Steady-state Tone Research Articles

Humans attend to signal duration but not temporal structure for sound detection: Steady-state versus pulse-train signals

Most sounds fluctuate in amplitude, but do listeners attend to the temporal structure of those fluctuations when trying to detect the mere presence of those sounds? This question was addressed by leading listeners to expect a faint sound with a fixed temporal structure (pulse train or steady-state tone) and total duration (300 ms) and measuring their ability to detect equally faint sounds of unexpected temporal structure (pulse train when expecting steady state) and/or total duration (<300 ms). Detection was poorer for sounds with unexpected than with expected total durations, replicating previous outcomes, but was uninfluenced by the temporal structure of the expected sound. The results disagree with computational predictions of the multiple-look model, which posits that listeners attend to both the total duration and temporal structure of the signal, but agree with predictions of the matched-window energy-detector model, which posits that listeners attend to the total duration but not the temporal structure of the signal. Moreover, the matched-window energy-detector model could also account for previous results, including some that were originally interpreted as supporting the multiple-look model. Taken together, at least when detecting faint sounds, listeners appear to attend to the total duration of expected sounds but to ignore their detailed temporal structure.

Acoustical coupling between two guitars, onset variation, and timbre perception

Acoustical coupling between simultaneously played musical instruments has been observed at times, for instance, between adjacent organ pipes [F. Trendelenburg et al., Akustische Zeitschrift 7-20 (1938)]. The observation here concerns two guitars that reveal a different timbre when played simultaneously (A) in contrast to when played separately with the tracks being mixed afterwards (B). Alternatively, the two guitars are played separately but each with a simultaneous steady-state tone presented by a speaker while the frequency relates to the key (C). Subjects rated the music produced under the paradigms A and C as being similar and music produced under the paradigms A and B as being dissimilar, likewise for B and C. The differences were attributed to timbre. For analysis, a mechanical plugging mechanism replaces the musician on the first guitar, whereas the second guitar is replaced by a steady-state tone. While most of the partial tones remain unaffected, partial tones above 3 kHz rise more sharpely and reach higher levels during onset when a simultaneous tone is present compared to when it is absent. Although these partial tones decline rapidly and finally progress toward comparable levels with and without the simultaneous tone, the perceived timbre differs noticeably.

Mouthpiece pressing force for pitch and loudness control in playing the French horn

Using a force-sensing French horn mouthpiece developed by the present authors, lip pressing force was examined during pre-attack and post-attack phases of 2-sec sustained tone production at varied pitches (87, 174, 349, 466, and 698 Hz) and dynamics (95, 100, 105, 110, and 115 dB) performed by 12 highly trained horn players. Dependent variables examined were: force at the onset of sound, a peak of the force rate before the sound onset, and mean and SD forces during steady state tone production. All of these force variables increased nearly linearly with pitch. They also increased lightly with louder dynamics. The pitch-related and dynamic-related increase of the force varied largely among the players. These findings indicate that skilled horn performances are supported by pre-attacking the mouthpiece pressure properly to prepare for a target pitch at target dynamics. The notable inter-player difference in force production in skilled players suggests a proper level of mouthpiece pressures witch differs among players due possibly to congenital physical properties of their lips.

Abstract P604: Astrocyte-dependent Regulation of Vascular Tone: Role in Hypertension

