A binaural beat constructed from a noise (L).

The binaural beat has been used for over 100 years as a stimulus for generating the percept of motion. Classically the beat consists of a pure tone at one ear (e.g.

Level discrimination of speech sounds by hearing-impaired individuals with and without hearing amplification.

Objectives: The current study was designed to see how hearing-impaired individuals judge level differences between speech sounds with and without hearing amplification. It was hypothesized that hearing aid compression should adversely affect the user's ability to judge level differences.

Design: Thirty-eight hearing-impaired participants performed an adaptive tracking procedure to determine their level-discrimination thresholds for different word and sentence tokens, as well as speech-spectrum noise, with and without their hearing aids.

Human auditory cortical responses to pitch and to pitch strength.

Pitch is a fundamental auditory sensation, underlying both music and speech perception. This study was designed to explore pitch coding in human auditory cortex by testing whether activity in pitch-responsive regions covaries as a function of pitch salience (pitch strength). A psychophysical paradigm was used to confirm three levels of pitch salience for two different pitch-evoking stimuli.

Making sense of listening: the IMAP test battery.

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the abilities to extract and use the information encoded in the auditory signal. We refer to these as listening skills (or auditory processing AP).

Grommets (ventilation tubes) for hearing loss associated with otitis media with effusion in children.

Background: Otitis media with effusion (OME; 'glue ear') is common in childhood and surgical treatment with grommets (ventilation tubes) is widespread but controversial.

Objectives: To assess the effectiveness of grommet insertion compared with myringotomy or non-surgical treatment in children with OME.

Search Strategy: We searched the Cochrane ENT Disorders Group Trials Register, other electronic databases and additional sources for published and unpublished trials (most recent search: 22 March 2010).

Reducing the effects of background noise during auditory functional magnetic resonance imaging of speech processing: qualitative and quantitative comparisons between two image acquisition schemes and noise cancellation.

Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz.

Method: Speech and narrowband noise were presented at a low sound level to 8 listeners during fMRI using 2 common scanning protocols: short ("continuous") and long ("sparse") temporal schemes.

Evidence for opponent-channel coding of interaural time differences in human auditory cortex.

In humans, horizontal sound localization of low-frequency sounds is mainly based on interaural time differences (ITDs). Traditionally, it was assumed that ITDs are converted into a topographic (or rate-place) code, supported by an array of neurons with parametric tuning to ITDs within the behaviorally relevant range. Although this topographic model has been confirmed in owls, its applicability to mammals has been challenged by recent physiological results suggesting that, at least in small-headed species, ITDs are represented by a nontopographic population rate code, which involves only two opponent (left and right) channels, broadly tuned to ITDs from the two auditory hemifields.

The role of segmentation difficulties in speech-in-speech understanding in older and hearing-impaired adults.

Older people often complain of difficulties in understanding speech in noisy circumstances. The current study tested the hypothesis that problems segmenting speech may contribute to these difficulties. Segmentation ability was measured in young normal-hearing, older normal-hearing and older hearing-impaired listeners.

Evidence for early specialized processing of speech formant information in anterior and posterior human auditory cortex.

Many speech sounds, such as vowels, exhibit a characteristic pattern of spectral peaks, referred to as formants, the frequency positions of which depend both on the phonological identity of the sound (e.g. vowel type) and on the vocal-tract length of the speaker.

Location of cells giving phase-locked responses to pure tones in the primary auditory cortex.

Phase-locked responses to pure tones have previously been described in the primary auditory cortex (AI) of the guinea pig. They are interesting because they show that some cells may use a temporal code for representing sounds of 60-300 Hz rather than the rate or place mechanisms used over most of AI. Our previous study had shown that the phase-locked responses were grouped together, but it was not clear whether they were in separate minicolumns or a larger macrocolumn.

Listening to urban soundscapes: Physiological validity of perceptual dimensions.

Predominantly, the impact of environmental noise is measured using sound level, ignoring the influence of other factors on subjective experience. The present study tested physiological responses to natural urban soundscapes, using functional magnetic resonance imaging and vector cardiogram. City-based recordings were matched in overall sound level (71 decibel A-weighted scale), but differed on ratings of pleasantness and vibrancy.

Auditory and visual orienting responses in listeners with and without hearing-impairment.

Head movements are intimately involved in sound localization and may provide information that could aid an impaired auditory system. Using an infrared camera system, head position and orientation was measured for 17 normal-hearing and 14 hearing-impaired listeners seated at the center of a ring of loudspeakers. Listeners were asked to orient their heads as quickly as was comfortable toward a sequence of visual targets, or were blindfolded and asked to orient toward a sequence of loudspeakers playing a short sentence.

Planar localisation analyses: a novel application of a centre of mass approach.

Sound localisation is one of the key roles for listening, and measuring localisation performance is a mainstay of the hearing research laboratory. Such measurements may consider both accuracy and, for incorrect trials, the size of the error. In terms of error analysis, localisation studies have frequently used general purpose univariate techniques in conjunction with either mean signed or unsigned error measurements.

