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PubMedDate not supplied

Implantable bone conduction hearing device: Audiant bone conductor. Update on our experiences.

An implantable hearing device has been developed and has undergone testing by animal experimentation and clinical trials in humans. Recently, the Food and Drug Administration has approved the use of this device in adults who are within the criteria of its utilization, mainly patients with conductive hearing impairments who have good inner ear reception and who are unable to benefit from surgical correction. This update describes observations and experiences we have had during the device's development and defines its limitations as well as its unique thrust into the future relief of hearing impairment. Clinical trials during the investigational period and engineering problems as well as progress are thoroughly discussed.

Adolescent↗
PubMed1985

The influence of masking on the ipsi- and contralateral brainstem evoked potential.

We have examined clinically and experimentally the masking effects of white noise in registering brainstem evoked potentials and determining the Jewett-wave V. We studied input-output functions as well as latency periods of evoked potentials with masking of non-stimulated contralateral ears in 18 children aged 5-14 years. When differences of 50 dB or more were found between stimulation and masking, the Jewett-wave V could be partially suppressed. Other changes observed included alterations in potential and phase, as well as shifts in the latency period of the potentials. The clinical importance of the measurements determined indicates that findings may be used in examining patients with unilateral sensory hearing impairments to formulate possible differential diagnoses.

Adolescent↗
PubMed1985

Effects of sympathetic stimulation on the round window compound action potential in the rat.

The effect on the ear of stimulating the sympathetic nervous system was studied in rats by recording the compound action potentials (N1N2) in response to 2 kHz tonebursts presented to anesthetized rats before, during, and after electrical stimulation of the superior cervical ganglion, and evaluating the changes in N1 latency which resulted. Stimulation of the superior cervical ganglion was found to cause an increase in the N1 latency which was more pronounced at low stimulus intensities (mean value 0.09 +/- 0.04 ms (S.E.) at 5 dB above threshold) than at moderate stimulation intensities (0.08 +/- 0.04 ms at 15 dB above threshold), with little change in latency occurring at the highest intensity tested (0.02 +/- 0.01 ms at approximately 25-30 dB above threshold). In addition, individual animals varied in their responses to stimulation of the superior cervical ganglion, with some animals evidencing a great change in the latency of the response (0.4 ms increase at 10 dB above threshold) and others showing very little change in latency. This variability could not be related to the condition of the animal at the time of observation of the response. In one of the twelve animals there was a slight decrease in latency as a result of sympathetic stimulation (0.07 ms at 5 dB above threshold), and although not studied systematically, low frequencies seemed to be affected more than high frequencies. Further, the change in the amplitude of N1 was not systematically related to sympathetic stimulation. After the administration of hexamethonium (which blocks transmission in autonomic ganglia) in three rats there was no effect on the latency of the N1 potential from sympathetic stimulation as recorded before sympathetic stimulation.

Animals↗
PubMed1982

Synesthetic perception and poetic metaphor.

To explore the role of cross-modal perception in the apprehension of synesthetic metaphors, subjects read 15 short lines from poetry, each of which contained a metaphor relating visual and auditory qualities; the subjects' task was to set the loudness of a 1000-Hz tone and the brightness of a white light to match the levels implied by each metaphor. The sound settings and light settings suggest that a cross-modal equivalence between loudness and brightness largely underlay the responses to the metaphors. This general cross-modal equivalence was characterized by some notable intersubject differences and was modified, in part, by certain metaphors that resisted complete equivalence. Even so, the metaphorically induced settings of loudness and brightness are mainly governed by a cross-modality matching function that is qualitatively like the relation found in people with visual-auditory synesthesia, and that is quantitatively like the function obtained in more traditional psychophysical studies.

Humans↗
PubMed2006

Amygdalohippocampal involvement in tinnitus and auditory memory.

