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PubMed2003

Tinnitus loudness matchings in relation to annoyance and grading of severity.

OBJECTIVE: To measure and compare different parameters of tinnitus loudness obtained via matching and to investigate their associations with self-reported severity of tinnitus. METHODS: From the audiology department 18 patients with unilateral tinnitus of sensorineural origin were selected. They underwent pure-tone audiometry, and in a matching paradigm their tinnitus pitch was estimated. Loudness was assessed at tinnitus frequency and at the frequency of best hearing and both were expressed in sensation level (SL) and hearing level (HL). Moreover, minimal masking level (MML) with white noise was assessed as well as thresholds for the tinnitus tone and a comparison tone in the contralateral ear when tinnitus was masked. RESULTS: Annoyance and grading of severity were associated with measures of loudness expressed in HL, MML, and pure-tone audiometry. Loudness in SL was not associated with self-reported severity. Tinnitus loudness, matched at the frequency of best hearing instead of the tinnitus frequency, appears to be less dependent on HL, while still being associated with distress and grading of severity. CONCLUSION: Severity of tinnitus is related to hearing thresholds, and loudness in SL provides little clinically useful information.

Auditory Threshold↗
PubMed1995

Critical bandwidth determined by masking in the presence of two narrow-band noises.

In this experiment, the critical band (CB)-widths were measured using two narrow-band noises (NBNs) with steep cut-off slopes as a masker, varying their spectral level and center-frequency. The following results were obtained: (i) The CB-widths at all center-frequencies were narrower than the classical CB-widths estimated by Zwicker et al [J Acoust Soc Am 29:548-557 (1957)], and decreased continuously toward the lower frequency at the center-frequencies below 500 Hz, though Zwicker's data were constant in the same range. These results barely coincided with the frequency dependence of the equivalent rectangular bandwidth (ERB) which was estimated from the shape of the auditory filter measured directly. (ii) Level dependence of masking noise in CB was constant beyond 20 dB of the masked threshold. This depends on the use of NBN as a masker. (iii) The CB was influenced by distortion products and off-frequency listening. Accordingly, the bandwidths might differ with the experimental method.

Adult↗
PubMed1995

Relationship between psychophysical tuning curves and critical bandwidths.

In Experiment I, band noises were used as signals and pure tones were used as maskers. The conventional psychophysical tuning curves (PTCs) present the following characteristics depending on the signal level; slopes of the PTC are steeper than those of the auditory nerve fibers frequency threshold curve (FTC). This result from the large effect of the combination tones and, especially, of the off-frequency listening. Bandwidths of PTC do not depend on both signal levels and duration, but they are narrower than the equivalent rectangular bandwidth (ERB) of auditory filters. Masked thresholds at tips of PTC are affected by the temporal integration of signal sound at signal levels of 10- and 20-dB SL, but are not affected at 30-dB SL. This implies a close relation between PTCs and critical bandwidths (CB-widths). In Experiment II, pure tones were used as signals and band noise were used as maskers. The low- and high-frequency slopes were steeper in Experiment I. The flat parts of the masked threshold at the tips of curves become broader as the signal duration increased. No such flattening was found at a 30-dB signal level, irrespective of signal duration. The results of Experiment II coincide with the prediction derived from the excitation-pattern model. Masked thresholds at the tip of PTC were the same as in Experiment I. The conventional PTC represents the psychological frequency selectivity, and its 3-dB bandwidth corresponds to the CB-width. However, the quantitative properties depend greatly upon the bandwidths of the band noises used as signals or maskers.

Attention↗
PubMed2000

Loudness discomfort levels in patients with conductive and mixed hearing loss.

