Speech Intensity Response to Altered Intensity Feedback in Individuals With Parkinson's Disease

Purpose Hypophonia (low speech intensity) is the most common speech symptom experienced by individuals with Parkinson's disease (IWPD). Previous research suggests that, in IWPD, there may be abnormal integration of sensory information for motor production of speech intensity. In the current study, intensity of auditory feedback was systematically manipulated (altered in both positive and negative directions) during sensorimotor conditions that are known to modulate speech intensity in everyday contexts in order to better understand the role of auditory feedback for speech intensity regulation. Method Twenty-six IWPD and 24 neurologically healthy controls were asked to complete the following tasks: converse with the experimenter, start vowel production, and read sentences at a comfortable loudness, while hearing their own speech intensity randomly altered. Altered intensity feedback conditions included 5-, 10-, and 15-dB reductions and increases in the feedback intensity. Speech tasks were completed in no noise and in background noise. Results IWPD displayed a reduced response to the altered intensity feedback compared to control participants. This reduced response was most apparent when participants were speaking in background noise. Specific task-based differences in responses were observed such that the reduced response by IWPD was most pronounced during the conversation task. Conclusions The current study suggests that IWPD have abnormal processing of auditory information for speech intensity regulation, and this disruption particularly impacts their ability to regulate speech intensity in the context of speech tasks with clear communicative goals (i.e., conversational speech) and speaking in background noise.

Effect of Number of Electrodes Used to Elicit Electrical Stapedius Reflex Thresholds in Cochlear Implants

<b><i>Introduction:</i></b> When mapping cochlear implant (CI) patients with limited reporting abilities, the lowest electrical stimulus level that produces a stapedial reflex (i.e., the electrical stapedius reflex threshold [eSRT]) can be measured to estimate the upper bound of stimulation on individual or a subset of CI electrodes. However, eSRTs measured for individual electrodes or a subset of electrodes cannot be used to predict the global adjustment of electrical stimulation levels needed to achieve comfortable loudness sensations that can be readily used in a speech coding strategy. In the present study, eSRTs were measured for 1-, 4-, and 15-electrode stimulation to (1) determine changes in eSRT levels as a function of the electrode stimulation mode and (2) determine which stimulation mode eSRT levels best approximate comfortable loudness levels from patients’ clinical maps. <b><i>Methods:</i></b> eSRTs were measured with the 3 different electrical stimulation configurations in 9 CI patients and compared with behaviorally measured, comfortable loudness levels or M-levels from patients’ clinical maps. <b><i>Results:</i></b> A linear, mixed-effects, repeated-measures analysis revealed significant differences (<i>p</i> &#x3c; 0.01) between eSRTs measured as a function of the stimulation mode. No significant differences (<i>p</i> = 0.059) were measured between 15-electrode eSRTs and M-levels from patients’ clinical maps. The eSRTs measured for 1- and 4-electrode stimulation differed significantly (<i>p</i> &#x3c; 0.05) from the M-levels on the corresponding electrodes from the patients’ clinical map. <b><i>Conclusion:</i></b> eSRT profiles based on 1- or 4-electrode stimulation can be used to determine comfortable loudness level on either individual or a subset of electrodes, and 15-electrode eSRT profiles can be used to determine the upper bound of electrical stimulation that can be used in a speech coding strategy.

EFFECT OF AUDITORY DISTRACTION ON HAND AND FOOT REACTION TIME AMONG AGEING MALAYSIAN AUTOMOBILE DRIVERS

The involvement of ageing drivers in traffic accidents were reported but little cited on the severity of auditory driving distractions. Driving distraction contributes to increases in reaction time which can lead to safety traffic risks. Thus, in this study, hand and foot reaction times were measured in response to different distractions within the identical simulated driving route. The task varies in a controlled setting where soundless distractions were present, Comfortable Loudness Level (CLL), Uncomfortable Loudness Level (ULL) auditory distractions, and phone call distraction. Participants were among 40 Malaysian driving license holders consists of 57.5% males and 42.5% females with age mean, (M=51.83, SD=14.058). Results indicated that both hand and foot reaction time were shortest for CLL and longest during phone call. Ageing male scored shortest hand reaction time of 1.15s during CLL distraction. For foot reaction time, ageing male scores shortest of 0.92s for both CLL and no distractions. Pearson’s coefficient of correlation shows r>0.5. The results indicated hand reaction time was affected by foot reaction time (r=0.665), was significantly more for foot when compared with hand, could be because of difference in nerve conduction velocity and movement time of the hand when compared with that of foot.