CONCLUSION: The preliminary results suggest that in chronic unilateral tinnitus the contralateral amygdalohippocampal complex does seem to be involved in tinnitus perception of pure tones. OBJECTIVES: Functional neuroimaging studies have revealed that the hippocampus and amygdala are involved in tinnitus perception. The amygdala and hippocampus are supplied by the anterior choroidal artery. Selective amobarbital injections in the anterior choroidal artery result in a non-functional amygdalohippocampal area for 10 min. The aim of this study was to assess the influence of this procedure on tinnitus perception. PATIENTS AND METHODS: Amobarbital (80 mg in total) was injected selectively in two sessions in the left and right anterior choroidal artery in six male patients with tinnitus: four with unilateral tinnitus, two with bilateral tinnitus. Of the patients with unilateral tinnitus, three had right-sided tinnitus and one had left-sided tinnitus. The average age was 57.3 years (range 43-69). Average tinnitus duration was 5.3 years (range 1-10). The differences in visual analogue scale (VAS) scores before and after the amytal tests were analysed. RESULTS: Amytal injection ipsilateral to the side where the tinnitus was perceived resulted in a maximum of 30% tinnitus suppression, whereas amytal injection contralateral to the tinnitus side yielded a 60-70% tinnitus suppression in three patients with unilateral chronic tinnitus (>4 years). Only pure tone tinnitus was suppressed, white noise was not. Two patients with bilateral tinnitus had no suppression, irrespective of the tinnitus type. A third patient without clinical tinnitus suppression had tinnitus of more recent origin (1.5 years).

Adult↗
PubMed2000

Low-frequency acoustic modulations generated by the high-frequency portion of the cochlea, noninvasively recorded from the scalp of mice (Mus musculus).

Vocalizations often contain low-frequency modulations of the envelope of a high-frequency sound. The high-frequency portion of the cochlear nerve of mice (Mus musculus) generates a robust phase-locked response to these low-frequency modulations, and it can be easily recorded from the surface of the scalp. The cochlea is most sensitive to envelope modulation frequencies of approximately 500 to 2000 Hz. These responses have detection thresholds that are approximately 10 dB more sensitive than auditory brainstem responses, and they are very sharply tuned. These measurements may provide a nontraumatic means of repeatedly assessing cochlear functions involved in sound localization and perception of vocalizations.

Animals↗
PubMed1986

Neuroanatomy, neurophysiology, and central auditory assessment. Part I: Brain stem.

This paper is the first in a series of three that address neuroanatomical and neurophysiological aspects of central auditory assessment. The focus of this article is the "auditory" brain stem. Pictures of the auditory structures in the human brain stem in normal and pathological states are shown. Physiological evidence of neural coding of acoustic stimuli is discussed. Relationships between brain stem anatomy/physiology and clinical test results and their interpretation are highlighted.

Auditory Pathways↗
PubMed2004

[Implementation of habituation theory to pulsatile somato-sounds (tinnitus): the heart valve prosthesis sound model].

OBJECTIVES: To evaluate the habituation process to mechanical heart valve prosthesis sound as a model to understand the pulsatile tinnitus or somatosound perception changes. STUDY DESIGN: Transversal descriptive. PATIENTS: One hundred and fifty patients referred to a University Hospital for one or two mechanical heart valve implantation. OUTCOME MEASURES: Questionnaire sent by mail for prosthesis sound loudness and interference in quality of life evaluation. Detection of factors related to habituation process development. RESULTS: Eighty three percent of the patients perceived their prosthesis sound continuously, while only a 17% showed high levels of annoyance. No significative differences in prosthesis type and localization were described. Anxiety was the most important factor for loudness increase. The average of visual analogical scales on sound loudness and annoyance showed mild values (3.7 and 1.9 respectively). CONCLUSIONS: Extensive medical counselling or tinnitus retraining therapy (TRT) program for most severe cases, are proposed for pulsatile tinnitus management when etiological treatment cannot be available.

Adult↗
PubMed1990

A new version of duplex perception: evidence for phonetic and nonphonetic fusion.

