indexed by first moment difference measures, was maximized in the loud condition. F2 slope measures for diphthongs were not consistently affected by rate or loudness. Scaled intelligibility for speakers with PD also improved in the loud condition relative to both the habitual and slow conditions. Intelligibility estimates for speakers with dysarthria, however, were not strongly related to acoustic measures of supraglottal behavior. Findings are compared with previous studies, and hypotheses for future treatment studies are discussed.

Adult↗
PubMed2005

Effect of slow-acting wide dynamic range compression on measures of intelligibility and ratings of speech quality in simulated-loss listeners.

The purpose of this study was twofold: (a) to determine the extent to which 4-channel, slow-acting wide dynamic range amplitude compression (WDRC) can counteract the perceptual effects of reduced auditory dynamic range and (b) to examine the relation between objective measures of speech intelligibility and categorical ratings of speech quality for sentences processed with slow-acting WDRC. Multiband expansion was used to simulate the effects of elevated thresholds and loudness recruitment in normal hearing listeners. While some previous studies have shown that WDRC can improve both speech intelligibility and quality, others have found no benefit. The current experiment shows that moderate amounts of compression can provide a small but significant improvement in speech intelligibility, relative to linear amplification, for simulated-loss listeners with small dynamic ranges (i.e., flat, moderate hearing loss). This benefit was found for speech at conversational levels, both in quiet and in a background of babble. Simulated-loss listeners with large dynamic ranges (i.e., sloping, mild-to-moderate hearing loss) did not show any improvement. Comparison of speech intelligibility scores and subjective ratings of intelligibility showed that listeners with simulated hearing loss could accurately judge the overall intelligibility of speech. However, in all listeners, ratings of pleasantness decreased as the compression ratio increased. These findings suggest that subjective measures of speech quality should be used in conjunction with either objective or subjective measures of speech intelligibility to ensure that participant-selected hearing aid parameters optimize both comfort and intelligibility.

Acoustic Stimulation↗
PubMed2005

Auditory frequency discrimination in children with specific language impairment: a longitudinal study.

It has been proposed that specific language impairment (SLI) is caused by an impairment of auditory processing, but it is unclear whether this problem affects temporal processing, frequency discrimination (FD), or both. Furthermore, there are few longitudinal studies in this area, making it hard to establish whether any deficit represents a developmental lag or a more permanent deficit. To address these issues, the authors retested a group of 10 children with SLI and 12 control children first tested 42 months previously. At Time 1, the children with SLI (between 9 and 12 years of age) had significantly elevated FD thresholds compared to the matched controls. At Time 2, the thresholds of both groups had improved, but the children with SLI still had poorer FD thresholds than those of the controls. To assess temporal resolution, auditory backward masking was measured and it was found that most of the children with SLI performed as well as the controls, but 2 children had exceptionally high thresholds. There was also greater variability among the children with SLI compared to that measured among the controls on the FD task. These studies indicate considerable heterogeneity in auditory function among children with SLI and suggest that, as with auditory temporal deficits, difficulties in FD discrimination are important in this population.

Adolescent↗
PubMed2006

The relationship of vocal loudness manipulation to prosodic F0 and durational variables in healthy adults.

This investigation was motivated by observations that when persons with dysarthria increase loudness their speech improves. Some studies have indicated that this improvement may be related to an increase of prosodic variation. Studies have reported an increase of fundamental frequency (F0) variation with increased loudness, but there has been no examination of the relation of loudness manipulation to specific prosodic variables that are known to aid a listener in parsing out meaningful information. This study examined the relation of vocal loudness production to selected acoustic variables known to inform listeners of phrase and sentence boundaries: specifically, F0 declination and final-word lengthening. Ten young, healthy women were audio-recorded while they read aloud a paragraph at what each considered normal loudness, twice-normal loudness, and half-normal loudness. Results showed that there was a statistically significant increase of F0 declination, brought about by a higher resetting of F0 at the beginning of a sentence and an increase of final-word lengthening from the half-normal loudness condition to the twice-normal loudness condition. These results suggest that when some persons with dysarthria increase loudness, variables related to prosody may change, which in turn contributes to improvement in communicative effectiveness. However, until this procedure is tested with individuals who have dysarthria, it is uncertain whether a similar effect would be observed.

