Amplitude Of Tone Research Articles

Effect of sound intensity on tonotopic fMRI maps in the unanesthetized monkey

The monkey's auditory cortex includes a core region on the supratemporal plane (STP) made up of the tonotopically organized areas A1, R, and RT, together with a surrounding belt and a lateral parabelt region. The functional studies that yielded the tonotopic maps and corroborated the anatomical division into core, belt, and parabelt typically used low-amplitude pure tones that were often restricted to threshold-level intensities. Here we used functional magnetic resonance imaging in awake rhesus monkeys to determine whether, and if so how, the tonotopic maps and the pattern of activation in core, belt, and parabelt are affected by systematic changes in sound intensity. Blood oxygenation level-dependent (BOLD) responses to groups of low- and high-frequency pure tones 3–4 octaves apart were measured at multiple sound intensity levels. The results revealed tonotopic maps in the auditory core that reversed at the putative areal boundaries between A1 and R and between R and RT. Although these reversals of the tonotopic representations were present at all intensity levels, the lateral spread of activation depended on sound amplitude, with increasing recruitment of the adjacent belt areas as the intensities increased. Tonotopic organization along the STP was also evident in frequency-specific deactivation (i.e. “negative BOLD”), an effect that was intensity-specific as well. Regions of positive and negative BOLD were spatially interleaved, possibly reflecting lateral inhibition of high-frequency areas during activation of adjacent low-frequency areas, and vice versa. These results, which demonstrate the strong influence of tonal amplitude on activation levels, identify sound intensity as an important adjunct parameter for mapping the functional architecture of auditory cortex.

Role of initial conditions on noise from underexpanded pipe jets

An experimental investigation of acoustic radiation from underexpanded air jets of different shear layer thicknesses has been performed. The initial shear layer thickness variation is achieved by allowing the jet to exit through pipes of various lengths. The lengths of the pipes considered for the present study are in the range 1≤L/D≤6. The pressure ratio of the pipe jets is varied from 3 to 7 corresponding to fully expanded jet Mach numbers of 1.35≤Mj≤1.92. Acoustic radiation is characterized in terms of overall sound pressure level, directivity, tonal, and broadband shock associated noise. Increase in initial shear layer thickness in pipe jets results in the decrease of screech tone amplitude (by up to 20 dB), and increase in broadband shock associated noise level. Turbulent mixing noise levels are higher for shorter (L/D) pipe jets compared to longer ones. Longer pipe jets exhibit more number of screech modes while the shorter pipe jets show only one or two screech modes. The screech frequency and the peak frequency of broadband shock associated noise do not show much variation with increase in initial shear layer thickness. The screech frequency of a jet with negligible shear layer thickness (orifice jet) is found to be higher compared to those of finite shear layer thickness from pipe jets.

Difference limen for dynamic center‐of‐gravity signals.

We hypothesize that central auditory processing of the dynamic center‐of‐gravity (COG) of a pair of tones is similar to that for a single tone that undergoes sinusoidal frequency modulation (FM). The signal COG can be moved dynamically by introducing amplitude modulation to two fixed‐frequency anchor tones separated by one, or more, equivalent rectangular bandwidths (ERB). The phase relationship between the sinusoidal amplitude modulators of the anchor tones is used to control the magnitude of the COG deviation. In this study, the amplitude of the anchor tones and the depth of AM were identical between intervals. The phase relationship of the modulators was manipulated to control the deviation in the COG. To test our hypothesis, we compared FMDLs with COGDLs at three center frequencies and three modulation rates. First, difference limens were measured for the FM signals in partial replication of [Ozimek and Sek (1990)]. Next, COGDLs were measured. Initial attempts to match COG deviation to FM deviation were unsuccessful because the task was too difficult. Consequently, the modulation depth of the COGDL signals was fixed at 0.5, which resulted in replicable performance across subjects. Data for both the FMDL and COGDL task will be discussed. [Work supported by NIH and ASEE.]

The impacts of age and absolute threshold on binaural lateralization.