In a series of experiments, a variant of duplex perception was investigated. In its original form, duplex perception is created by presenting an isolated transition to one ear and the remainder of the syllable, the standard base, to the other ear. Listeners hear a chirp at the ear receiving the isolated transition, and a full syllable at the ear receiving the base. The new version of duplex perception was created by presenting a third-formant transition in isolation to one ear and the same transition electronically mixed with the base to the other ear; the modified base now has all the information necessary for syllabic perception. With the new procedure, listeners reported hearing a chirp centered in the middle of their head and a syllable in the ear presented the modified base that was clearer than that produced by the isolated transition and standard base. They could also reliably choose the patterns that contained the additional transition in the base when attending to either the phonetic or nonphonetic sides of the duplex percept. In addition, when the fundamental frequency, onset time, and intensity of the isolated third-formant transition were varied relative to the base, the phonetic and nonphonetic (lateralization) percepts were differentially affected, although not always reliably. In general, nonphonetic fusion was more affected by large differences in these variables than was phonetic fusion. However, when two isolated third-formant transitions were presented dichotically, fusion and the resulting central location of the chirp failed markedly with relatively small differences in each variable. The results were discussed in terms of the role of fusion in the new version of duplex perception and the nature of the information that undergoes both phonetic and nonphonetic fusion.

Adult↗
PubMed2003

Cochlear compression: perceptual measures and implications for normal and impaired hearing.

This article provides a review of recent developments in our understanding of how cochlear nonlinearity affects sound perception and how a loss of the nonlinearity associated with cochlear hearing impairment changes the way sounds are perceived. The response of the healthy mammalian basilar membrane (BM) to sound is sharply tuned, highly nonlinear, and compressive. Damage to the outer hair cells (OHCs) results in changes to all three attributes: in the case of total OHC loss, the response of the BM becomes broadly tuned and linear. Many of the differences in auditory perception and performance between normal-hearing and hearing-impaired listeners can be explained in terms of these changes in BM response. Effects that can be accounted for in this way include poorer audiometric thresholds, loudness recruitment, reduced frequency selectivity, and changes in apparent temporal processing. All these effects can influence the ability of hearing-impaired listeners to perceive speech, especially in complex acoustic backgrounds. A number of behavioral methods have been proposed to estimate cochlear nonlinearity in individual listeners. By separating the effects of cochlear nonlinearity from other aspects of hearing impairment, such methods may contribute towards identifying the different physiological mechanisms responsible for hearing loss in individual patients. This in turn may lead to more accurate diagnoses and more effective hearing-aid fitting for individual patients. A remaining challenge is to devise a behavioral measure that is sufficiently accurate and efficient to be used in a clinical setting.

Acoustic Stimulation↗
PubMed1990

Harmonic and melodic octave templates.

For normal-hearing adult listeners, two simultaneous pure tones with a frequency ratio close to 2/1 may perceptually fuse into a single sound, which shows that such listeners are sensitive to "octave harmony." Many adult listeners are also able to consistently adjust two successive pure tones "one octave apart," which shows that they possess melodic octave templates. According to Terhardt [J. Acoust. Soc. Am. 55, 1061-1069 (1974)], melodic octave templates and the perception of octave harmony originate from a common learning process taking place in early life. In the two experiments reported here, subjects performed repeated octave adjustments for pairs of simultaneous and successive tone bursts. Both tones were presented monaurally, at 45 or 65 dB SPL. The frequency of the lower tone (fref) was an independent variable, while the frequency of the higher tone was adjustable within a 500-cent range. In some conditions, when the two tones were presented simultaneously, they were sinusoidally frequency modulated in a coherent manner, at a rate of 2 or 4 Hz; the aim of this frequency modulation was to force the subjects to adopt a synthetic listening strategy, i.e., to base their adjustments on perceived harmony. For fref values ranging from 270-2000 Hz, subjects performed consistent adjustments when the tones were presented successively: fref had little effect on the adjustments' variability. However, in the same frequency range, the variability of the harmonic adjustments markedly increased with fref; for the highest fref values, it was much greater than the variability of the melodic adjustments. The results suggest that, in adult listeners, the perception of octave harmony disappears at frequencies for which melodic octaves are still accurately perceived.