The time course of binaural masking in the inferior colliculus of guinea pig does not account for binaural sluggishness.

Psychophysical studies show a slower response to changes in the specifically binaural input than to changes in the monaural input (binaural sluggishness). However, there is disagreement about the time course. Tracking changes in a target yields fast time constants, while detecting a constant target against a varying background yields the slowest.

Forward masking estimated by signal detection theory analysis of neuronal responses in primary auditory cortex.

Psychophysical forward masking is an increase in threshold of detection of a sound (probe) when it is preceded by another sound (masker). This is reminiscent of the reduction in neuronal responses to a sound following prior stimulation. Studies in the auditory nerve and cochlear nucleus using signal detection theory techniques to derive neuronal thresholds showed that in centrally projecting neurons, increases in masked thresholds were significantly smaller than the changes measured psychophysically.

The effect of stimulus context on pitch representations in the human auditory cortex.

Neuroimaging studies of pitch coding seek to identify pitch-related responses separate from responses to other properties of the stimulus, such as its energy onset, and other general aspects of the listening context. The current study reports the first attempt to evaluate these modulatory influences using functional magnetic resonance imaging (fMRI) measures of cortical pitch representations. Stimulus context was manipulated using a 'classical stimulation paradigm' (whereby successive pitch stimuli were separated by gaps of silence) and a 'continuous stimulation paradigm' (whereby successive pitch stimuli were interspersed with noise to maintain a stable envelope).

The effect of hearing-aid compression on judgments of relative distance.

The overall level of a sound is an important auditory cue to distance in rooms, but this cue might be affected adversely by the amplitude compression found in most modern hearing aids because this explicitly changes levels. This prediction was tested using a synthetic-distance design to measure the just-noticeable difference (JND) in distance from distances of 2 or 5 m. Twenty-six aided listeners participated.

Informational masking in young and elderly listeners for speech masked by simultaneous speech and noise.

Three experiments measured the effects of age on informational masking of speech by competing speech. The experiments were designed to minimize the energetic contributions of the competing speech so that informational masking could be measured with no large corrections for energetic masking. Experiment 1 used a "speech-in-speech-in-noise" design, in which the competing speech was presented in noise at a signal-to-noise ratio (SNR) of -4 dB.

Examining the role of frequency specificity in the enhancement and suppression of human cortical activity by auditory selective attention.

This study examined the neural basis of auditory selective attention using functional magnetic resonance imaging. The main hypothesis stated that attending to a particular sound frequency would significantly enhance the neural response within those tonotopic regions of the auditory cortex sensitive to that frequency. To test this prediction, low- and high-frequency sound sequences were interleaved to produce two concurrent auditory streams.

Auditory event-related potentials (ERPs) in audiovisual speech perception.

Purpose: It has recently been reported (e.g., V.

The mechanisms of tinnitus: perspectives from human functional neuroimaging.

In this review, we highlight the contribution of advances in human neuroimaging to the current understanding of central mechanisms underpinning tinnitus and explain how interpretations of neuroimaging data have been guided by animal models. The primary motivation for studying the neural substrates of tinnitus in humans has been to demonstrate objectively its representation in the central auditory system and to develop a better understanding of its diverse pathophysiology and of the functional interplay between sensory, cognitive and affective systems. The ultimate goal of neuroimaging is to identify subtypes of tinnitus in order to better inform treatment strategies.

Semi-automatic identification of independent components representing EEG artifact.

Objective: Independent component analysis (ICA) can disentangle multi-channel electroencephalogram (EEG) signals into a number of artifacts and brain-related signals. However, the identification and interpretation of independent components is time-consuming and involves subjective decision making. We developed and evaluated a semi-automatic tool designed for clustering independent components from different subjects and/or EEG recordings.

Compatibility of a magnetic position tracker with a cochlear implant system.

Objectives: The aim of this study was to reveal possible interspersion of a magnetic position tracking device into a cochlear implant system, which could lead to harmful signals on the implanted electrode.

Design: Signals at the output of the speech processor's compression stage and at the implant's electrode were recorded and analyzed for unwanted distortion or corrupted pulses related to the presence of the magnetic tracking device.

Results: No systematic impact of a Polhemus Liberty Latus magnetic tracking system on the output signals of an Advanced Bionics HiRes90k cochlear implant and Platinum Series speech processor was found.

Binaural sluggishness precludes temporal pitch processing based on envelope cues in conditions of binaural unmasking.

Binaural sluggishness refers to the binaural system's inability to follow fast changes in the interaural configuration of the incoming sound stream. Several studies have measured binaural sluggishness by measuring signal detection in conditions of binaural unmasking when the interaural configuration of the masker is changed over time. However, it has been shown that, in conditions of binaural unmasking, binaural sluggishness also affects the perception of temporal changes in the properties of the signal (i.