Biomedical subjects

Pamela E Souza

Publications and source records attributed to Pamela E Souza.

12 recordsLinked to original sources

PubMed2006

Screening for Auditory Impairment-Which Hearing Assessment Test (SAI-WHAT): RCT design and baseline characteristics.

BACKGROUND: Effective screening programs should not merely detect presence of disease, but also lead to long-term benefit. We describe the rationale and design of the first randomized clinical trial to study the long-term effects of routine screening for hearing loss. We also describe the baseline characteristics of the randomized cohort. METHODS: We randomized 2305 veterans age 50 years or older to a control arm without screening, or to screening with: physiologic testing (AudioScope), a self-administered questionnaire (Hearing Handicap Inventory for the Elderly-Screening version [HHIE-S]), or both tests. The primary outcome measure will be hearing aid use one year after screening. We will also study a number of secondary outcomes, including appointments made with and visits to an audiologist, cases of aidable hearing loss, hearing aids dispensed, self-rated communication ability, and hearing-related quality of life. RESULTS: Baseline demographic and health status measures were evenly distributed across the screening arms. The percentage of patients who screened positive for hearing loss was 18.6%, 59.2%, and 63.6% for the AudioScope, HHIE-S, and combined screening arms, respectively. IMPLICATIONS: Long-term results are needed to gain insight into whether the AudioScope is associated with high rates of false negative screening, the HHIE-S is associated with high rates of false positive screening, or a combination of both. Identifying the best screening program will depend on determining which strategy leads to successful hearing aid use.

Female↗

PubMed2006

Combining temporal-envelope cues across channels: effects of age and hearing loss.

The goal of this study was to examine the ability to combine temporal-envelope information across frequency channels. Three areas were addressed: (a) the effects of hearing loss, (b) the effects of age and (c) whether such effects increase with the number of frequency channels. Twenty adults aged 23-80 years with hearing loss ranging from mild to severe and a control group of 6 adults with normal hearing participated. Stimuli were vowel-consonant-vowel syllables. Consonant identification was measured for 5 conditions: (a) 1-channel temporal-envelope information (minimal spectral cues), (b) 2-channel, (c) 4-channel, (d) 8-channel, and (e) an unprocessed (maximal spectral cues) speech condition. Performance of listeners with normal hearing and listeners with hearing loss was similar in the 1-channel condition. Performance increased with the number of frequency channels in both groups; however, increasing the number of channels led to smaller improvements in consonant identification in listeners with hearing loss. Older listeners performed more poorly than younger listeners but did not have more difficulty combining temporal cues across channels than in a simple, 1-channel temporal task. Age was a significant predictor of nonsense syllable identification, whereas amount of hearing loss was not. The results support an age-related deficit in use of temporal-envelope information with age, regardless of the number of channels.

Adult↗

PubMed2006

Neural representation of amplified speech sounds.

OBJECTIVE: To determine if (1) evoked potentials elicited by amplified speech sounds (/si/ and /[symbol: see text]/) can be recorded reliably in individuals, (2) amplification alters neural response patterns, and (3) different amplified speech sounds evoke different neural patterns. DESIGN: Cortical evoked potentials were recorded in sound field from seven normal-hearing young adults in response to naturally produced speech tokens /si/ and /[symbol: see text]/ from the Nonsense Syllable Test. With the use of a repeated-measures design, subjects were tested and then retested within an 8-day period in both aided and unaided conditions. RESULTS: (1) Speech-evoked cortical potentials can be recorded reliably in individuals in both aided and unaided conditions. (2) Hearing aids that provide a mild high-frequency gain only subtly enhance peak amplitudes relative to unaided cortical recordings. (3) If the consonant-vowel boundary is preserved by the hearing aid, it can also be detected neurally, resulting in different neural response patterns for /si/ and /[symbol: see text]/. CONCLUSIONS: Speech-evoked cortical potentials can be recorded reliably in individuals during hearing aid use. A better understanding of how amplification (and device settings) affects neural response patterns is still needed.

Acoustic Stimulation↗

PubMed2006

Measuring the acoustic effects of compression amplification on speech in noise.

This letter contains a description of an inversion technique that allows for separation of speech and noise and its application to quantifying the acoustic effects of wide-dynamic-range compression (WDRC) on speech in background noise. Three main findings are reported: that fast-acting WDRC further degrades signal-to-noise ratio; that the effective compression ratio is lower for speech in noise than speech in quiet; and that in contrast to speech in quiet, the amplitude envelope of speech is mostly unaffected when compressed in background noise.

Algorithms↗

PubMed2006

New perspectives on assessing amplification effects.