Prediction of Software-Based Sentence-in-Noise Recognition Thresholds of Hearing-Impaired Listeners

Purpose: Although hearing-impaired (HI) listeners often have difficulty understanding in noise as their primary complaints, the speech-in-noise intelligibility test is not conducted as a standard audiologic test battery. This study investigated whether the speech audiometry in quiet accurately reflects the sentence-in-noise intelligibility of HI listeners. Methods: Sixty-two HI listeners participated. All the HI listeners had symmetrical high-frequency hearing loss and bilaterally worn hearing aids. Twenty-five normal-hearing (NH) listeners also participated as a control group. The unaided word and sentence recognition scores (WRS and SRS) were obtained in quiet at individually determined most comfortable loudness level. With bilateral hearing aids, the aided WRS and SRS were evaluated at a normal conversational level. The software-based Korean Matrix sentence in noise test was administered at a fixed level (65 dB SPL) of noise while adjusting the sentence level adaptively based on the listener’s response. The signal-to-noise ratio (SNR) required to achieve 50% intelligibility (speech recognition thresholds, SRTs) was obtained. Results: On average, the aided SRT of HI listeners was 0.1 dB SNR, and the mean SRT of NH adults was -8.91 dB SNR. The Matrix sentence-in-noise intelligibility was not sufficiently explained by the unaided WRS or unaided SRS. Conclusion: A traditional measure of the unaided speech-in-quiet recognition cannot accurately predict the aided speech-innoise intelligibility. Clinically, a software-based sentence-in-noise intelligibility test is recommended to directly confirm the actual benefits of hearing aid in noisy situations.

Loudness and Satisfaction Ratings for Hearing Aid Users

Background: Hearing aids amplify low-intensity sounds to make them audible while keeping high-intensity sounds at an acceptable loudness for listeners with impaired hearing. Purpose: The purpose of this analysis was to assess loudness and satisfaction at the same time using a combined loudness and satisfaction questionnaire to rate 18 everyday environmental sounds. Research Design: Ten sets of data from four studies, covering three conditions, were analyzed. The three conditions were unaided, wide dynamic range compression (WDRC), and adaptive dynamic range optimization (ADRO®). In total, there were 61 subjects giving over 3,000 pairs of ratings for loudness and satisfaction. Results: The analysis found a strong relationship between loudness and satisfaction ratings for this set of listeners and conditions. The maximum satisfaction ratings corresponded to sounds with “comfortable” loudness ratings. Satisfaction was lowest for sounds that were “uncomfortably loud.” Sounds that were very soft or inaudible also received low satisfaction ratings unless the sounds were expected to be soft, such as the sound of one's own breathing. Conclusions: Hearing aid fittings that place most sounds at a comfortable level are likely to be more satisfactory than hearing aid fittings that produce more sounds close to hearing thresholds or discomfort levels. Aided conditions gave higher loudness and satisfaction ratings than the unaided condition, and the ADRO hearing aids gave significantly higher satisfaction ratings than the WDRC hearing aids.

Customized Electric Suppression of Tinnitus in CI Subjects

Problem To determine the degree of tinnitus suppression in cochlear implant patients by systematically varying stimulation parameters as a function of rate, level, and electrode. Methods Five cochlear implant subjects with ipsilateral or bilateral tinnitus were included. Implants were stimulated at a basal, middle, and apical electrode, at 100pps and 5000 pps, at perceived level quieter than the tinnitus and at the most comfortable loudness level. Patients reported stimulus and tinnitus perception on a ten-point scale every 30 seconds during and after stimulus delivery. Results All subjects reported near or complete suppression of tinnitus under one or more test conditions. Complete accommodation to the stimulus occurred often, thus during suppression patients perceived very little sound or total silence. Residual inhibition lasted up to twenty minutes. Two of the subjects noted suppression when low rate stimulation was delivered to an apical electrode. One patient responded only to high rate stimulation to an apical electrode. The remaining two patients reported suppression under multiple conditions. One subject had the most dramatic and consistent effects with low rate stimulation to a middle electrode; high rate stimulation caused rebound tinnitus of up to five minutes. Conclusion All patients experienced tinnitus suppression with electrical stimulation. Low rate stimulation overall was more effective in our subject group, and in two cases was the only effective suppressor. Significance Previous studies utilized only high rates of stimulation, and treatment failures occurred. Electrical stimulation is an effective, reproducible, and well-tolerated treatment for tinnitus but stimulus customization is required on an individual basis.