Listeners varying in audiometric thresholds (70‐dB range) and in age (52‐year range) lateralized complex tones relative to a diotic standard. Stimuli were composed of one, two, three, or six tones amplitude modulated at a rate of 75 Hz. Carrier frequencies were selected from a set of seven values (roughly log‐spaced between 700 and 7000 Hz) and sensation levels were equated across listeners. Baseline performance was obtained for one‐ and two‐component signals and the effects of diotic interference were assessed with two‐, three‐, and six‐component signals. For all signals, the dichotic components contained interaural differences in time (whole‐waveform delay), level, or both across a range of values. Listeners with higher audiometric thresholds performed more poorly in all conditions, despite the use of equivalent sensation levels. Diotic interferers reduced performance, but there were no additional impacts of age or absolute threshold. Statistical analyses indicated that the impacts of age were primarily due to the co‐occurring increases in pure‐tone thresholds, suggesting that: (1) absolute threshold is a better predictor of binaural ability than age and (2) reduced sensitivity to binaural differences is not addressed by presenting stimuli at equivalent sensation levels. [Work supported by VA RRD CDA‐2 C4963W.]

Harmonic and Intermodulation Performance of Metallic Carbon Nanotube (MCNT) and Complementary Carbon Nantube Field Effect Transistor (CNTFET) Amplifier

This paper presents a simple mathematical model for the output-voltage (current)/ input-voltage characteristic of the carbon nanotube field effect transistor (CNTFET) complementary inverting amplifier and the metallic carbon nanotube (MCNT) interconnect. The model, basically a Fourier series, yields closed-form expressions for the amplitudes of the harmonic and intermodulation components of the output voltage (current) resulting from a multisinusoidal input voltage. The special case of a two-tone equal-amplitude input voltage is considered in detail. The results show that the harmonic and intermodulation performance of the complementary CNTFET-based inverting amplifier and the MCNT interconnect is strongly dependent on the values of the amplitudes of the input tones with the third-order intermodulation component dominating over a wide range of the input voltage amplitudes. The results also show that while the harmonics may exhibit minima, the intermodulation products are almost monotonically increasing with the increase in the input voltage amplitude and exhibit no minima.

What Do Primates Hear? A Meta-analysis of All Known Nonhuman Primate Behavioral Audiograms

Research on the hearing abilities of nonhuman primates dates back >70 yr and there are audiograms —graphs showing hearing sensitivity over a range of frequencies— for 29 different species including representatives from almost every major group. However, the methods used to obtain the audiograms have been nearly as varied as the number of species tested. I sought to determine the degree to which one can directly compare the audiograms by examining several factors that could have a significant impact on the results: the behavioral conditioning procedure employed to train and test the subjects, the type of transducer used to deliver the test tones, the procedure used to calibrate the amplitude of the test tones, the acoustic enclosure used to minimize ambient noise, and the method used to determine the final threshold values. Audiograms produced using speakers cannot be compared directly with those produced using headphones, and in some cases the calibration procedure and testing chamber may also limit the potential for interspecific comparisons. Based on the findings, I provide 2 lists of optimal primate audiograms: 1 for speaker-derived audiograms and the other for headphone-derived audiograms. I measured a set of audiometric variables on each of the optimal audiograms, and phylogenetic comparisons of the data show that superfamilies of primates display unique patterns of hearing sensitivity, particularly at frequencies in the lower range. Lastly, I discuss the implications for behavioralists investigating primate vocalizations in the field.

Why Should Markedness Constraints be Relative? -- Four Case Studies in Tone Sandhi Directionality

