Development and validation of the Speech Reception in Noise (SPRINT) Test.

Since 1992, the Speech Recognition in Noise Test, or SPRINT, has been the standard speech-in-noise test for assessing auditory fitness-for-duty of US Army Soldiers with hearing loss. The original SPRINT test consisted of 200 monosyllabic words presented at a Signal-to-Noise Ratio (SNR) of +9 dB in the presence of a six-talker babble noise. Normative data for the test was collected on 319 hearing impaired Soldiers, and a procedure for making recommendations about the disposition of military personnel on the basis of their SPRINT score and their years of experience was developed and implemented as part of US Army policy.

Benefits of Nonlinear Frequency Compression in Adult Hearing Aid Users.

Background: Frequency-lowering (FL) algorithms are an alternative method of providing access to high-frequency speech cues. There is currently a lack of independent research addressing: (1) what functional, measureable benefits FL provides; (2) which, if any, FL algorithm provides the maximum benefit, (3) how to clinically program algorithms, and (4) how to verify algorithm settings.

Purpose: Two experiments were included in this study.

Assessment of auditory spatial awareness in complex listening environments.

In the real world, listeners often need to track multiple simultaneous sources in order to maintain awareness of the relevant sounds in their environments. Thus, there is reason to believe that simple single source sound localization tasks may not accurately capture the impact that a listening device such as a hearing aid might have on a listener's level of auditory awareness. In this experiment, 10 normal hearing listeners and 20 hearing impaired listeners were tested in a task that required them to identify and localize sound sources in three different listening tasks of increasing complexity: a single-source localization task, where listeners identified and localized a single sound source presented in isolation; an added source task, where listeners identified and localized a source that was added to an existing auditory scene, and a remove source task, where listeners identified and localized a source that was removed from an existing auditory scene.

Ear asymmetries and asymmetric directional microphone hearing aid fittings.

Purpose: To determine whether an asymmetry between ears for speech understanding in noise was related to performance with, or preference for, 1 of 2 asymmetric microphone fittings in which omnidirectional processing was provided to 1 ear and directional processing to the other.

Method: Twenty-eight adults with symmetric sensorineural hearing impairment were recruited from the clinic population. Sixteen individuals had symmetric hearing-in-noise ability between their right and left ears, and 12 participants had an asymmetry for speech understanding in noise between ears.

Evaluation of a "direct-comparison" approach to automatic switching in omnidirectional/directional hearing aids.

Background: Hearing aids today often provide both directional (DIR) and omnidirectional (OMNI) processing options with the currently active mode selected automatically by the device. The most common approach to automatic switching involves "acoustic scene analysis" where estimates of various acoustic properties of the listening environment (e.g.

An objective measure for selecting microphone modes in OMNI/DIR hearing aid circuits.

Objectives: Studies have shown that listener preferences for omnidirectional (OMNI) or directional (DIR) processing in hearing aids depend largely on the characteristics of the listening environment, including the relative locations of the listener, signal sources, and noise sources; and whether reverberation is present. Many modern hearing aids incorporate algorithms to switch automatically between microphone modes based on an analysis of the acoustic environment. Little work has been done, however, to evaluate these devices with respect to user preferences, or to compare the outputs of different signal processing algorithms directly to make informed choices between the different microphone modes.

The robustness of hearing aid microphone preferences in everyday listening environments.

Automatic directionality algorithms currently implemented in hearing aids assume that hearing-impaired persons with similar hearing losses will prefer the same microphone processing mode in a specific everyday listening environment. The purpose of this study was to evaluate the robustness of microphone preferences in everyday listening. Two hearing-impaired persons made microphone preference judgments (omnidirectional preferred, directional preferred, no preference) in a variety of everyday listening situations.

Intelligibility of speech in noise at high presentation levels: effects of hearing loss and frequency region.

These experiments examined how high presentation levels influence speech recognition for high- and low-frequency stimuli in noise. Normally hearing (NH) and hearing-impaired (HI) listeners were tested. In Experiment 1, high- and low-frequency bandwidths yielding 70%-correct word recognition in quiet were determined at levels associated with broadband speech at 75 dB SPL.

Field evaluation of an asymmetric directional microphone fitting.

Laboratory evidence suggests that an asymmetric microphone fitting (omnidirectional processing in one ear and directional processing in the other) can provide a directional advantage in background noise that is as great, or nearly as great, as that provided by binaural directional processing (Bentler et al, 2004). The present study investigated whether the potential benefit of an asymmetric fitting observed in the laboratory extends to real-life listening. Specifically, ease of listening was compared across a variety of real-life listening situations for asymmetric microphone fittings and bilateral omnidirectional processing.