Adolescent↗
PubMed1979

Effects of speech materials on the loudness discomfort level.

Clinicians have used speech stimuli when measuring the loudness discomfort level (LDL) to determine the upper intensity limit for test stimulus presentation, and to select the saturation sound pressure level for an individual's hearing aid. Because little research has investigated the effects of speech stimuli on the LDL, this study was undertaken to compare LDLs using six commercially available speech materials on 120 normally hearing listeners. Our comparisons showed no significant differences between the mean scores for any of the speech stimuli. These findings suggest that any differences in the mean LDLs among studies probably are not attributable to the speech stimuli. The intrasession reliability of LDL measurement was also assessed using a modified method of limits procedure with 2-dB increments and instructions stressing initial discomfort. It was concluded that examiners probably could attain a high degree of reliability by simply averaging the results of two ascending trials, because 95% of these test/retest differences did not exceed 6 dB. Our findings were integrated with previous studies in terms of: (1) test stimuli; (2) listener experience; (3) instructional set; and (4) psychophysical method. This discussion points to many unanswered questions and concludes that the LDL should be interpreted very cautiously. Moreover, it is suggested that the stimuli selected for LDL measurement should reflect the examiner's purpose.

Acoustic Stimulation↗
PubMed1980

Loudness discomfort levels: a clinical procedure for hearing aid evaluations.

Before any amplification system is evaluated, prescribed, or recommended, the audiologist must determine that the limits of its output across frequency are not greater than the levels at which clients experience discomfort, that is, their Loudness Discomfort Levels (LDL). After reviewing terminology, reasons for obtaining LDLs, and several sources of variability in LDL measurements, a new clinical LDL measurement procedure for hearing aid evaluations is suggested. The main aspects of this procedure are the instructions (from Morgan, Wilson and Dirks, 1974), the stimuli (sweep-frequency pulsed pure tones), the psychophysical method (tracking procedure), the calibration of the stimuli (by a hearing aid receiver attached to a 2 cm3 coupler), and the presentation of the stimuli (through the hearing aid receiver coupled to the client's earmold). This technique is suggested as clinically feasible and as a defensible procedure for obtaining LDLs for the purpose of more closely specifying an appropriate SSPL90 curve.

Correction of Hearing Impairment↗
PubMed1982

Overamplification: a well-documented case report.

A well-documented case report is presented in which the use of a high-output hearing aid over a 10-year period resulted in significant threshold shifts in the aided as compared to the unaided ear. At no time did the user experience loudness discomfort and she consistently wanted more gain from the hearing aid, indicating that there is no relationship between loudness discomfort levels and the sound pressure levels at which damage to the auditory system occurs. Difficulties in detecting the cause of the threshold shifts and recommendations for case management are discussed.

Adult↗
PubMed1983

Accuracy of adaptive procedure estimates of PF-max level.

A measure of maximum speech recognition ability (PB max) is often obtained in the clinical audiologic evaluation of patients. However, without developing a complete performance-intensity function (PIF), it is often difficult to determine an appropriate intensity level for measuring PB max. Levitt (1978) has described an adaptive procedure designed to estimate an intensity level at which maximum speech recognition performance could be measured. We have investigated the accuracy of this procedure by comparing speech recognition performance on a CNC word list presented at the level estimated by the adaptive procedure with maximum performance as measured on the listener's performance-intensity function. Using the presentation level indicated by the adaptive procedure, PB max scores were obtained for 12 of 16 normally hearing subjects and 19 of 25 listeners with mild-to-moderate sensorineural hearing loss. Similar accuracy was obtained for the hearing-impaired subjects using a single presentation level of 95 dB SPL, while use of a 40 dB SL speech level would have resulted in a lower proportion of PB-max measurements. Although PB max is most accurately estimated by delineating the entire performance-intensity function, the current results suggest that, if speech recognition is to be measured only at a single level, scores obtained at the level estimated by the adaptive procedure or at 95 dB SPL may serve as reasonable estimates of PB max for listeners with primarily cochlear hearing losses of less than or equal to 50 dB.

Adolescent↗
PubMed1985

Acoustic-reflex dynamics and the loudness-discomfort level.

