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PubMed1989

[The influence of musical experiences on discrimination of two-pure-tone simultaneous intervals].

The purpose of this study was to examine whether experiences of musical instruments influence on discrimination of two-pure-tone simultaneous intervals. Fifteen experienced and 14 inexperienced subjects were asked to compare a standard stimulus with a comparison stimulus whose lower tone was varied from -4 Hz to +4 Hz, and to judge whether they were same or different. One single tone and four two-pure-tone simultaneous intervals, major second, major third, perfect fifth, and major seventh were used as stimuli. The results showed that the experienced subjects were generally more accurate and quicker in the task than the inexperienced subjects. It was suggested that a schema for discrimination of two-pure-tone simultaneous intervals was formed by exercises on musical instruments, and that the inexperienced subjects also had the schema to some extent.

Acoustic Stimulation↗
PubMed2005

Neural correlates of olfactory change detection.

Detecting changes in a stream of sensory information is vital to animals and humans. While there have been several studies of automatic change detection in various sensory modalities, olfactory change detection is largely unstudied. We investigated brain regions responsive to both passive and active detection of olfactory change using fMRI. Nine right-handed healthy, normosmic subjects (five men) were scanned in two conditions while breathing in synchrony with a metronome. In one condition, subjects mentally counted infrequent odors (Attend condition), whereas in the other condition, subjects' attention was directed elsewhere as they counted auditory tones (Ignore condition). Odors were delivered via a nasal cannula using a computer-controlled air-dilution olfactometer. Infrequently occurring olfactory stimuli evoked significant (P < .05, corrected) activity in the subgenual cingulate and in central posterior orbitofrontal cortex, but only in the Ignore condition, as confirmed by direct comparison of the Ignore session with the Attend session (P < .05, corrected). Subgenual cingulate and posterior orbital cortex may therefore play a role in detecting discrepant olfactory events while attention is otherwise engaged in another sensory modality.

Adult↗
PubMed2003

An account of monaural phase sensitivity.

Listeners can detect phase differences between the envelopes of sounds occupying remote frequency regions, and between the fine structures of partials that interact within a single auditory filter. They are insensitive to phase differences between partials that differ sufficiently in frequency to preclude within-channel interactions. A new model is proposed that can account for all three of these findings, and which, unlike currently popular approaches, does not discard across-channel timing information. Sensitivity is predicted quantitatively by analyzing the output of a cochlear model using a spectro-temporal decomposition inspired by responses of neurons in the auditory cortex, and by computing a distance metric between the responses to two stimuli to be discriminated. Discriminations successfully modeled include phase differences between pairs of bandpass filtered harmonic complexes, and between pairs of sinusoidally amplitude modulated tones, discrimination between amplitude and frequency modulation, and discrimination of transient signals differing only in their phase spectra ("Huffman sequences").

Attention↗
PubMed1978

Thresholds for linear amplitude change of a continuous pure tone.

The human auditory sensitivity in detecting linear amplitude change of a continuous pure tone has been studied in normal-hearing subjects. It is shown that for short glide durations (less than 100 ms) the duration of the following plateau exerts a significant influence on the DLI. The average DLI at 1 kHz and 60 dB HL was found to be of the order of 0.8 dB when the intensity glide had a duration of 10 ms and was followed by a much longer plateau. For longer glide durations (greater than or equal to 200 ms) the DLI increased significantly as compared with shorter durations. There was no significant difference between increasing and decreasing intensity change. Significantly larger DLIs were found at 250 and 500 Hz than at 1, 2 and 4 kHz. The sound level was found to have a significant influence on the DLI. At low levels of 40 dB HL, and lower, the increase in DLI for detecting sound levels is highly significant. A falling exponential function offers a mathematical description of the relationship with good fit. It is concluded that an integrating mechanism with an integration time of approx. 200 ms could explain the auditory ability to detect linear amplitude glides of a continuous tone. The results are discussed in relation to previous intensity discrimination data, where pulse pairs, continuous intensity modulation or intensity glides were used as stimuli.

Adult↗
PubMed2003

Learning in discrimination of frequency or modulation rate: generalization to fundamental frequency discrimination.