OBJECTIVE: The purpose of this study is to investigate the effects of conductive component on the loudness discomfort level (LDL) judgments. The relation between LDL value and the magnitude of air-bone gap in such subjects was also assessed. METHODS: LDLs were obtained from 100 ears of 50 hearing-impaired subjects. Twenty five subjects (50 ears) had either conductive or mixed hearing loss for both ears. Another 25 subjects (50 ears) with bilateral sensorineural hearing loss served as control. LDL measurements were performed using the method reported by Hawkins et al. in 1987. LDL data were plotted and analyzed as a function of hearing loss for three stimulus frequencies (0.5, 1.0 and 2 kHz). Also, LDL values were plotted as a function of air-bone gap in the conductive group. RESULTS: LDLs were significantly higher in subjects with conductive or mixed hearing loss for all three tested frequencies. There is a significant positive correlation between LDL value and the magnitude of air-bone gap for all three test frequencies. Considerable intersubject variability was found in LDLs obtained from subjects with conductive component which prevented the accurate prediction of LDLs from threshold data for such patients. CONCLUSION: The large intersubject variation in LDL data strongly suggests the need for individualized LDL measurements in patients with conductive or mixed hearing loss. Higher LDLs indicates that higher maximal power output can be prescribed for such patients without worrying about loudness intolerance.

Adult↗
PubMed1996

Comparison of various automatic means for measuring mean fundamental frequency.

The purpose of this paper was to evaluate the reliability of, and agreement among, six speech analysis systems in the determination of fundamental frequency. Five male and five female speakers provided oral reading and sustained vowel samples for analysis. Each sample was analyzed five times by each system. The results indicated high reliability for all of the systems for both sexes and both utterance types. Agreement among the systems was high for the male sustained vowels and the female oral reading samples. In contrast, poor agreement occurred among the systems for the male oral reading samples and the female sustained vowels. The findings indicate that the output of these automatic methods tends to be consistent over repeated trials within the systems in their extraction of fundamental frequency; however, agreement among these systems varies.

Adolescent↗
PubMed1997

Effects of perceived listeners on speakers' vocal intensity.

The purpose of this study was to determine the amount of change in speakers' vocal intensity when a listener is located at various perceived versus actual physical distances from a speaker. Twelve men and 12 women with normal voices were asked to read a passage at three interspeaker distances in one of two conditions. In the perceived listener condition, participants were asked to "imagine" that the listener was located 3, 15, or 30 ft away. In the actual listener condition, one of the experimenters stood at each one of the three experimental distances. Conditions were counterbalanced. The results showed that men and women increased vocal intensity levels for all three interspeaker distances regardless of the type of condition. However, women showed larger increases than men at all interspeaker distances in both conditions. Data for both men and women combined showed that the amount of increase is < 6 dB, which indicates that speakers do not follow the inverse square law when raising vocal intensity. Clinical implications of the results are discussed.

Adult↗
PubMed2003

Serotonergic dysfunction in schizophrenia assessed by the loudness dependence measure of primary auditory cortex evoked activity.

Increased serotonergic activity is discussed as an important pathogenetic factor in schizophrenia. Further support for this hypothesis is difficult to obtain due to the lack of valid indicators of the brain's serotonin system. A great deal of evidence discovered through human and animal studies suggests that a weak loudness dependence of auditory evoked potentials (LDAEP) indicates high serotonergic activity and vice versa. The LDAEP is a measure of auditory cortex activity, reflecting increase or decrease of auditory evoked potential amplitudes with increasing tone loudness, which is probably modulated by the serotonergic innervation there. This is true only for the LDAEP of the primary auditory cortex, since this region is more highly innervated by serotonergic fibers than the secondary auditory cortex. The LDAEP (N1/P2 component) of 25 inpatients with schizophrenia free of medication and 25 healthy controls matched by age and gender, were recorded. Using dipole source analysis, the LDAEP of primary (tangential dipole) and this of secondary auditory cortex (radial dipole) was separately analyzed. Following a 4-week treatment with the 5-HT(2) antagonists clozapine or olanzapine, patients were once again studied. The LDAEP of the primary, but not of the secondary auditory cortex, was significantly weaker in the patients with schizophrenia than in healthy volunteers, indicating enhanced serotonergic neurotransmission. After treatment with the 5-HT(2) antagonists, the LDAEP (of the right hemisphere) tended to be increased, indicating normalization of serotonergic function in the patients with schizophrenia. These results suggest that the loudness dependence of primary auditory cortex evoked activity is well suitable to assess serotonergic dysfunction in schizophrenia.

Adult↗
PubMed2003

The startle reflex in schizophrenia: habituation and personality correlates.