Clinicians have long been aware of the range of performance variability with hearing aids. Despite improvements in technology, there remain many instances of well-selected and appropriately fitted hearing aids whereby the user reports minimal improvement in speech understanding. This review presents a multistage framework for understanding how a hearing aid affects performance. Six stages are considered: (1) acoustic content of the signal, (2) modification of the signal by the hearing aid, (3) interaction between sound at the output of the hearing aid and the listener's ear, (4) integrity of the auditory system, (5) coding of available acoustic cues by the listener's auditory system, and (6) correct identification of the speech sound. Within this framework, this review describes methodology and research on 2 new assessment techniques: acoustic analysis of speech measured at the output of the hearing aid and auditory evoked potentials recorded while the listener wears hearing aids. Acoustic analysis topics include the relationship between conventional probe microphone tests and probe microphone measurements using speech, appropriate procedures for such tests, and assessment of signal-processing effects on speech acoustics and recognition. Auditory evoked potential topics include an overview of physiologic measures of speech processing and the effect of hearing loss and hearing aids on cortical auditory evoked potential measurements in response to speech. Finally, the clinical utility of these procedures is discussed.

Acoustic Stimulation↗

PubMed2006

Effect of probe tube insertion depth on spectral measures of speech.

This study investigated how depth variations in the tip of the probe tube affected spectral measures of speech recorded in the external ear canal. Consonant-vowel nonsense syllables were recorded with a probe tube microphone system in 10 adult participants with normal middle ear function. Recordings were made with the probe tube tip placed 1 mm, 5 mm, and 10 mm beyond the medial tip of a custom earmold. The effect of probe depth was evaluated on spectral levels (one-third octave and one- twelfth octave band). Extending the probe tube 10 mm past the medial tip of the earmold gave the most accurate results, with relatively lower sound levels for either the 1-mm or 5-mm insertion depth. In general, the effect of insertion depth was minimal at frequencies below 3 to 4 kHz, although this varied with the specific phoneme and the width of the analysis bands. The authors found no significant difference between 1- and 5-mm insertion depths, suggesting that as long as the tip of the probe tube is sufficiently close to the tympanic membrane to capture the highest frequency of interest, it makes little difference if it is less than 5 mm beyond the earmold tip.

Acoustic Stimulation↗

PubMed2006

The neural representation of consonant-vowel transitions in adults who wear hearing AIDS.

Hearing aids help compensate for disorders of the ear by amplifying sound; however, their effectiveness also depends on the central auditory system's ability to represent and integrate spectral and temporal information delivered by the hearing aid. The authors report that the neural detection of time-varying acoustic cues contained in speech can be recorded in adult hearing aid users using the acoustic change complex (ACC). Seven adults (50-76 years) with mild to severe sensorineural hearing participated in the study. When presented with 2 identifiable consonant-vowel (CV) syllables ("shee" and "see"), the neural detection of CV transitions (as indicated by the presence of a P1-N1-P2 response) was different for each speech sound. More specifically, the latency of the evoked neural response coincided in time with the onset of the vowel, similar to the latency patterns the authors previously reported in normal-hearing listeners.

Aged↗

PubMed2005

Development and validation of the effectiveness of [corrected] auditory rehabilitation scale.

OBJECTIVE: To develop a new scale of hearing-related function and quality of life in patients with hearing aids that addresses overlooked concerns, such as hearing-aid comfort, convenience, and cosmetic appearance, that may influence hearing-aid adherence while maintaining brevity and sensitivity to clinical change. DESIGN: Prospective, multicenter instrument validation. SETTING: Four diverse sites in Washington State, including 2 private practices, 1 university setting, and 1 Veterans Affairs hospital. PATIENTS: Seventy-eight patients with hearing aids. INTERVENTIONS: We created 2 modules in the Effectiveness of Auditory Rehabilitation (EAR) scale. The first module (Inner EAR) covers intrinsic hearing issues such as hearing in quiet and hearing in noise and is administered both before and after treatment. The second module (Outer EAR) covers extrinsic (hearing-aid related) issues such as comfort, appearance, and convenience and is administered after hearing-aid fitting. MAIN OUTCOME MEASURES: Both scales were developed and validated in 3 stages. Stage 1 used a qualitative approach from multiple data sources to develop preliminary instruments. Stage 2 used approaches from classic test theory to reduce the number of items and psychometrically validate the instruments. Stage 3 examined the responsiveness or sensitivity to clinical change. RESULTS: A 10-item Inner EAR module and a 10-item Outer EAR module were created and validated. Internal consistency of individual domains (Cronbach alpha = 0.85 and 0.72, respectively) and test-retest reliability (intraclass correlation coefficients = 0.76 and 0.81, respectively) were excellent. Evidence of construct validity included concurrent validity with other hearing scales and global visual analog scales, discriminant validity with dizziness handicap, correlation with hearing-aid adherence, and confirmatory factor analyses. Both scales had strong evidence of responsiveness (sensitivity to change), with higher effect sizes and Guyatt responsiveness statistics than the 2 widely used hearing scales in this study. The scales took an average of 5 minutes to complete. CONCLUSIONS: The EAR scale is a valid and reliable measure of the effectiveness of amplification in the treatment of sensorineural hearing loss. It addresses the range of issues that are of importance to hearing-aid patients. The scales have excellent psychometric properties, are more responsive than several widely used hearing scales, and are minimally burdensome for patients to complete. The EAR may be a valuable outcome measure in future studies of both existing hearing aids and newer hearing-aid technologies, such as bone-anchored aids or middle ear implants.