Fifteen initially inexperienced subjects were trained for 4 weeks (12 2-h sessions) in frequency discrimination with pure tones around 88, 250, or 1605 Hz, or amplitude modulation rate discrimination of noise bands, using modulation rates around 88 or 250 Hz. Before, in the middle of, and after this training period, pure-tone frequency discrimination thresholds (DLFs), harmonic complex tone fundamental frequency discrimination thresholds (DLF0s), and amplitude modulation rate discrimination thresholds (DLFMs) were measured in several conditions including the trained one. Training in pure-tone frequency discrimination resulted in significantly larger improvements in DLF0s when the test complexes contained resolved harmonics than when they were composed of unresolved harmonics. This result supports the hypothesis that the discrimination of the F0 of resolved harmonics shares common underlying mechanisms with the frequency discrimination of pure tones. Training in rate discrimination did not result in larger DLF0 improvements for unresolved than for resolved harmonics.

Acoustic Stimulation↗
PubMed2002

Effects of age and frequency disparity on gap discrimination.

Temporal discrimination was measured using a gap discrimination paradigm for three groups of listeners with normal hearing: (1) ages 18-30, (2) ages 40-52, and (3) ages 62-74 years. Normal hearing was defined as pure-tone thresholds < or = 25 dB HL from 250 to 6000 Hz and < or = 30 dB HL at 8000 Hz. Silent gaps were placed between 1/4-octave bands of noise centered at one of six frequencies. The noise band markers were paired so that the center frequency of the leading marker was fixed at 2000 Hz, and the center frequency of the trailing marker varied randomly across experimental runs. Gap duration discrimination was significantly poorer for older listeners than for young and middle-aged listeners, and the performance of the young and middle-aged listeners did not differ significantly. Age group differences were more apparent for the more frequency-disparate stimuli (2000-Hz leading marker followed by a 500-Hz trailing marker) than for the fixed-frequency stimuli (2000-Hz lead and 2000-Hz trail). The gap duration difference limens of the older listeners increased more rapidly with frequency disparity than those of the other listeners. Because age effects were more apparent for the more frequency-disparate conditions, and gap discrimination was not affected by differences in hearing sensitivity among listeners, it is suggested that gap discrimination depends upon temporal mechanisms that deteriorate with age and stimulus complexity but are unaffected by hearing loss.

Adolescent↗
PubMed1992

Formant frequency discrimination by Japanese macaques (Macaca fuscata).

These studies investigated formant frequency discrimination by Japanese macaques (Macaca fuscata) using an AX discrimination procedure and techniques of operant conditioning. Nonhuman subjects were significantly more sensitive to increments in the center frequency of either the first (F1) or second (F2) formant of single-formant complexes than to corresponding pure-tone frequency shifts. Furthermore, difference limens (DLs) for multiformant signals were not significantly different than those for single-formant stimuli. These results suggest that Japanese monkeys process formant and pure-tone frequency increments differentially and that the same mechanisms mediate formant frequency discrimination in single-formant and vowel-like complexes. The importance of two of the cues available to mediate formant frequency discrimination, changes in the phase and the amplitude spectra of the signals, was investigated by independently manipulating these two parameters. Results of the studies indicated that phase cues were not a significant feature of formant frequency discrimination by Japanese macaques. Rather, subjects attended to relative level changes in harmonics within a narrow frequency range near F1 and F2 to detect formant frequency increments. These findings are compared to human formant discrimination data and suggest that both species rely on detecting alterations in spectral shape to discriminate formant frequency shifts. Implications of the results for animal models of speech perception are discussed.

Adult↗
PubMed1992

Temporal modulation transfer functions in patients with cochlear implants.

Thresholds for the detection of amplitude modulation were measured in cochlear implant patients as a function of modulation frequency. Three types of threshold measures were taken: detection of amplitude modulation, detection of low-frequency sinusoidal current waveforms, and detection of beats in two-tone complexes. The temporal modulation transfer function (TMTF), defined as the plot of modulation detection thresholds as a function of modulation frequency, show low-pass filter characteristics with similar cutoff frequencies for all three tasks. The similarity of these three measures suggests a common temporal mechanism. While modulation detection differs somewhat in normal-hearing and implanted listeners, both exhibit the same general characteristics. The TMTFs are low pass with a cutoff frequency near 70 Hz for normal-hearing listeners and near 140 Hz for implanted listeners. Patients with cochlear implants can best detect temporal modulation at modulation frequencies below 300 Hz, and are most sensitive to 80- to 100-Hz modulation. At high carrier levels many implant patients could detect smaller modulation amplitudes than normal-hearing listeners, a finding that is consistent with the smaller intensity DLs for some implanted listeners at high levels. These results demonstrate that, while implant listeners cannot discriminate steady-state, high-frequency stimuli, speech information might be conveyed by the envelope of the high-frequency components of speech.

Auditory Threshold↗
PubMedDate not supplied

Effects of subtle mid-frequency auditory dysfunction upon speech discrimination in noise.