UC Berkeley Phonology Lab Annual Report (2009) Why should Markedness Constraints be Relative? - Four Case Studies in Tone Sandhi Directionality 1 Te-hsin Liu liu.tehsin@berkeley.edu Abstract This paper presents a novel analysis on tone sandhi directionality, introducing a family of relative markedness constraints, i.e. M IN M OD (minimize modulation) and M IN A MP (minimize amplitude of contour tones), to account for the apparently ungoverned traffic of sandhi operations. A closer look at the data leads to the conclusion that tone sandhi directionality is not output-driven but directionality-driven. This observation echoes Hyman & VanBik’s analysis on Hakha-Lai, according to which output-based generalizations fail to capture the input-output relations (2002). Keywords: conflicting directionality, tone sandhi, Optimality theory. 1. Introduction The increasing interest in conflicting directionality has heightened the need for phonological theories to account for such complex and apparently unpredictable phenomena. The material targeted can range from segmental elements (i.e. palatalization in Japanese mimetic words), stress placement (i.e. stress patterns in Selkup) to directional tone sandhi (i.e. Hakha Lai, some Chinese dialects). The present study focuses on the third pattern of conflicting directionality, tone sandhi directionality. In some Chinese dialects, sandhi rules must apply from left to right to derive the outputs for some trisyllabic sequences and from right to left to account for the others. One common point among them is that morphosyntactic structures play no role, a left-branching string and a right-branching string generating the same surface form. The research presented in this paper, supported by Fyssen Foundation, is partly based on a talk given jointly with Joaquim Brandao de Carvalho at the Seventeenth Manchester Phonology Meeting held on May 28-30, 2009. I am grateful to Larry Hyman as well as the audience of the conference, especially Stuart Davis, Andrew Nevins, Marc van Oostendorp and Danial Hall, for their precious comments and feedback. All errors are of course my own responsibility.

Pulse Arterial Tone and Airway Obstruction in Sleep Apnea

Objective Determine if continuous pulse arterial tone (PAT) amplitude correlates with upper airway obstructions observed during simultaneous real-time magnetic resonance imaging (RT-MRI) in subjects with Obstructive Sleep Apnea (OSA). Methods A prospective series of 20 subjects diagnosed with mild to severe OSA by polysomnography, Fujita classification, Functional Outcomes of Sleep Questionnaire (FOSQ) and Epworth Sleepiness Score (ESS) underwent continuous RT-MRI during a 90-minute nap without sedation. The upper airway at the mid-saggittal plane was visualized in real time (33 fps) using a sliding window algorithm (RTHawk system). Continuous pulse arterial tone amplitude was simultaneously monitored (Watch-PAT, Itamar Inc, Israel). Results Changes in PAT amplitude were in phase with upper airway narrowing and obstruction from tongue, soft palate, and epiglottis movements. Airway obstructive events occurred coincident to 60% or greater decreases in PAT amplitude. The image sequence associated with each PAT amplitude decrease demonstrated the precise location of the obstruction. Pre-surgical site of airway obstruction and post-surgical cause of persistent obstruction was clearly identified. Conclusions RT-MRI with simultaneous and continuous PAT signal recording during natural sleep is an innovative and improved method for more precisely characterizing airway obstructions in patients with mild to severe OSA. This approach may be valuable for planning surgical treatments, potentially improving the success of these procedures.

Auditory steady-state response and auditory brainstem response thresholds in children

The inclusion of the auditory steady-state response (ASSR) into test-batteries for objective audiometry has allowed for clinical comparisons with the most widely used procedure, the auditory brainstem response (ABR). The current study describes ASSR and ABR thresholds for a group of infants and young children with various types and degrees of hearing loss. A sample of 48 subjects (23 female) with a mean age of 2.8+/-1.9 years SD were assessed with a comprehensive test-battery and classified according to type and degree of hearing loss. Thresholds were determined with a broadband click-evoked ABR and single frequency ASSR evoked with continuous tones (0.25-4 kHz) amplitude modulated (67-95 Hz). Mean difference scores (+/-SD) between the ABR and high frequency ASSR thresholds were 9.8 (+/-11), 3.6 (+/-12) and 10.5 (+/-12) dB at 1, 2 and 4 kHz, respectively. An ASSR mean threshold for 2-4 and 1-4 kHz compared to the ABR threshold revealed an average difference of 7 (+/-9) and 7.9 (+/-8) dB, respectively. The overall correlation between the ABR and ASSR thresholds was highest for the mean ASSR thresholds of 2-4 and 1-4 kHz (r=0.92 for both conditions). Correlations between the ABR and individual ASSR frequencies were slightly less (0.82-0.86). The average of the 2-4 kHz ASSR thresholds correlated best with the click-evoked ABR for all categories of hearing loss except for the sensorineural hearing loss category for which the 1-4 kHz ASSR average was better correlated to ABR thresholds. Findings demonstrate the reliability of verifying high frequency ASSR thresholds with a click-evoked ABR as an important cross-check in infants for whom behavioural audiometry may not be possible.