Adult↗
PubMed1992

Intertrial interval and sequential effects in magnitude scaling.

The intertrial interval (ITI) was varied within subjects in magnitude estimation and cross-modality matching experiments. Fits of a recently proposed time series regression model show that the influence of the previous stimulus intensity on the current response decreases when the ITI is increased. The results can be interpreted as showing that an assimilative or additive perceptual or memory effect decreases with an increase in ITI. Fits of an earlier model, on the other hand, suggest that the influence of the previous stimulus intensity increases with an increase in ITI, which is counter to expectations. The new regression model (a) provides a simple explanation for the counterintuitive results obtained with the earlier model, (b) shows that assimilation in perception or memory can appear as contrast, and (c) reduces to a simpler model for longer ITIs.

Adult↗
PubMed1997

Managing tinnitus: a comparison of different approaches to tinnitus management training.

A series of studies examining the interaction between the characteristics of individual tinnitus sufferers and the effectiveness of the methods used to assist them has been conducted. The first of these studies provided a baseline description of 96 people with tinnitus, according to a range of audiological and psychological variables. In the present paper four differing tinnitus management programmes are described and the related changes in tinnitus perception reported three months after tinnitus management training. For the majority of subjects, the tinnitus was less annoying and less distressing three months after attending tinnitus management training. However, the majority of subjects reported no change in tinnitus loudness, or tinnitus awareness and no change in their tinnitus coping ability. Subjects receiving low level white noise stimulation reported greater improvement in tinnitus coping ability than subjects who received information and relaxation training, although there was no associated improvement in tinnitus awareness. Subjects' beliefs about tinnitus and preferred coping style may have influenced the reported benefit or otherwise of the differing tinnitus management techniques.

Acoustic Stimulation↗
PubMed1997

Intracellular response properties of units in the dorsal cochlear nucleus of unanesthetized decerebrate gerbil.

Intracellular recording experiments on the dorsal cochlear nuclei of unanesthetized decerebrate gerbils were conducted. Acceptable recordings were those in which resting potentials were -50 mV or less and action potentials (APs) were > or = 40 mV. Responses to short-duration tones and noise, and to current pulses delivered via recording electrodes, were acquired. Units were classified according to the response map scheme (types I-IV). Ninety-two acceptable recordings were made. Most units had simple APs (simple-spiking units); nine units had both simple and complex APs, which are bursts of spikes embedded on slow, transient depolarizations (complex-spiking units). Of 83 simple-spiking units, 46 were classified as follows: type I/III (9 units), type II (9 units), type III (25 units), type IV (2 units), and type IV-T (1 unit). One complex-spiking unit was classifiable (a type III unit); six were unclassifiable because of weak acoustic responses. Classifying 39 other simple-spiking units and 2 complex-spiking units was impossible, because they were either injured or lost before sufficient data were acquired. Many simple-spiking units showed depolarization or hyperpolarization (approximately 5-10 mV) during acoustic stimulation; some were hyperpolarized during the stimulus-off period. Type I/III units were not hyperpolarized during off-best-frequency (off-BF) stimulation. In contrast, many type II units were hyperpolarized by off-BF frequencies, suggesting that they received strong inhibitory sideband inputs. When inhibited, some type III units were hyperpolarized. Type IV units were hyperpolarized during inhibition even at low levels (<60 dB SPL); sustained depolarizations occurred only at higher levels, suggesting that they receive strong inhibitory and weak excitatory inputs. Several intracellular response properties were statistically different from those of extracellularly recorded units. Intracellularly recorded type II units had higher thresholds and lower maximum BF-driven and noise-driven rates than their extracellularly recorded counterparts. Type I/III units recorded intracellularly had lower maximum BF-driven rates. Type III units recorded intracellularly had higher maximum noise rates compared with those recorded extracellularly. Weaker acoustic responses most likely result from membrane disruption, but heightened responses may be related to weakened chloride-channel-dependent inhibition due to altered driving forces resulting from KCl leakage. Firing rates of simple-spiking units increased monotonically with increasing levels of depolarizing current pulses. In contrast, many complex-spiking units responded nonmonotonically to depolarizing current injection. The monotonic rate-versus-current curves and the nonmonotonic rate-versus-sound level curves of type IV and III units suggest that the acoustic behavior is the result of extrinsic inhibitory inputs and not due solely to intrinsic membrane properties.