Clinical studies support that untreated hypertension (HT) accelerates the development of vascular cognitive impairment (VCI). Yet, the underlying mechanisms for VCI are not known. In a recent study we demonstrated the role of astrocytes in the regulation of parenchymal arteriole (PA) steady-state vascular tone. Here we hypothesized hypertension results in structural and functional changes to the neurovascular unit resulting in enhanced astrocytic TRPV4 channel-dependent Ca 2+ increases contributing to augmented pressure-induced PA constriction . Functional studies were conducted in brain slices from angiotensin II (AngII) treated mice (600 ng/Kg/min, 28 days). PA arterioles within brain slices were perfused and pressurized and myogenic-evoked diameter changes measured using video microscopy. In addition, using the GLAST-CreERT2 ; R26-lsl-GCaMP3 mice we measure myogenic-evoked Ca 2+ changes in perivascular astrocytes. We demonstrate that HT increases pressure-induced PA tone by 11.14% at 30 mmHg and 12.97% at 60 mmHg (10.88 to 22.02 and 15.46 to 28.43% of tone, P&lt;0.05 and P&lt;0.01, respectively). In ANG II-treated mice, PA myogenic-evoked responses significantly increased astrocytic Ca 2+ oscillations frequency (119.4%, 0.0366 to 0.0803 Hz, P&lt;0.0001). A significant increase in astrocytic Ca 2+ oscillation frequency was also observed after 2 min of AngII (500 nM) bath application (44.8%, 0.0366 to 0.053 Hz, P&lt;0.01) in brain slices from AngII treated mice. Furthermore, using the model of spontaneous hypertensive rat (SHR) we observed that HT differentially increases vascular density and the number of vascular pericytes in cortical layers with highest neuronal densities (L III-V). Finally, while aquaporin 4 (AQP4) expression pattern was not different in the gray matter of SHR compared with WKY rats, a significant increase in unpolarized AQP4 expression was observed in the white matter of SHR. Taken together, this evidence indicates that HT induces functional and structural changes to the neurovascular unit favoring the development of regional brain hypoperfusion likely contributing to the development of VCI.

Sex Hormones Modulate Salbutamol-Elicited Long-Term Relaxation in Isolated Bovine Tracheal Strips

Sex hormones are of interest regarding gender differences in the clinical manifestations of airway diseases. No conclusive data are available on the sex hormone modulation of β-adrenoceptor-mediated responses on airways. To this aim, isolated preparations of bovine trachea were used to establish the sex hormone influence on salbutamol-elicited relaxation. This had 2 components, a full acute relaxation followed by a loss of efficacy, close to half of the effect. The remaining half was reverted by the β-blocker, propranolol. The loss of salbutamol-elicited relaxation might reflect the receptor desensitization, as shown by the lack of effect by subsequent administration of salbutamol, and the decrease in the immunostaining of β₂-adrenoceptors. Sex hormones differently modified the salbutamol-elicited response. Testosterone, but not other androgens or estradiol, had a synergic effect, facilitating the acute relaxation and decreasing the loss of spasmolytic effect, associated with an increase in the latency of desensitization and a decrease in the time taken to reach long-term steady-state tone. These effects, not modified by the antiandrogen flutamide or epithelium removal, seem to be independent of a modulation of β₂-adrenoceptor desensitization. Testosterone also relaxed preparations with desensitized β-adrenoceptor. Therefore, testosterone modulates tracheal smooth muscle tone, facilitating bronchodilation caused by β₂-adrenoceptor agonists which might be of pharmacological interest.

Validation of multi-channel auditory steady-state response in adults with sensorineural hearing loss

For various medico-legal and financial reasons, some patients may clinically demonstrate an exaggerated hearing loss that varies in degree, nature and laterality. The purpose of this study was to evaluate whether multi-channel auditory steady-state response measurement can be used as an objective test of auditory thresholds in adults with sensorineural hearing loss. This was a prospective, comparative, experimental research design study conducted in an academic medical centre. From January to June 2007, 142 subjects (284 ears) with varying degrees of sensorineural hearing loss were included. Four commonly used frequencies (500, 1000, 2000 and 4000 Hz) were evaluated. Both pure tone thresholds and multi-channel auditory steady-state response thresholds were obtained for each ear in all subjects. The correlation of auditory steady-state response thresholds and pure tone thresholds was assessed. The time taken for multi-channel auditory steady-state response testing was also recorded. Results for multi-channel auditory steady-state response thresholds and pure tone thresholds were compared for each test frequency. A difference of less than 15 dB was found in 71 per cent of patients, while a difference of less than 20 dB was found in 83 per cent. Correlation between auditory steady-state response thresholds and pure tone thresholds, expressed as the correlation coefficient (r), was 0.89, 0.95, 0.96 and 0.97 at 500, 1000, 2000 and 4000 Hz, respectively. The strength of the relationship between auditory steady-state response thresholds and pure tone thresholds increased with increasing frequency and increasing degree of hearing loss. The recorded auditory steady-state response thresholds were used to calculate regression lines predicting pure tone threshold results. The mean estimated pure tone thresholds calculated from these regression lines were all within 10 dB of the actual recorded pure tone thresholds. The average multi-channel auditory steady-state response test duration was 42 minutes per patient. Measurement of multi-channel auditory steady-state response could be a powerful, convenient electro-physiological examination with which to objectively certify clinical hearing impairment in adults.