The acoustical bright spot and the erroneous localization of tones by human listeners

In free‐field sound localization experiments, human listeners estimated the locations of sine tones originating at 13 loudspeakers that spanned a range of azimuths from 0 degrees (straight ahead) to 90 degrees (extreme right). During the experiments the tone amplitudes and phases were measured in the listener's ear canals. Because of the acoustical bright spot, measured interaural level differences (ILD) were found to be a nonmonotonic function of azimuth at frequencies above about 1000 Hz. In source identification experiments at 1500 Hz, there was no correlation between estimated location and the interaural phase difference. There was high correlation with ILD, causing listeners to make large localization errors for azimuths greater than about 55 degrees. In a second experiment, listeners judged the direction of movement of sounds from one source to another. Errors in the second experiment could be well predicted from the localization responses in the source identification experiment. The ear canal measurements showed that, in principle, listeners could localize successfully by using the levels in the two ears independently. However, localization performance remained poor even after extensive training. Work supported by the NIDCD, grant DC00181.

A Psychophysiological Study of Auditory Illusions of Approach and Withdrawal in the Context of the Perceptual Environment

Auditory perception of the depth of space is based mainly on spectral and amplitude changes of sound waves originating from the sound source and reaching the listener. The perceptive illusion of movement of an auditory image caused by changes in amplitude and/or frequency of the signal tone emanating from an immobile loudspeaker was studied. Analysis of data obtained from the participants revealed the diapason of combinations of amplitude and frequency changes for which the movement direction was perceived similarly by all participants, despite significantly different movement assessment criteria. Additional auditory and visual information of the conditions of radial movement (near or far fields) determined listeners' interpretation of changes in the signal parameters. The data obtained about the perception of approach and withdrawal models are evidence of the fact that the principal cues of the perception of the distance of immobile sound sources manifests similarly to that of an auditory image moving along a radial axis.

First spike latency and spike count as functions of tone amplitude and frequency in the inferior colliculus of mice

Spike counts (SC) or, spike rate and first spike latency (FSL), are both used to evaluate the responses of neurons to amplitudes and frequencies of acoustic stimuli. However, it is unclear which one is more suitable as a parameter for evaluating the responses of neurons to acoustic amplitudes and frequencies, since systematic comparisons between SC and FSL tuned to different amplitudes and frequencies, are scarce. This study systematically compared the precision and stability (i.e., the resolution and the coefficient variation, CV) of SC- and FSL-function as frequencies and amplitudes in the inferior colliculus of mice. The results showed that: (1) the SC-amplitude functions were of diverse shape (monotonic, nonmonotonic and saturated) whereas the FSL-amplitude functions were in close registration, in which FSL decreased with the increase of amplitude and no paradoxical (an increase in FSL with increasing amplitude) or constant (an independence of FSL on amplitude) neuron was observed; (2) the discriminability (resolution) of differences in amplitude and frequency based on FSL are higher than those based on SC; (3) the CVs of FSL for low amplitude stimuli were smaller than those of SC; (4) the fraction of neurons for which BF = CF (within ±500 Hz) obtained from FSL was higher than that from SC at any amplitude of sound. Therefore, SC and FSL may vary, independent from each other and represent different parameters of an acoustic stimulus, but FSL with its precision and stability appears to be a better parameter than SC in evaluation of the response of a neuron to frequency and amplitude in mouse inferior colliculus.