Acoustic-reflex growth functions and Loudness-Discomfort Level (LDL) measures were obtained for 15 normal-hearing subjects. The hypothesis that signals considered uncomfortably loud occur at intensity levels that produce proportionately equal acoustic-reflex magnitudes was evaluated. Individual reflex growth functions were measured as a function of activator SPL for a 1000-Hz tone, a 4000-Hz tone, and a broadband noise. These growth functions were measured within subjects (two trials) and across subjects in terms of (a) percentage acoustic-impedance change at LDL, (b) percentage acoustic-reactance change at LDL, (c) acoustic impedance at LDL, (d) relative change in acoustic impedance at LDL, and (e) ratio of static acoustic impedance to change in acoustic impedance at LDL. Although the loudness and acoustic-reflex measures demonstrated good reliability across trials, the data showed large variability across subjects and did not support the experimental hypothesis. It was concluded, therefore, that the use of acoustic-reflex measures in the estimation of an individual's LDL is unwarranted.

Acoustic Stimulation↗
PubMed1986

Relationship between pure-tone and speech loudness discomfort levels among hearing-impaired subjects.

The purpose of this study was to investigate how accurately pure-tone (250-6000 Hz) loudness discomfort levels (LDLs) predict speech (CID Test W-22) LDLs. One ear was tested in each of 50 elderly subjects with mild-to-moderate sensorineural hearing loss. The results revealed poor-to-fair correlations (r = 0.00 to 0.42) and large standard errors of estimate (approximately 9.5 dB). Thus, it was concluded that pure-tone LDLs are not accurate predictors of the speech LDL, and, if the clinician wants to ascertain the upper intensity for listening to speech, this measurement must be made directly.

Aged↗
PubMed1986

An evaluation of several rationales for selecting hearing aid gain.

The present study evaluates the rationales underlying several hearing aid selection procedures. The first portion of the evaluation confirms that the gain-selection rationales result in the selection of different hearing aids for a given patient. Nine different audiometric configurations representing varying degrees of flat, sloping, and rising sensorineural hearing loss were considered. The second phase of the evaluation considered how well each procedure achieved the goal of maximizing speech recognition. This analysis made use of the Articulation Index and was applied to each of the nine audiometric configurations. The results of this analysis suggested that, given the ability to adjust the overall gain over a typical range available through most volume controls, any of the procedures could produce optimal aided speech recognition performance. The final portion of the evaluation examined the ability of each procedure to prescribe absolute gain and relative gain (frequency response) that corresponded to that preferred by hearing aid wearers. The data for preferred insertion gain came from a recent investigation by Leijon, Eriksson-Mangold, and Beck-Karlsen (1984). The results of this evaluation suggested that some procedures prescribe gain values closer to those preferred by listeners than others. More data are needed on preferred gain values for a variety of configurations, however, before any one procedure can be recommended over another.

Acoustics↗
PubMed1978

Effect of sensorineural hearing loss on loudness discomfort level and most comfortable loudness judgments.

A simple up-down adaptive procedure was used to estimate the 50% point on the psychometric function for loudness discomfort level (LDL) and the two functions describing the range of most comfortable loudness (MCL) for listeners with sensorineural hearing impairment. For pure tone and speech stimuli, median LDL and MCL levels were observed at relatively constant SPLs for subjects with hearing loss less than or equal to dB HL and at progressively higher SPLs with further increase in hearing loss. Correlation analysis verified a statistically significant relationship between LDL and magnitude of hearing loss. The nonlinear relationship between LDL and hearing loss together with the large intersubject variability in the data suggest that prediction of LDL from hearing threshold would often be highly inaccurate. These results also demonstrate that averaging LDL data across a group of subjects with a wide range of hearing loss may lead to inaccurate conclusions regarding the effects of sensorineural hearing loss on LDL.

Adolescent↗
PubMed1979

Acoustic-reflex growth and loudness.