Schizophrenia has long been associated with abnormal patterns of arousal that are thought to reflect disturbances in the reticular-activating system of the brain. Psychophysiological investigations of sensory responsivity have repeatedly demonstrated reduced reactivity and habituation to moderately intense stimuli in patients with schizophrenia. While not traditionally used as a measure of physiological arousal, the startle reflex represents an alternative method for studying reactivity and habituation in schizophrenia. This study examined eye blink responsivity to a repeatedly presented intense acoustic startle probe in men with chronic schizophrenia and healthy normal controls. Subjects' personality profiles were also measured, as increased reactivity and arousal have been traditionally implicated as a physiological component to the personality trait of neuroticism. Results indicated that schizophrenic subjects did demonstrate significantly reduced rates of habituation to the acoustic startle probe and higher scores on measures of neuroticism in comparison to normal controls. However, no correlation between habituation rate and neuroticism emerged. These studies replicate previous findings of habituation in schizophrenia and provide further evidence for sensory reactivity disturbances in schizophrenia. The relationship of these findings to cognitive disturbances in schizophrenia is considered and directions for future research are discussed.

Acoustic Stimulation↗
PubMed2003

An ERP study of continuous speech processing. I. Segmentation, semantics, and syntax in native speakers.

Speech segmentation, breaking continuous streams of sound into units that can be recognized, is a necessary step in auditory language processing. To date, most studies of speech segmentation have been limited to behavioral measures that may not index online segmentation as it occurs when listening to natural speech. In the present study, we measured event-related potentials (ERPs) evoked by word-initial and word-medial syllables equated for loudness, length, and phonemic content. This comparison provided an online measure of natural speech segmentation. Word-initial sounds elicited a larger early sensory component (N100). In addition, we measured the effects of semantic and syntactic information on speech segmentation by comparing ERPs to word-initial and word-medial syllables in sentences with varying amounts of semantic and syntactic content. The results indicated that neither semantic nor syntactic information is necessary for the word-onset segmentation effect to be observed. We also identified additional ERP components that index more general semantic and syntactic aspects of natural speech processing.

Adult↗
PubMed1984

Measurement and management of tinnitus. Part I. Measurement.

This paper comprises mainly a description of the clinical practice and experience of the Tinnitus Clinic at the General Hospital, Nottingham, which has evolved as a result of and during the course of a 3-year DHSS-sponsored study of the efficacy of tinnitus maskers. The paper is supported by some experimental data from laboratory, epidemiological and clinical studies, and by information on the number of patients who can be seen, the staff required and the methods used in the clinic.

Humans↗
PubMed1984

Type A and type B behaviour patterns, task type and sensitivity to noise.

The present study examined sensitivity to noise in subjects with Type A and Type B behaviour patterns as a function of the type of task being performed. Twenty Type A and 20 Type B subjects, selected by means of Bortner's scale (French version), were exposed to steadily increasing noise levels (68-110 dBA) while performing two tasks. The first was simple (crossing out) and the second was more complex (memorizing nonsense syllables). There was no difference between the groups on the simple task, but on the more complex task Type A and Type B subjects reacted differently, the former maintaining their level of tolerance while the latter lowered theirs. High investment and the desire to succeed may lead Type A subjects to ignore the acoustic environment and/or to deny the aversive aspects of noise as cognitive strategies for coping with stress.

Adult↗
PubMed1985

Sensitivity to noise in a community sample: II. Measurement of psychophysiological indices.

A sample of 77 women of high and low noise sensitivity in 1977, living in areas of high and low exposure to aircraft noise, were interviewed in the community in 1980. High, intermediate and low noise sensitive women were compared, using measures of blood pressure, heart rate, skin conductance, hearing threshold, uncomfortable loudness level and magnitude estimation of six tones. These physiological measures did not clearly distinguish different noise sensitivity groups, except that highly noise sensitive women had a consistently slower heart rate. Noise sensitivity was not related to auditory threshold. In the high aircraft noise area there were significantly more skin conductance responses than in the low aircraft noise area irrespective of noise sensitivity. This may be the result of chronic exposure to high aircraft noise.

Adolescent↗
PubMed2002

Intracerebral sources of human auditory steady-state responses.