The Franssen effect illusion in budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia guttata)

The properties of the Franssen effect (FE) were measured in budgerigars and zebra finches. To elicit the FE, listeners are presented with a signal which has been split into a transient component, carrying an abrupt onset and ramped offset and separated in space from the sustained component which has a slowly rising onset and longer duration. When these two signals are played under certain conditions, the perception is that of a long-duration steady state tone being played at the location of the transient. The birds were trained using operant conditioning methods on a categorization task to peck a left key when presented with a stimulus from a left speaker and to peck a right key when presented with a stimulus from a right speaker. Once training was completed, FE stimuli were presented during a small proportion of trials. The FE was measured at speaker separations of 60 degrees and 180 degrees in both echoic and echoic-reduced conditions. Both species of birds exhibited the FE, although to varying degrees, across conditions. These results show that nonmammals also experience the FE illusion in confusing listening situations in a manner similar to mammals, suggestive of similar auditory processing mechanisms.

Responses of inferior colliculus neurons to SAM tones located in inhibitory response areas

In order to examine the effect of inhibition on processing auditory temporal information, responses of single neurons in the inferior colliculus of the chinchilla to sinusoidally amplitude-modulated (SAM) tones alone and the presence of a steady-state tone were obtained. The carrier frequency of the SAM tone was either the characteristic frequency (CF) or a frequency in the inhibitory response area of a studied neuron. When the carrier frequency was set to the neuron’s CF, neurons responded in synchrony to the SAM-tone envelope, as expected. When the carrier frequency was set to a frequency at which pure tones produced inhibition, SAM tones elicited little or no response, also as expected. However, when the same SAM tone was paired with a pure tone whose frequency was set to the neuron’s CF, responses synchronized to the SAM tone envelope were obtained. These modulated responses were typically one-half cycle out-of-phase with the response to the SAM tone at CF, suggesting that they arose from cyclic inhibition and release from inhibition by the SAM tone. The results demonstrate that the representation of temporal information by inferior colliculus neurons is influenced by temporally-patterned inhibition arising from locations remote from CF.

Tonal portrait of a pipe organ

Measurement techniques are described that enable the steady state tone color (timbre) of a musical instrument to be quantified. The system is applied to sounds from the pipe organ in the Great Hall of Sydney University. A one-third octave normalized loudness spectrum that is independent of pitch is derived for each set of notes from selected ranks of pipes. From the normalized spectrum, sharpness and tristimulus coordinates are computed, the latter being independent of both pitch and loudness. Measurements made on different ranks of pipes or made at different times are compared with the aid of spectrum dissimilarity and tristimulus diagrams.

Responses to propofol in the pulmonary vascular bed of the rat.

Although a great deal is known about responses to propofol, controversy remains about its mechanism of action. The present study was undertaken to investigate the direct effects of 2,6-diisopropyl phenol, disodium edetate, and its intralipid emulsion in the rat pulmonary vascular bed and to better understand the mechanisms involved in propofol-mediated responses. The effects of N omega-l-nitro-l-arginine benzyl ester (L-NABE), an inhibitor of nitric oxide synthase, of the cyclooxygenase blocker, meclofenamate, and the K + ATP channel antagonist, U-37883A, an ATP-sensitive potassium channel antagonist, on responses to propofol, acetylcholine, nitroglycerin, and isoproterenol were investigated in the isolated blood-perfused rat lung under low tone and high steady-state tone. Propofol produced a dose-dependent decrease in pulmonary arterial perfusion pressure. L-NABE significantly reduced vasodilator responses to acetylcholine, whereas the nitric oxide synthase inhibitor had no significant effect on responses to propofol. Meclofenamate significantly reduced vasodilator responses to arachidonic acid without effecting responses to propofol. Responses to propofol were not significantly changed in the presence of U-37883A, whereas U-37883A reduced vasodilator responses to levcromakalim. Additionally, 2,6-diisopropylphenol in a pure preparation as well as an intralipid preparation similar to propofol emulsion had no significant effect while disodium edetate had a dose-dependent depressor effect under high steady-state tone. Propofol has significant vasodilator activity in the pulmonary vascular bed of the rat but responses to propofol are not mediated or modulated by the release of nitric oxide, opening of K + ATP channels, or the release of vasodilator cyclooxygenase products.