Earlier studies have indicated mid-frequency auditory dysfunction and depressed ability to discriminate speech in noise among noise-exposed listeners with high-frequency hearing loss. The present study was designed to determine whether mid-frequency dysfunction contributed to the depressed speech discrimination performance. Normal listeners, and noise-exposed and older listeners with high-frequency hearing loss listened to word lists presented in competing 'cocktail party' noise under unfiltered and low-pass filter conditions. In the low-pass filter condition the performance of the noise-exposed listeners was superior to that normal listeners, indicating that mid-frequency auditory dysfunction on the part of noise-exposed listeners does not contribute to their difficulties discriminating unfiltered speech in noise. The performance of the older listeners was below that of the two other groups in both filtered and unfiltered conditions, indicating greater difficulty discriminating speech than would be predicted only on the basis of high-frequency hearing loss.

Adult↗
PubMed2002

The effects of methylphenidate on prepulse inhibition during attended and ignored prestimuli among boys with attention-deficit hyperactivity disorder.

RATIONALE AND OBJECTIVES: The present study investigated attentional modification of prepulse inhibition of startle among boys with and without attention-deficit hyperactivity disorder (ADHD). Two hypotheses were tested: (1) whether ADHD is associated with diminished prepulse inhibition during attended prestimuli, but not ignored prestimuli, and (2) whether methylphenidate selectively increases prepulse inhibition to attended prestimuli among boys with ADHD. METHODS: Participants were 17 boys with ADHD and 14 controls. Participants completed a tone discrimination task in each of two sessions separated by 1 week. ADHD boys were administered methylphenidate (0.3 mg/kg) in one session and placebo in the other session in a randomized, double-blind fashion. During each series of 72 tones (75 dB; half 1200-Hz, half 400-Hz), participants were paid to attend to one pitch and ignore the other. Bilateral eyeblink electromyogram startle responses were recorded in response to acoustic probes (50-ms, 102-dB white noise) presented following the onset of two-thirds of tones, and during one-third of intertrial intervals. RESULTS: Relative to controls, boys with ADHD exhibited diminished prepulse inhibition 120 ms after onset of attended but not ignored prestimuli following placebo administration. Methylphenidate selectively increased prepulse inhibition to attended prestimuli at 120 ms among boys with ADHD to a level comparable to that of controls, who did not receive methylphenidate. CONCLUSIONS: These data are consistent with the hypothesis that ADHD involves diminished selective attention and suggest that methylphenidate ameliorates the symptoms of ADHD, at least in part, by altering an early attentional mechanism.

Arousal↗
PubMed2001

Relative pitch perception in Japanese monkeys (Macaca fuscata).

To investigate whether monkeys perceive relative pitch, the author trained 3 Japanese monkeys (Macaca fuscata) to detect changes from rising to falling contours of 3-tone sequences. Tone sequences were presented serially with transposition, so monkeys were urged to attend to cues other than the absolute frequency of a component tone. Results from probe tests with novel sequences showed that monkeys discriminated by the relative pitch when the frequency ranges of sequences were within the training range, showing a similar tendency as birds in previous studies (e.g., S. H. Hulse, J. Cynx, & J. Humpal, 1984).

Animals↗
PubMed1988

Duration discrimination of steady and gliding tones: a new method for estimating sensitivity to rate of change.

Thresholds for the detection of differences in duration were measured in a two-alternative, forced-choice task for four types of signals, all centered at 2000 Hz: (1) sinusoids fixed in frequency and level; (2) sinusoids of fixed frequency whose level was swept up or down by 5 or 10 dB; (3) sinusoids of fixed level whose frequency was swept up or down by 100 Hz; and (4) sinusoids whose level was swept up or down by 10 dB and whose frequency was swept up or down by 100 Hz. For types (2)-(4), the direction of the sweeps was fixed within a run. The duration of the standard was either fixed at 750 ms or was varied randomly from trial to trial by up to +/- 7% about 750 ms. The duration of the comparison signal was initially 100 ms greater than that of the standard and was varied adaptively to determine threshold. The pattern of results was similar for all four subjects tested. Duration-discrimination thresholds for the signals that were swept in level and/or frequency were lower than those for the fixed signal, typically by 15-20 ms. This indicates that subjects were sensitive to the rate of change of frequency and/or level and could use this as a cue for duration discrimination. The Weber fraction for rate of change was estimated to be about 0.05-0.06 and was similar for changes in level and in frequency.

Adult↗
PubMed1987

An automatic test for frequency discrimination.