Animals↗
PubMed1997

Acceptability for temporal modification of consecutive segments in isolated words.

Perceptual sensitivity to temporal modification in two consecutive speech segments was measured in word contexts to explore the following two questions: (1) whether there is an interaction between multiple segmental durations, and (2) what aspect of the stimulus context determines the perceptually salient temporal markers? Experiment 1 obtained acceptability ratings for words with temporal modifications. The results showed that the compensatory change in duration of a vowel (V) and its adjacent consonant (C) is not perceptually so salient as expected for the simultaneous modifications in the two segments. This finding suggests the presence of a time perception range wider than a single segment (V or C). The results of experiment 1 also showed that rating scores for compensatory modification between V and C do not depend on the temporal order of modified pairs (VC or CV), but rather on the loudness difference between V and C; the acceptability decreased when the loudness difference between V and C became high. This suggests that perceptually salient markers locate around major jumps in loudness. The second finding, the dependence on the loudness jump, was replicated in experiment 2, which utilized a detection task for temporal modifications on nonspeech stimuli modeling the time-loudness features of the speech stimuli. Experiment 3 further investigated the influence of the temporal order of V and C by utilizing the detection task for the speech stimuli instead of the acceptability ratings.

Humans↗
PubMed2003

An investigation of input level range for the nucleus 24 cochlear implant system: speech perception performance, program preference, and loudness comfort ratings.