Factor Analysis, Statistical↗

PubMed2005

Quantifying the effect of compression hearing aid release time on speech acoustics and intelligibility.

Compression hearing aids have the inherent, and often adjustable, feature of release time from compression. Research to date does not provide a consensus on how to choose or set release time. The current study had 2 purposes: (a) a comprehensive evaluation of the acoustic effects of release time for a single-channel compression system in quiet and (b) an evaluation of the relation between the acoustic changes and speech recognition. The release times under study were 12, 100, and 800 ms. All of the stimuli were VC syllables from the Nonsense Syllable Task spoken by a female talker. The stimuli were processed through a hearing aid simulator at 3 input levels. Two acoustic measures were made on individual syllables: the envelope-difference index and CV ratio. These measurements allowed for quantification of the short-term amplitude characteristics of the speech signal and the changes to these amplitude characteristics caused by compression. The acoustic analyses revealed statistically significant effects among the 3 release times. The size of the effect was dependent on characteristics of the phoneme. Twelve listeners with moderate sensorineural hearing loss were tested for their speech recognition for the same stimuli. Although release time for this single-channel, 3:1 compression ratio system did not directly predict overall intelligibility for these nonsense syllables in quiet, the acoustic measurements reflecting the changes due to release time were significant predictors of phoneme recognition. Increased temporal-envelope distortion was predictive of reduced recognition for some individual phonemes, which is consistent with previous research on the importance of relative amplitude as a cue to syllable recognition for some phonemes.

Adult↗

PubMed2005

Using multichannel wide-dynamic range compression in severely hearing-impaired listeners: effects on speech recognition and quality.

OBJECTIVE: The objective of this study was to compare speech recognition across a sampling of amplification choices available for listeners with severe loss. This includes conventional options (linear with peak clipping and linear with compression limiting) and newer strategies (multichannel wide-dynamic range compression [WDRC]) theorized to better accommodate reduced dynamic range. A second objective was to compare speech quality across the same conditions using a paired-comparison test. DESIGN: Participants were 13 adults with severe sensorineural hearing loss and a control group of seven adults with normal hearing. Test materials included consonant-vowel syllables (speech recognition) and sentences (speech quality). Four amplification conditions were included: peak clipping; compression limiting; two-channel WDRC; and three-channel WDRC, with overall audibility similar across conditions. In the WDRC conditions, the compression ratio was fixed at 3:1 in each channel. Consonant recognition was measured using a closed-set task, and speech quality was measured using a paired-comparison test. RESULTS: For the listeners with severe loss, recognition and preference were lower for a three-channel WDRC system than for a compression limiting system. Specific errors were consistent with poorer transmission of amplitude envelope information by the multichannel WDRC systems. CONCLUSIONS: Under some conditions, the benefit of fast-acting, multichannel WDRC systems relative to more linear amplification strategies may be reduced in listeners with severe loss. Performance decrements with these systems are consistent with consequences of broader auditory filters.

Acoustic Stimulation↗

PubMed2003

Effects of aging on auditory processing of speech.

The focus of this paper is on the effects of age on speech perception, with reference to pertinent psychoacoustic findings. The difficulties of older listeners are related to the well-known effects of high-frequency hearing loss on speech perception in quiet, and to temporal processing declines not predictable from the audiogram that account for reduced ability to listen in complex, noisy conditions. We also discuss issues of research interpretation; e.g. the need for researchers and clinicians to be alert to the frequent confound between degree of hearing loss and age. The implications of age-related changes in auditory speech processing for future practice and research are discussed relative to interactions between older individuals and their acoustic environments.

Age Factors↗

PubMed2003

Effects of decreased audibility produced by high-pass maskers in younger and older adults.

A recurring problem in aging research is separating the effects of age per se from the effects of high-frequency hearing loss. One approach is to present test stimuli in the presence of a high-pass masker to control confounding differences in high-frequency audibility across age groups. However, there is evidence that such maskers may affect older and younger listeners differently. In this study, pure-tone thresholds were measured for younger and older listeners in the presence of high-pass maskers. The age groups were carefully selected based on similar unmasked thresholds at each frequency. Thresholds were measured in quiet and in seven masker conditions. Both younger and older listeners showed increased threshold shift below the masker passband as the masker level increased. The degree of threshold shift was not greater for older versus younger listeners. Results suggest that high-pass maskers may be used to reduce high-frequency sensitivity differences between younger and older listeners without introducing differential masking effects.

Adult↗