The effects of tone exposure on the inner ear functions in the guinea pig: impact tone vs. steady state tone.

The damage-risk criterion (DRC) for hearing supposes that sound exposure with equal energy implies equal risk for noise-induced hearing loss (NIHL). We measured cochlear microphonics (CM), compound action potential (CAP), endocochlear potential (EP) and K+ ion concentration in the scala media, to see if the same level of Leq24h (impact tone and steady state tone) induced the same physiological changes in the inner ear function or not. Regarding the equal energy principle (EEP), we also examined if the EEP is appropriate or not at exposure of moderate level tone. We also checked how the time interval between impact tones affects or not the inner ear functions at the same Leq24h tone exposure. Therefore we used exposure at 1 pulse/second or 1 pulse/3 seconds and steady state tone exposure at Leq24h=90, 85 and 80 dB. The results are the following. Both steady state and impact tone exposure causes change of the electrophysiological data. First, CM maximum output voltage after exposure to impact tone of 115 dB (Leq24h=90 dB) was lower than after exposure to a 8 kHz steady state tone of 90 dB. CAP threshold (below 10 microV) obtained after the 115 and 110 dB exposure of impact tone were 5-10 dB higher than that of steady state tone of 90 dB. The negative EP induced by impact tone exposures showed the same tendency as the CM experiments. Having more frequent pulses (1 pulse/second vs. to 1 pulse/3 seconds) showed more inhibition. The K+ concentration time course remained similar to the control when the Leq24h was low (80 dB). Impact tone exposure induced stronger effects to the inner ear at exposure of moderate level tone than that of steady state tone of Leq24h.

Diameter dependence of myogenic tone of human pial arteries. Possible relation to distensibility.

Responses to changes in intraluminal pressure of isolated human pial arteries (200 to 1200 microns i.d.) obtained from patients undergoing neurosurgery were measured. The vessels were cannulated and pressurized (60 mm Hg); vascular diameter and intraluminal pressure were recorded simultaneously. After spontaneous development of steady state tone, intraluminal pressure was changed to both higher and lower levels in random sequence. Human pial arteries exhibited myogenic responses and maintained their diameter over the pressure range of 20 to 100 mm Hg. The level of myogenic tone observed at 30 mm Hg did not vary significantly with artery diameter. In contrast, at 60 and 90 mm Hg, the extent of myogenic tone increased as the diameter decreased (up to 70% to 80% of maximum in 200-microns i.d. arteries). The arteries contracted to KCl 30 mmol/L, norepinephrine 1 mumol/L, and vasopressin 0.1 mumol/L and relaxed to acetylcholine 3 mumol/L. The extent of these responses did not vary with the diameter of the artery. Arterial distensibility, represented by the slope of the tangent of the passive pressure-diameter curve at lower pressures (5 to 50 mm Hg), increased as arteries became smaller. This is consistent with the possibility that the level of myogenic tone is related to vessel distensibility. Human omental arteries of comparable size did not develop myogenic tone but contracted to KCl and norepinephrine and relaxed to acetylcholine to an extent similar to pial arteries. There is a specific gradient of myogenic responsiveness in human pial arteries that varies inversely with their diameter. This tone does not develop in all vascular beds. These levels of tone in the pial circulation would be expected to be of profound functional significance by allowing blood flow to vary widely.

Further evidence implicating a cytochrome P-450-mediated reaction in the contractile tension of the lamb ductus arteriosus.