Analysis of Tones in Cantonese Speech Based on the Command-Response Model

As one of the major Chinese dialects, Cantonese has a tone system consistingof nine lexical tones and three additional changed tones, which is considerablymore complex than that of Mandarin. The most important acoustic feature characterizingthese tones is the contour of the voice fundamental frequency (the F₀ contour).In this article we present an approach to modeling F₀ contours of Cantoneseutterances, based on an extension of the command-response model. Analysis-bysynthesisof F₀ contours of the utterances with a fixed carrier frame, in which a targetsyllable with each tone type is embedded, shows that each tone type can berepresented by a specific pattern (polarity, timing, and amplitude) of tone commands.These patterns are found to be essentially maintained in F₀ contours of theutterances with unconstrained text. With the definition of these tone commandpatterns, the command-response model not only provides a novel phonologicaldescription of tones, but also gives high accuracy of approximations to F₀ contoursof Cantonese utterances and allows one to analyze various tonal phenomenain quantitative terms. Quantitative distinctions between various tones are thenrevealed by statistical analysis of the timing and amplitude of tone commands.Especially, systematic alignment in timing is found between the onsets/offsets oftone commands and the rhyme of a syllable, and hence a set of constraints can beintroduced, which together with those on tone command amplitudes and phrasecommand parameters, is then applied for generating F₀ contours of Cantoneseutterances. The validity of the approach is verified by perceptual evaluation of thesynthetic speech stimuli with model-generated F₀ contours, both on the intelligibilityof tones and on the naturalness of prosody.

Supersonic Cavity Flows and Their Control

A detailed experimental study of supersonic, Mach 2, flow over a three-dimensional cavity was conducted using shadowgraph visualization, unsteady surface pressure measurements, and particle image velocimetry. Large-scale structures in the cavity shear layer and visible disturbances inside the cavity were clearly observed. A large recirculation zone and high-speed reverse flow was revealed in the cavity. In addition, supersonic microjets were used at the leading edge to suppress flow unsteadiness within the cavity. With a minimal mass flux (blowing coefficient B c = 0.0015), the activation of microjets led to reductions of up to 20 dB in the amplitudes of cavity tones and of more than 9 dB in the overall sound pressure levels. The microjet injection also modified the cavity mixing layer and resulted in a significant reduction in the flow unsteadiness inside the cavity as revealed by the shadowgraphs and the velocity-field measurements.

Learning of interaural-level-difference discrimination with a 0.5-kHz tone in human adults

Sound-source location on the horizontal plane is primarily determined by two cues: interaural time differences (ITDs) for low-frequency sounds and interaural level differences (ILDs) for high-frequency sounds. Though not available in natural listening environments, ILDs in low-frequency sounds, when artificially delivered to listeners through headphones, also can be used to lateralize sounds. Little is known about the neural processing of such low-frequency ILDs. Here, the modifiability of this processing was examined by training human adults on ILD discrimination with a 0.5-kHz tone on the midline. After nine 1-h daily training sessions, trained listeners (n=6) improved significantly more than untrained controls (n=8) on the trained condition. This learning generalized to a 4-kHz tone and a 0.5-kHz tone amplitude modulated at 30 Hz, but appeared not to generalize to a 1-kHz tone, an off-midline position, or ITD discrimination with the trained tone. This overall learning pattern differs from those previously obtained for ILD at 4 kHz and ITD at 0.5 kHz using the same training paradigm [Wright and Fitzgerald, Proc. Natl. Acad. Sci. U.S.A. 98, 12307–12312 (2001)], suggesting that the processes involved in low-frequency ILD discrimination differ from those encoding high-frequency ILDs and low-frequency ITDs, at least at the neural site(s) affected by training. [Work supported by NIH/NIDCD.]

Numerical simulation of the generation mechanism of axisymmetric supersonic jet screech tones