The objective of this study was to localize the intracerebral generators for auditory steady-state responses. The stimulus was a continuous 1000-Hz tone presented to the right or left ear at 70 dBSPL. The tone was sinusoidally amplitude-modulated to a depth of 100% at 12, 39, or 88 Hz. Responses recorded from 47 electrodes on the head were transformed into the frequency domain. Brain electrical source analysis treated the real and imaginary components of the response in the frequency domain as independent samples. The latency of the source activity was estimated from the phase of the source waveform. The main source model contained a midline brainstem generator with two components (one vertical and lateral) and cortical sources in the left and right supratemporal plane, each containing tangential and radial components. At 88 Hz, the largest activity occurred in the brainstem and subsequent cortical activity was minor. At 39 Hz, the initial brainstem component remained and significant activity also occurred in the cortical sources, with the tangential activity being larger than the radial. The 12-Hz responses were small, but suggested combined activation of both brainstem and cortical sources. Estimated latencies decreased for all source waveforms as modulation frequency increased and were shorter for the brainstem compared to cortical sources. These results suggest that the whole auditory nervous system is activated by modulated tones, with the cortex being more sensitive to slower modulation frequencies.

Acoustic Stimulation↗
PubMed2004

The selectivity of neurons in the auditory zone of the mouse midbrain to the direction of movement of a spectral notch in wide-band noise.

A series of noise signals was synthesized with spectral notches whose central frequencies moved regularly along the frequency range (from low frequencies to high and from high frequencies to low), imitating movement of the sound source in the vertical plane. The spike responses of neurons in the inferior colliculus of the mouse (Mus musculus) to noise signals changed as the spectral notch moved relative to the excitatory and inhibitory areas of the receptive fields of the neurons and depended on the notch width. Disinhibition reactions in the inhibitory zones were more marked when a frequency notch in the inhibitory zone was followed by a frequency notch in the excitatory part of the response. It is suggested that the selectivity of neurons to the direction of movement of the spectral notch in a noise signal is based on the interaction of the excitatory and inhibitory inputs. The overall set of neuron responses can provide information on the movement of the sound source in acoustic space.

Acoustic Stimulation↗
PubMed2004

Activity of neurons in the mouse inferior colliculus in relation to the position and direction of displacement of spectral contrast.

The variability of the responses of neurons in the inferior colliculus of the mouse (Mus musculus) to sequences of signals of noise bands and wide-band noise with spectral notches with regular changes (by 1/12 octave) in the central band frequency or notch frequency was studied. When the width of spectral changes was 1/3 octave, neurons with strong inhibitory influences in the excitatory zone of the response ("inhibition-dependent" neurons) showed low levels of spike activity if the noise band completely covered the excitatory part of the response. The most effective stimuli for these neurons were spectral contrasts passing through the center of the excitatory part of the response (through or close to the characteristic frequency). The responses of neurons to spectral contrasts created by noise bands and noises with notches were identical. It is suggested that approximation of the inhibitory and excitatory inputs sharpens the frequency tuning of neurons to the position of the spectral contrasts, as occurs in the visual system. The selectivity of neurons to the direction of moving spectral contrasts is manifest as a difference in responses when they move from the excitatory area of the response to the inhibitory and vice versa. The functional significance of the contrast mechanism for the analysis of sound source movement based on direction-dependent spectral features associated with the transfer characteristics of the external ear is discussed.

Acoustic Stimulation↗
PubMed1992

Hypnosis, reporting bias, and suggested negative hallucinations.

We examined the role of reporting bias in hypnotic negative hallucinations by using a paradigm in which reporting bias was assessed independently of perceptual change. In Experiment 1, highly hypnotizable subjects reported significant loudness reductions when tested for hypnotic deafness. Later, however, these subjects biased their reported loudness reductions in the absence of perceptual change, and their reporting bias scores were almost as large as their hypnotic deafness reports. Subjects also biased their ratings of strategy use. In Experiment 2, ratings of blindness given in response to a hypnotic negative visual hallucination suggestion were significantly correlated with reporting bias scores obtained in this paradigm. Although hypnotic blindness and hypnotic deafness correlated significantly, the partial correlation between these variables was nonsignificant when reporting bias scores were statistically controlled. Theoretical implications are discussed.

Adult↗