Békésy audiometry has been applied to the determination of the frequency discrimination threshold. The automatic test for frequency discrimination is performed by means of a modified automatic audiometer at fixed frequencies, each administered for a duration of 60 s. The test involves the stimulus of a series of pairs of tone bursts of 500 ms duration: the frequency of one of the tone bursts (f0) is constant, while the other (f0 + delta f) gradually increases and decreases according to the subject's response. The tracings obtained facilitate the evaluation of the discrimination capability of the subject. The pattern obtained from a sample of normally hearing people was analysed in order to evaluate the precision of this procedure.

Adolescent↗
PubMed1989

Comparison of single-channel extracochlear and multichannel intracochlear electrodes in the same patient.

A postlingually deaf patient who had been using a single-channel extracochlear implant for 5 years was reimplanted in the same ear with a 22-channel intracochlear device after electrical failure of the internal receiver. In the subsequent follow-up period, auditory performance was investigated in a series of tests with nonspeech and speech material. Two weeks after processor fitting most test scores were equal or better with the new implant. Three months later, with only minimal training, the patient's performance in sentence, numerals and vowel tests was markedly improved. Analysis of vowel confusion matrices indicated a high percentage of F2 information perceived (53% compared with 5% with the single-channel device) and somewhat less F1 information (35% compared with 4% using the single-channel device). Further improvements of speech discrimination (especially consonant recognition) are conceivable if the fine temporal resolution provided by some single-channel devices can be combined with the spectral resolution of multichannel systems.

Cochlear Implants↗
PubMed1990

Discrimination of slight changes in tone frequency applied in audiological diagnosis of noise-induced hearing impairment.

Investigations were carried out to examine the ability to differentiate low-grade changes in tone frequency in 58 subjects (116 ears) with noise-induced hearing impairment. The results were compared with those obtained in an age-matched group of healthy controls with normal hearing acuity. Statistically, the slight discrimination of frequency changes was found to be significantly worse in the group with noise-induced hearing impairment.

Adult↗
PubMed2004

Effect of age on silent gap discrimination in synthetic speech stimuli.

The difficulty that older listeners experience understanding conversational speech may be related to their limited ability to use information present in the silent intervals (i.e., temporal gaps) between dynamic speech sounds. When temporal gaps are present between nonspeech stimuli that are spectrally invariant (e.g., noise bands or sinusoids), older listeners are less able to resolve temporal gaps than are younger listeners. It has also been demonstrated that temporal gap perception deteriorates as the frequency difference between the sounds bordering the silent gap increases, and this effect becomes more pronounced with age (J. Lister, J. Besing, and J. Koehnke, 2002; J. Lister, J. Koehnke, and J. Besing, 2000). In this study, the effect of age on the ability to discriminate temporal gaps in dynamic stimuli (i.e., changing in frequency and duration over time) was measured in a gap duration discrimination (GDD) task. The participants were two groups of listeners with normal hearing sensitivity through at least 4000 Hz: (a) ages 21-38 years and (b) ages 50-72 years. Stimuli simulated the frequency characteristics of 1 consonant (/s/), a steady-state vowel (/a/), a weak diphthong (/eI/), and a voiced bilabial plosive (/burst/) in 6 combinations: (a) /s-a/, (b) /s-eI/, (c) /a-a/, (d) /eI-eI/, (e) /burst-a/, and (f) /burst-eI/. For each of the 6 phoneme combinations, 2 conditions of stimulus duration were used: (a) fixed, meaning that the durations of leading and trailing noises were fixed at values typical for the speech sounds being simulated, and (b) random, meaning that duration varied randomly within a range acceptable for accurate perception of the speech contrasts. Gap duration difference limens (GDDLs) were significantly larger for the older listeners than for younger listeners. For both groups, GDDLs were poorer for the spectrally dynamic marker pairs (e.g., /burst-eI/) than for the marker pairs that were relatively stable in frequency over time (/a-a/). GDD performance also was poorer for the random conditionthan for the fixed condition. Listener age and hearing sensitivity were significantly correlated, and age was not significantly correlated with GDD when controlling for hearing sensitivity. The authors conclude that temporal resolution (as measured by gap discrimination) is affected by age, stimulus complexity, and, perhaps, by hearing sensitivity in a speech context.

Acoustic Stimulation↗
PubMed1998

Listeners can discriminate among major chord positions.

Listeners judged whether two sequentially presented major chords were the same. When both chords were based on the same root, listeners discriminated between different chord positions, e.g., root position, first inversion, second inversion. The ability of listeners to discriminate between chord positions suggests that harmonic equivalence of different chord positions does not depend on perceptual equivalence and instead arises from a more cognitive representation.

Acoustic Stimulation↗