In this paper an axisymmetric computational aeroacoustic procedure is developed to investigate the generation mechanism of axisymmetric supersonic jet screech tones. The axisymmetric Navier-Stokes equations and the two equations standard k-ϵ turbulence model modified by Turpin and Troyes [“Validation of a two-equation turbulence model for axisymmetric reacting and non-reaction flows,” AIAA Paper No. 2000-3463 (2000)] are solved in the generalized curvilinear coordinate system. A generalized wall function is applied in the nozzle exit wall region. The dispersion-relation-preserving scheme is applied for space discretization. The 2N storage low-dissipation and low-dispersion Runge-Kutta scheme is employed for time integration. Much attention is paid to far-field boundary conditions and turbulence model. The underexpanded axisymmetric supersonic jet screech tones are simulated over the Mach number from 1.05 to 1.2. Numerical results are presented and compared with the experimental data by other researchers. The simulated wavelengths of A0, A1, A2, and B modes and part of simulated amplitudes agree very well with the measurement data by Ponton and Seiner [“The effects of nozzle exit lip thickness on plume resonance,” J. Sound Vib. 154, 531 (1992)]. In particular, the phenomena of modes jumping have been captured correctly although the numerical procedure has to be improved to predict the amplitudes of supersonic jet screech tones more accurately. Furthermore, the phenomena of shock motions are analyzed. The predicted splitting and combination of shock cells are similar with the experimental observations of Panda [“Shock oscillation in underexpanded screeching jets,” J. Fluid. Mech. 363, 173 (1998)]. Finally, the receptivity process is numerically studied and analyzed. It is shown that the receptivity zone is associated with the initial thin shear layer, and the incoming and reflected sound waves.

Determination of Amplitudes of the Frequency Components present in a Single Tone Amplitude Modulated Carrier through Lissajous Figures

This paper presents a technique for determining the amplitudes of the frequency components present in a single tone amptitude modulated sinusoidal carrier wave through the use of Lissajous figures. The amplitude modulated signal and the reference sine wave are applied to the deflection plates of cathode ray oscilloscope (CRO), which is being operated in X-Y mode. Appropriate selection of the reference signal amplitude based on a certain criterion used in conjunction with the Lissajous figure will enable the determination of the amplitudes of the side frequency components. The mathematical equations, experimental results along with the limitations of this method are presented.

The effect of reflector with sound-absorbing material on supersonic jet noise

This paper describes an experimental work to investigate the effect of a reflector on supersonic jet noise radiated from a convergent-divergent nozzle with a design Mach number 2.0. In the present study, a metal reflector and reflectors made of three different sound-absorbing materials (grass wool and polyurethane foam) were employed, and the reflector size was varied. Acoustic measurement is carried out to obtain the acoustic characteristics such as frequency, amplitude of screech tone and overall sound pressure level (OASPL). A high-quality schlieren optical system is used to visualize the detailed structure of supersonic jet. The results obtained show that the acoustic characteristics of supersonic jet noise are strongly dependent upon the jet pressure ratio and the reflector size. It is also found that the reflector with sound-absorbing material reduces the screech tone amplitude by about 5–13dB and the overall sound pressure levels by about 2–5dB, compared with those of the metal reflector.

Designing multisine excitations for nonlinear model testing

This paper deals with the design of bandpass multisine excitations appropriate for microwave nonlinear model testing. A formal analysis showed that if the output power spectral density of a general nonlinear dynamic system is used as a metric for signal similarity, then it is possible to derive a set of statistical characteristics to be approximated. Using these nth-order extensions of the autocorrelation or the power spectral-density functions as the approximation goals, the multisine design problem is formulated as an optimization scheme where the various tone amplitudes and phases become the target design variables.

Modeling the growth rate of distortion product otoacoustic emissions by active nonlinear oscillators.

In this work, growth-rate curves of the 2 f1-f2 distortion product otoacoustic emission (DPOAE) are analyzed in a population of 30 noise exposed subjects, including both normal-hearing and hearing impaired subjects. A particular embedded limit-cycle oscillator equation is used to model the cochlear resonant response at the cochlear places of the primary and secondary tone frequencies (f2 and 2 f1-f2). The parameters of the oscillator equation can be directly interpreted in terms of effectiveness of the cochlear feedback mechanisms associated with the active filter amplification. A two-sources paradigm is included in the model, in agreement with experimental evidence and with the assumptions of more detailed full cochlear models based on the transmission line formalism. According to this paradigm, DPOAEs are nonlinearly generated at the cochlear place that is resonant at frequency f2, and coherently reflected at the 2 f1-f2 place. The analysis shows that the model, which had been previously used to describe the relaxation dynamics of transient evoked otoacoustic emissions (TEOAEs), also correctly predicts the observed growth rate of the DPOAE response as a function of the primary tones amplitude. A significant difference is observed between normal and impaired ears. The comparison between the growth rate curves at different frequencies provides information about the dependence of cochlear tuning on frequency.