The authors have recently provided evidence implicating the cytochrome P-450 system in the generation of contractile tension of the ductus arteriosus. To confirm this possibility, carbon monoxide (CO/O2 ratio, 0.27) and cytochrome P-450 inhibitors [4-phenylimidazole; 14-isocyano,15-(methoxymethyleneoxy)-5Z,8Z,11 Z-eicosatrienoic acid; 9-hydroxyellipticine; alpha-naphthoflavone] were tested on the isolated ductus arteriosus from mature fetal lambs equilibrated at low (4-26 mm Hg) or high (229-694 mm Hg) O2 partial pressure (PO2). Carbon monoxide completely relaxed intact vessel wall preparations and preparations consisting of only the muscle. Carbon monoxide relaxation was reversed by illumination with monochromatic light and the peak for the photoactivated contraction occurred at 450 nm. 4-Phenylimidazole (100 and 1,000 microM) was also a relaxant agent, and its action was manifest at both low and high PO2. Unlike 4-phenylimidazole, the isonitrile compound (5 microM) and 9-hydroxyellipticine (10 and 100 microM) were relaxant only at low PO2 and were also less potent. At the same PO2, alpha-naphthoflavone (10 microM) barely reduced ductal tension. Treatment of the ductus with either a combination of superoxide dismutase (60 or 150 U/ml) and catalase (40 or 1,000 U/ml) or mannitol alone (80 mM) failed to alter the steady-state tone at low PO2 and the contractile response to O2. Arachidonic acid was tested on tissues pretreated with the dual cyclooxygenase and lipoxygenase inhibitor, BW755C (10 microM), and produced a weak relaxation at a concentration of 1 microM or higher. 5,6-Epoxytrienoic acid relaxed the untreated tissue, and its action was abolished by indomethacin (2.8 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Percussive voice generator for an electronic musical instrument

A keyboard operated electronic musical instrument in which a number of tone generators are assigned to actuated keyswitches in which a combination of a transient voice and a steady state tone is generated by implementing a discrete Fourier transform employing a selected sequence of harmonic coefficients. A harmonic sequence select logic in cooperation with signals from actuated tone switches provide the selected sequence of harmonic coefficients. A percussion coefficient is added to the sequence of harmonic coefficients in response to a percussion control signal. Various playing modes are disclosed. In one mode the transient voice is generated with the actuation of the first keyswitch on a selected keyboard, and other subsequent actuations are ignored. In a second mode, a transient voice is actuated if at the time of a keyswitch actuation no other transient voice is being generated.

Steady-state vascular responses to graded hypoxia in isolated lungs of five species.

In the isolated pig lung exposed to graded levels of hypoxia, steady-state pulmonary vasomotor tone is maximum at an O2 tension (PO2) of 50 Torr. Below 50-Torr decreases in PO2 cause steady-state tone to fall below this maximum. To determine whether this stimulus-response relation was peculiar to pigs, we measured the steady-state relation between PO2 and vasomotor tone in the isolated lungs of dogs, rabbits, cats, and ferrets, by using identical techniques in each species. Marked species differences were apparent in both the level of PO2 required to elicit responses and the amplitude of the responses. The ferret and the pig had the largest vasoconstrictor responses to hypoxia. No significant responses were obtained in the dog. The cat and rabbit were intermediate responders. In the ferret, cat, and rabbit, the stimulus-response relationship was biphasic, as in the pig. On the average, maximal constriction occurred at an PO2 of 25 Torr. When PO2 was lowered below 25 Torr, steady-state tone fell. Thus pulmonary vasodilation at low PO2 occurs in the isolated lungs of several species.

Vocal shadowing under conditions of normal and altered laryngeal sensation.

Five adult male subjects vocally matched the pitches of tones in a steady-state tone matching task (SSTMT) and vocally shadowed frequency changes in a frequency modulated tone matching task (FMTMT). Matching was done in both a normal condition and a condition of topical anesthesia of the laryngeal mucosa. Pitch matching accuracy was not seriously altered in the anethesia condition, but anesthetized subjects required more time and had slower velocities in effecting transitions between tones on the FMTMT, as compared to normal. In both conditions there was a direct proportionality between interval size and each of the time and velocity variables examined, while frequency lowering was generally faster than frequency raising. Analysis of subject response strategies on the FMTMT revealed recurring patterns, described here as Overshoot, Undershoot, Oscillate and Hit. Fewer Hit, and more Oscillate, patterns were observed for the anesthesia condition as compared to normal. It was concluded that the FMTMT, as compared to the SSTMT, required finer and more rapid laryngeal control to coordinate respiratory driving pressures and glottal resistance, and hence was more susceptible to impairment of the laryngeal mucosal reflexogenic system. Implications of the data for modeling certain mechanical and physiological aspects of laryngeal control are discussed.