OBJECTIVE: Cochlear implant recipients often have limited access to lower level speech sounds. In this study we evaluated the effects of varying the input range characteristics of the Nucleus 24 cochlear implant system on recognition of vowels, consonants, and sentences in noise and on listening in everyday life. DESIGN: Twelve subjects participated in the study that was divided into two parts. In Part 1 subjects used speech processor (Nucleus 24 SPrint trade mark ) programs adjusted for three input sensitivity settings: a standard or default microphone sensitivity setting (MS 8), a setting that increased the input sensitivity by 10.5 dB (MS 15), and the same setting that increased input sensitivity but also incorporated the automatic sensitivity control (ASC; i.e., MS 15A) that is designed to reduce the loudness of noise. The default instantaneous input dynamic range (IIDR) of 30 dB was used in these programs (i.e., base level of 4; BL 4). Subjects were tested using each sensitivity program with vowels and consonants presented at very low to casual conversational levels of 40 dB SPL and 55 dB SPL, respectively. They were also tested with sentences presented at a raised level of 65 dB SPL in multi-talker babble at individually determined signal to noise ratios. In addition, subjects were given experience outside of the laboratory for several weeks. They were asked to complete a questionnaire where they compared the programs in different listening situations as well as the loudness of environmental sounds, and state the setting they preferred overall. In Part 2 of the study, subjects used two programs. The first program was their preferred sensitivity program from Part 1 that had an IIDR of 30 dB (BL 4). Seven subjects used MS 8 and four used MS 15, and one used the noise reduction program MS 15A. The second program used the same microphone sensitivity but had the IIDR extended by an additional 8 to 10 dB (BL 1/0). These two programs were evaluated similarly in the speech laboratory and with take-home experience as in Part 1. RESULTS PART 1: Increasing the microphone input sensitivity by 10.5 dB (from MS 8 to MS 15) significantly improved the perception of vowels and consonants at 40 and 55 dB SPL. The group mean improvement in vowel scores was 25 percentage points at 40 dB SPL and 4 percentage points at 55 dB SPL. The group mean improvement for consonants was 23 percentage points at 40 dB SPL and 11 percentage points at 55 dB SPL. Increased input sensitivity did not significantly reduce the perception of sentences presented at 65 dB SPL in babble despite the fact that speech peaks were then within the compressed range above the SPrint processor's automatic gain control (AGC) knee-point. Although there was a demonstrable advantage for perception of low-level speech with the higher input sensitivity (MS 15 and 15A), seven of the 12 subjects preferred MS 8, four preferred MS 15 or 15A, and one had no preference overall. Approximately half the subjects preferred MS 8 across the 18 listening situations, whereas an average of two subjects preferred MS 15 or 15A. The increased microphone sensitivity of MS 15 substantially increased the loudness of environmental sounds. However, use of the ASC noise reduction setting with MS 15 reduced the loudness of environmental sounds to equal or below that for MS 8. RESULTS PART 2: The increased instantaneous input range gave some improvement (8 to 9 percentage points for the 40 dB SPL presentation level) in the perception of consonants. There was no statistically significant increase in vowel scores. Mean scores for sentences presented at 65 dB SPL in babble were significantly lower (5 percentage points) for the increased IIDR setting. Subjects had no preference for the increased IIDR over the default. The IIDR setting had no effect on the loudness of environmental sounds. CONCLUSIONS: Given the fact that individuals differ in threshold (T) and comfort (C) levels for electrical stimulation, and preferred microphone sensitivity, volume control, and noise-reduction settings, it is essential for the clinicid recipient to determine what combination is best for the individual over several sessions. The results of this study clearly show the advantage of using higher microphone sensitivity settings than the default MS 8 to provide better speech recognition for low-level stimuli. However, it was also necessary to adjust other parameters such as map C levels, automatic sensitivity control and base level, to optimize loudness comfort in the diversity of listening situations an individual encounters in everyday life.

Auditory Threshold↗
PubMed1986

The effects of low-pass filtering and random splicing on the perception of speech.

In this paper the results are presented of an auditory description of 32 nonmanipulated, low-pass-filtered, and random-spliced speech samples. The description consisted of the ratings by three raters on 24 speech scales. The aim of this study was to establish the effects of the manipulations on the perception of speech. Insight into this question was gained by examining the reliability of, and the correlations between, the ratings in the three conditions, and by considering the outcomes of a number of t tests. It appeared that, after filtering, in addition to prosodic features, a number of voice quality characteristics remain present in the signal; articulatory information is eliminated. After splicing, not only voice quality features but also some articulatory and prosodic information remain present. Moreover, the study revealed that both content-masking techniques bring about systematic biases in the perception. These findings are relevant to emotion and personality research in which low-pass filtering and random splicing are used as masking techniques.

Humans↗
PubMed2001

When sound affects vision: effects of auditory grouping on visual motion perception.

Two identical visual targets moving across each other can be perceived either to bounce off or to stream through each other. A brief sound at the moment the targets coincide biases perception toward bouncing. We found that this bounce-inducing effect was attenuated when other identical sounds (auditory flankers) were presented 300 ms before and after the simultaneous sound. The attenuation occurred only when the simultaneous sound and auditory flankers had similar acoustic characteristics and the simultaneous sound was not salient. These results suggest that there is an aspect of auditory-grouping (saliency-assigning) processes that is context-sensitive and can be utilized by the visual system for solving ambiguity. Furthermore, control experiments revealed that such auditory context did not affect the perceptual qualities of the simultaneous sound. Because the attenuation effect is not manifest in the perception of acoustic characteristics of individual sound elements, we conclude that it is a genuine cross-modal effect.

Acoustic Stimulation↗