Acoustic-reflex growth functions and loudness-balance judgments were obtained for three normal-hearing subjects with normal middle-ear function. The hypothesis that acoustic reflex-activating signals producing proportionately equal acoustic-impedance changes are judged equal in loudness was evaluated. The mean acoustic impedance and associated standard deviations were computed for the baseline (static) and activator (reflex) portions of each reflex event. An acoustic-impedance change exceeding two standard deviations of baseline was defined as the criterion acoustic-reflex response. Acoustic impedance was measured as a function of activator SPL for broadband noise and a 1000-Hz tone from criterion magnitude to the maximum acoustic impedance (or 120-dB SPL). This was defined as the dynamic range of reflex growth. Loudness-balance measurements were made for the 1000-Hz tone and broadband noise at SPL's representing 30, 50, and 70% of the individual dynamic range. The data supported the hypothesis.

Acoustic Impedance Tests↗
PubMed1979

The effect of psychophysical method on the loudness of continuous and interrupted pure tones.

Using the Bekesy tracking method for loudness judgement tasks such as most comfortable loudness (MCL) and recalled loudness (RL) measurements, normal listeners have tracked continuous (C) tones at lesser intensities than interrupted (I) tones. The resulting continuous/interrupted (C/I) separations have ranged up to 22 dB. Explanations of the unexpected C/I separations have not been in agreement. The purpose of this study was to investigate whether psychophysical method has a significant effect on the C/I separation. Subjects were six normal-hearing adults, each of whom participated in three practice and ten test sessions of one hour each. Thirty-six experimental conditions were presented. The test signals were C tones, 200/200 msec I tones and 200/800 msec I tones, all at 1 kHz. The reference intensities wer 20, 50 and 80 dB SPL. The four methods were Bekesy tracking method (BTM), method of adjustment (MAdj), method of limits (ML) and method of constant stimuli difference (MCSD). Mean values for Point of Subjective Equality and C/I separation were calculated. C/I separations obtained with the BTM were significantly larger than C/I separations obtained with any other psychophysical method. These results demonstrate that C/I separations obtained during suprathreshold Bekesy tracking tasks by normal hearers are largely caused by the measurement method itself rather than by differences in C and I tone loudness. Time order errors could explain the BTM effect.

Adult↗
PubMed1979

Loudness discomfort level and acoustic reflex threshold for speech stimuli.

Loudness discomfort level (LDL) and acoustic reflex threshold (ART) measurements were obtained from subjects with normal hearing using several speech stimuli, as well as broad-band and speech-spectrum noise. The purpose of the investigation was to determine the LDL for a variety of representative speech samples, and to determine the relationship between the LDL and ART for selected speech and noise stimuli. For all stimuli, LDL measurements were relatively constant, but ART measurements decreased significantly for wide-band noise stimuli as compared with the speech stimuli. Mean differences between the two measures were consistent, but individual subject data were characterized by wide variability precluding accurate prediction of the LDL from ART measurements.

Acoustic Stimulation↗
PubMed1979

Relationship between loudness discomfort level and acoustic reflex threshold for normal and sensorineural hearing-impaired individuals.

The relationship between loudness discomfort level (LDL) and acoustic reflex threshold (ART) was determined by comparing the ART to the LDL obtained by the psychophysical method of constant stimuli. Randomly presented stimuli of 1000 Hz, 2000 Hz, and a multi-talker speech noise were presented to normal and sensorineural hearing-impaired listeners. The listener's task was to judge whether the stimulus was at a level that was: (1) too loud or uncomfortably loud; or (2) not too loud or not uncomfortably loud. Prior to the judgement of the subject acoustic reflex threshold were determined. Both LDL and ART were found to be significantly higher for the hearing-impaired group. For the pure tone stimuli, LDL for the hearing-impaired group was at or below the ART. Significant differences were shown to exist between LDL and ART for each group. A multiple regression analysis indicated significant correlations between LDL and ART. Ranges of prediction error were selected to investigate the ability of ART to predict LDL. Both pure tone and speech ART successfully predicted LDL within +/- 10 dB for a high percentage of the subjects.

Adolescent↗
PubMed1981

Loudness balance calibration of bone conduction vibrators.

An improved monaural loudness balance method of transferring calibration data among three physically dissimilar bone conduction vibrators was compared with the threshold method. In 19 of 21 possible comparisons, absolute differences between the transfer factors obtained with the two methods were 2.5 dB or less, showing that the monaural loudness balance procedure compares favorably with the threshold method.

Adult↗