Patterns of residual masking for sounds with speech-like characteristics

Flexible instrumental facilities that permit the administration of psychoacoustic tests and the generation of stimuli under computer control have been developed for the purpose of determining poststimulatory threshold shifts in the context of speech-like sound stimulation. In an initial series of experiments, the system has been used to investigate certain of the auditory effects of brief sinusoidal ramps. The experiments have dealt with 1) matching the pitch of a steady tone to the 'pitch' of a short sweep tone, and 2) with the pattern of residual masking associated with such sweep-tone stimuli. The major result of the pitch-matching experiments is compatible with previous findings in the literature, i.e., subjects tend to place the comparison tone at a frequency close to the terminal value of the ramps. Patterns of residual masking were determined for three conditions of stimulation: 1500-Hz tone, 1000 to 1500 Hz, and 2000 to 1500 Hz sweep-tones (all 50 ms long). The sweep-tone patterns do not exhibit uniform masking over the frequency range of the ramps. They resemble the pattern obtained for the steady-state 1500-Hz tone. Moreover, they display maxima of masking at frequencies that approach the median frequencies of the pitch matches. In neither case does the sweep-tone pattern exhibit greater masking in the frequency region beyond the terminal value of the ramp. The latter result is examined in relation to the recent discussion in the literature of a perceptual overshoot or extrapolation mechanism.

Effect of Wall Material on the Steady-State Tone Quality of Woodwind Instruments

A clarinet blown with an artificial embouchure was connected to one end of a large pipe with absorbing material at the other end so that the sound usually radiated was absorbed instead. Under these conditions, the sound radiated from the vibrating body was measured and found to be 48 dB below the sound normally produced by the instrument at the same location. Acceleration levels measured on the body with a vibration meter were correlated with the sound radiated by the body, both for the artificially blown clarinet and for clarinets set into vibration with an attachment energized by a complex signal. The figures obtained were used to check other woodwind instruments. Results showed that the body sound should be at least 37 dB below the normal sound for all instruments measured. The effect of nonrigid walls was checked by comparing tubes of brass and soft TYGON plastic blown on the embouchure, measuring the harmonic structure of the internal standing wave produced and the frequencies and Q's of the resonance modes. The differences were small. It is concluded that the vibrations of the walls of a woodwind instrument do not affect its steady tone either by radiating sound themselves or by affecting the harmonic structure of the internal standing wave.

Harmonic Structure of the Tone of the Bassoon

The purpose of this investigation was to examine quantitatively and in greater detail than had previously been possible the harmonic structure of the steady-state tone of the bassoon. First, an attempt was made to determine the location of formants and the extent to which harmonic structure varies with sound-pressure level. Second, analyses were made of the tones of a group of professional bassoonists of recognized ability to determine the extent to which the harmonic structure of the tone varies from one player to another. Finally, analyses were made of the tones produced by the author to determine the extent to which harmonic structure varies from one sampling to another in the playing of a single individual. It was found that (1) there is a strong formant extending approximately from 440–500 cps and a weaker one from 1220–1280 cps; (2) the difference between the mean strengths of the fortissimo tones and the pianissimo tones of the professional bassoonists was only 10 dB; and (3) the variance in the strengths of the partials from sampling to sampling in the playing of a single individual tends to be approximately 75% as great as that from one player to another.

Phase Effects in Monaural Perception

Experiments are reported demonstrating that the envelope wave shape of a complex steady-state tone is an important factor in audible perception. In particular, it strikingly influences sensations of roughness or smoothness and is related to a sensation of apparent pitch. As envelope wave shape depends on the phases as well as the amplitudes of the components, effects of this type can be produced by changes in the phase alone of but a single component or group of components. The results provide general verification of a limitation placed by Helmholtz on theoretical grounds as to the degree to which his phase rule might be expected to be true. The experiments were conducted at such levels that subjective tones produced by non-linearity in the ear are not believed to influence the results. It is suggested that these results emphasize the importance of time factors in the phenomena of aural perception.