Effect of signal-to-noise ratio on directional microphone benefit and preference.

This study examined speech intelligibility and preferences for omnidirectional and directional microphone hearing aid processing across a range of signal-to-noise ratios (SNRs). A primary motivation for the study was to determine whether SNR might be used to represent distance between talker and listener in automatic directionality algorithms based on scene analysis. Participants were current hearing aid users who either had experience with omnidirectional microphone hearing aids only or with manually switchable omnidirectional/directional hearing aids.

Predicting hearing aid microphone preference in everyday listening.

Seventeen hearing-impaired adults were fit with omnidirectional/directional hearing aids, which they wore during a four-week trial. For each listening situation encountered in daily living during a total of seven days, participants selected the preferred microphone mode and described the listening situation in terms of five environmental variables, using a paper and pencil form. Results indicated that hearing-impaired adults typically spend the majority of their active listening time in situations with background noise present and surrounding the listener, and the signal source located in front and relatively near.

Relationship between laboratory measures of directional advantage and everyday success with directional microphone hearing aids.

The improvement in speech recognition in noise obtained with directional microphones compared to omnidirectional microphones is referred to as the directional advantage. Laboratory studies have revealed substantial differences in the magnitude of the directional advantage across hearing-impaired listeners. This investigation examined whether persons who were successful users of directional microphone hearing aids in everyday living tended to obtain a larger directional advantage in the test booth than persons who were unsuccessful users.

Identifying dead regions in the cochlea: psychophysical tuning curves and tone detection in threshold-equalizing noise.

Objective: Recent studies indicate that high-frequency amplification may provide little benefit for listeners with moderate-to-severe high-frequency hearing loss, and may even reduce speech recognition. Moore and colleagues have proposed a direct link between this lack of benefit and the presence of regions of nonfunctioning inner hair cells (dead regions) in the basal cochlea and have suggested that psychophysical tuning curves (PTCs) and tone detection thresholds in threshold-equalizing noise (TEN) are psychoacoustic measures that allow detection of dead regions ([Moore, Huss, Vickers, Glasberg, & Alcántara, 2000]; [Vickers, Moore, & Baer, 2001]). The experiments reported here examine the consistency of TEN and PTC tasks in identifying dead regions in listeners with high-frequency hearing loss.

Performance of custom-fit versus fixed-format hearing aids for precipitously sloping high-frequency hearing loss.

This study compared the real-ear response provided by custom-fit hearing aids to the closest matching fixed-format disposable hearing aids in patients with precipitous high-frequency hearing loss. Laboratory and field measures of aided performance were obtained to compare patient performance with the custom-fit and fixed-format hearing aids. In addition, coupler versus real-ear response differences were compared for the two hearing aid types.

Influence of environmental factors on hearing aid microphone preference.

The purpose of this study was to identify characteristics of everyday listening situations that influence user preferences for omnidirectional versus directional hearing aid microphones. Eleven experienced hearing aid users were fitted with digital hearing aids featuring switchable omnidirectional (OMNI) and adaptive-directional (DIR) modes (programs). For 6 weeks, their task was to identify and describe at least one listening situation each day in which one program performed better than the other using a checklist daily journal format.

Performance of directional microphone hearing aids in everyday life.

This study explored the use patterns and benefits of directional microphone technology in real-world situations experienced by patients who had been fitted with switchable omnidirectional/directional hearing aids. Telephone interviews and paper-and-pencil questionnaires were used to assess perceived performance with each microphone type in a variety of listening situations. Patients who used their hearing aids regularly and switched between the two microphone configurations reported using the directional mode, on average, about one-quarter of the time.

A Clinical Trial of the ReSound BT2 Personal Hearing System.

The Food and Drug Administration requires that hearing aid manufacturers substantiate benefit claims in advertising with clinical research. Recently, Walden (1997) described a model protocol that might be used to assess hearing aid benefit in manufacturer-sponsored clinical trials. The Walter Reed protocol includes laboratory measures of speech recognition ability using the Continuous Speech Test (CST, Cox, Alexander, & Gilmore, 1987; Cox, Alexander, Gilmore, & Pusakulick, 1988) and the scales and subscales of the Profile of Hearing Aid Benefit (PHAB, Cox & Gilmore, 1990) to assess user benefit in four prototype listening environments.