Measurement with verification of stationary signals and noise in extremely quiet environments: measuring below the noise floor.

It can be problematic to measure stationary acoustic sound pressure level in any environment when the target level approaches or lies below the minimum measureable sound pressure level of the measurement system itself. This minimum measureable level, referred to as the inherent measurement system noise floor, is generally established by noise emission characteristics of measurement system components such as microphones, preamplifiers, and other system circuitry. In this paper, methods are presented and shown accurate measuring stationary levels within 20 dB above and below this system noise floor.

ABR obtained from time-efficient train stimuli for cisplatin ototoxicity monitoring.

Background: Nonbehavioral methods for identifying cisplatin ototoxicity are important for testing patients with cancer who become too tired or sick to provide a reliable response. The auditory brainstem response (ABR) is a nonbehavioral test that is sensitive to ototoxicity but can be time consuming to implement over a range of frequencies and/or levels. To address this issue, trains of stimuli were developed that offer reliable ABR testing over a range of tone-burst frequencies and levels at a time savings of 77% relative to tone-burst stimuli presented individually.

Differences in stress-related ratings between research center and home environments in dementia caregivers using ecological momentary assessment.

Background: Clinicians and researchers working with dementia caregivers typically assess caregiver stress in a clinic or research center, but caregivers' stress is rooted at home where they provide care. This study aimed to compare ratings of stress-related measures obtained in research settings and in the home using ecological momentary assessment (EMA).

Methods: EMA of 18 caregivers (mean age 66.

Assessing sleep architecture in dementia caregivers at home using an ambulatory polysomnographic system.

Findings from previous research assessing sleep quality in caregivers are inconsistent due to differences in sleep assessment methods. This study evaluated sleep in dementia caregivers using a comprehensive sleep assessment utilizing an ambulatory polysomnography (PSG) device. A total of 20 caregivers and 20 noncaregivers rated their perceived sleep quality, stress, and depressive symptoms; provided samples of cortisol and inflammatory biomarkers; and completed an objective sleep assessment using a portable PSG device.

Dynamic range considerations when designing PC sound card based audiometric systems to test human hearing.

An investigation into maximizing the dynamic range of a PC sound card based audiometric test system is presented. Two principle sound paths are characterized: a) the analog line input, and, b) internal waveform conversion from digital formats into analog signals. Each signal path's electrical performance and overall dynamic range is measured using audio harmonic distortion analysis and frequency spectrum analysis tools.

Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system.

Report contains the design overview and key performance measurements demonstrating the feasibility of generating and recording ambulatory visual stimulus evoked potentials using the previously reported custom Complementary and Alternative Medicine physiologic data collection and monitoring system, CAMAS. The methods used to generate visual stimuli on a PDA device and the design of an optical coupling device to convert the display to an electrical waveform which is recorded by the CAMAS base unit are presented. The optical sensor signal, synchronized to the visual stimulus emulates the brain's synchronized EEG signal input to CAMAS normally reviewed for the evoked potential response.

On the synthesis of multiple frequency tone burst stimuli for efficient high frequency auditory brainstem response.

The development and digital waveform synthesis of a multiple-frequency tone-burst (MFTB) stimulus is presented. The stimulus is designed to improve the efficiency of monitoring high-frequency auditory-brainstem-response (ABR) hearing thresholds. The pure-tone-based, fractional-octave-bandwidth MFTB supports frequency selective ABR audiometry with a bandwidth that falls between the conventional click and single-frequency tone-burst stimuli.

Second generation complementary and alternative medicine physiologic data collection and monitoring research platform.

Progress on our second generation portable system specifically designed to collect 24 hour ambulatory physiologic data from human subjects is reported. The upgraded system has more sensor flexibility and better performance and is smaller, lighter, and simpler to use than our previous version. The new system continues to support a wide variety of sensors found useful for complementary and alternative medicine (CAM) research and has been designed using a modular approach for future expansion of capabilities.

Instrumentation system upgrade supports mobile personalized healthcare delivery.

Clinicians and patients need mobile tools to detect ototoxic change early and prevent hearing loss. We report on the development of an upgrade of our existing desktop-based clinical-audiological instrumentation into a mobile instrument platform which efficiently supports personalized ototoxicity monitoring on the hospital wards as well as clinic by a trained clinician. Our new wireless-enabled system also serves as the instrumentation platform for the next phase of our work which is remote healthcare delivery with patient-guided at-home ototoxicity monitoring using an evidence-based individualized SRO protocol.

24 hour ambulatory research system supporting multiple physiologic sensors.

The design and development of a 24-hour ambulatory physiological data collection system is reported. The system was designed specifically to support the needs of investigators studying mind-body interventions but could be used for a variety of research needs. The system is novel in that it supports a wide variety of physiologic sensors with a relatively high sample rate, full data storage, and standalone run-time of greater than 24 hours.

Heart rate variability analysis of effect of nicotine using periodograms.

Heart rate variability (HRV) is frequently used to measure autonomic nervous system (ANS) activity. However, little is known about the mechanism underlying pharmacologically induced changes in HRV. Previous research has shown that nicotine exposure stimulates the ANS, mediating a wide spectrum of physiological and behavioral effects, including altered respiratory sinus arrhythmia and enhanced arousal and attention.

Computer-automated tinnitus assessment using patient control of stimulus parameters.

A need exists for a standardized tinnitus evaluation tool to measure "acoustic" parameters of tinnitus. An automated tinnitus evaluation system has been developed in this laboratory, consisting of a patient-controlled touch-screen computer monitor, main computer, and Programmable Auditory Laboratory 3000 (PAL 3000) (a custom-built signal conditioning module). The system obtains and records data from tinnitus patients, including hearing thresholds and the pitch and loudness of their tinnitus.

Comparison of manual and computer-automated procedures for tinnitus pitch-matching.

Clinical assessment of tinnitus usually includes pitch-matching between the tinnitus and a pure tone. Although such testing is performed routinely, response reliability has not been demonstrated yet. The present study continues a series of studies designed to develop automated methodology for quantifying tinnitus perceptual characteristics.

Use of auditory brainstem responses for the early detection of ototoxicity from aminoglycosides or chemotherapeutic drugs.

Effective objective HF (high-frequency) testing methodology provides for the early detection of ototoxic hearing loss because it typically progresses from high to low frequencies. Such early detection is considered necessary to prevent hearing loss from progressing into the frequency range important for understanding speech. Objective tests must be reliable, sensitive to hearing change, and time efficient.

Reliability of computer-automated hearing thresholds in cochlear-impaired listeners using ER-4B Canal Phone earphones.

This paper describes the second phase of a study to determine test-retest reliability of hearing thresholds using a computer-automated technique with ER-4B Canal Phone insert earphones. The first phase documented reliable hearing thresholds in 20 normal-hearing individuals. For this second phase, 20 individuals with cochlear hearing loss completed the same testing protocol as for phase one.

Comparison of ABR stimuli for the early detection of ototoxicity: conventional clicks compared with high frequency clicks and single frequency tonebursts.

Effective objective testing methodology is needed for early detection of the effects of ototoxicity on hearing in patients. The requirements for such testing include responses that are: 1) reliable across test sessions; 2) sensitive to ototoxic change ( > 8 kHz), and 3) recordable in a time-efficient manner. Auditory brainstem responses (ABR) appear well suited to this task however, conventional clicks stimulate primarily mid-frequencies (1-4 kHz) and high frequency tonebursts require too much time.