Tone Multi Frequency Research Articles

Multifrequency Analysis of Masseter Vestibular Evoked Myogenic Potentials in Young Adults.

The purpose of this study was to explore the dynamics of multifrequency tone bursts on the masseter vestibular evoked myogenic potential (mVEMP) parameters. Furthermore, it sought to determine the optimal frequency tuning of mVEMP responses. Twenty young adults with normal hearing sensitivity participated in the study. Bilateral tone burst evoked mVEMPs were obtained using the zygomatic montage at 250-, 500-, 750-, 1000-, 1500-, and 2000-Hz stimulation frequencies. Self-monitoring biofeedback was given during the procedure to confirm the tension of the masseter muscle between 49.9 and 150.6 rms. Furthermore, the electromyography (EMG) scaling was done to avoid any muscle-related irregularities. Tone burst evoked mVEMPs were found to be 100% present at the stimulation frequencies of 250, 500, 750, and 1000 Hz. There were no ear and gender effects seen for any of the frequencies. Significant shortening of the P1 and N1 latencies with increasing stimulation frequencies was observed. The peak-to-peak amplitude was the highest at 500 Hz and lowest at 2000 Hz tone bursts under both EMG scaled and unscaled conditions. The present revealed higher response rates and larger amplitudes study of mVEMP at lower frequencies, and, therefore, the frequency tuning was seen for the stimulation frequency at 500 Hz.

Comparison of Multifrequency Narrow-Band CE-Chirp and Tone Burst Evoked Cervical Vestibular Evoked Myogenic Potentials.

Cervical vestibular evoked myogenic potentials (cVEMPs) are inhibitory myogenic responses that have commonly been elicited using a variety of stimuli. Yet the comparison of the effects of multifrequency tone bursts and narrow-band Claus Elberling chirps (NB CE-chirps) on cVEMPs has never been studied in homogeneous age groups. The present study focused on comparing the effect of multifrequency NB CE-chirps and tone bursts on the various parameters of cVEMP responses in normal-hearing younger adults. A within-group study design was applied, and purposive sampling was utilized for the collection of the data sample. The present study involved the elicitation of NB CE-chirp and tone burst-evoked cVEMPs across four-octave frequencies in 25 normal-hearing younger adults. NB CE-chirp and tone burst evoked cVEMPs were found to have a 100% response rate for all frequencies except 4,000 Hz. Across frequencies, P1 and N1 latencies were seen to be significantly shorter for NB CE-chirps than tone bursts at 500 Hz and 1,000 Hz stimulation. No differences were seen in the P1N1 amplitudes and interaural asymmetry ratio between the two stimuli across all four-octave frequencies. Furthermore, we found a significantly higher number of ears tuned to NB CE-chirps than tone bursts at 500 Hz. Comparative differences in the latencies of cVEMP responses between and within stimuli could be due to the variation in stimuli duration. Also, the difference in amplitudes across stimulation frequencies might have resulted due to the predominance of saccular responses at lower mechanical resonance frequencies. Thus, the tuning was also seen at 500 Hz and was relatively higher for NB CE-chirps than tone bursts.

Robust dual-tone multi-frequency tone detection using k-nearest neighbour classifier for a noisy environment

Purpose Due to the continuous and rapid evolution of telecommunication equipment, the demand for more efficient and noise-robust detection of dual-tone multi-frequency (DTMF) signals is most significant. Design/methodology/approach A novel machine learning-based approach to detect DTMF tones affected by noise, frequency and time variations by employing the k-nearest neighbour (KNN) algorithm is proposed. The features required for training the proposed KNN classifier are extracted using Goertzel's algorithm that estimates the absolute discrete Fourier transform (DFT) coefficient values for the fundamental DTMF frequencies with or without considering their second harmonic frequencies. The proposed KNN classifier model is configured in four different manners which differ in being trained with or without augmented data, as well as, with or without the inclusion of second harmonic frequency DFT coefficient values as features. Findings It is found that the model which is trained using the augmented data set and additionally includes the absolute DFT values of the second harmonic frequency values for the eight fundamental DTMF frequencies as the features, achieved the best performance with a macro classification F1 score of 0.980835, a five-fold stratified cross-validation accuracy of 98.47% and test data set detection accuracy of 98.1053%. Originality/value The generated DTMF signal has been classified and detected using the proposed KNN classifier which utilizes the DFT coefficient along with second harmonic frequencies for better classification. Additionally, the proposed KNN classifier has been compared with existing models to ascertain its superiority and proclaim its state-of-the-art performance.

Enhancement of Ultrasonic De-Icing via Tone Burst Excitation

Previous ultrasonic de-icing research on rotorcraft has demonstrated that applying multifrequency burst actuation schemes has increased the ice protection area coverage of the system. The physical mechanisms responsible for this increase in de-icing performance are modeled using finite elements and tested using both freezer ice and impact ice in the Adverse Environment Rotor Test Stand facility at the Pennsylvania State University. Freezer ice was tested using a 0.035-in.-thick (0.889-mm-thick) titanium grade 2 plate. Impact ice testing was conducted using a 0.035-in.-thick (0.889-mm-thick) stainless steel NACA 0015 airfoil structure (16 in. or 40.64 cm chord). It is proven that the increase in ice shedding area when using multifrequency tone bursts is due to the transient nature of the excitation and not the multimode control of the structure at varying frequencies surrounding the resonance of the structure. During bench-top testing using freezer ice, ultrasonic burst actuation techniques that exploit transient vibrations showed to increase the de-icing performance (as quantified by the ice shedding area) by a factor of 4 when compared to continuous actuation methods. The benefits of tone burst actuation were as large as 10 times that of continuous frequency actuation when testing rotor impact ice affected by centrifugal loads.

Spontaneous firing rate changes in cat primary auditory cortex following long-term exposure to non-traumatic noise: Tinnitus without hearing loss?

Changes of neural activity in animal models have been correlated with tinnitus in humans. For instance, increased spontaneous firing rates (SFR), increased spontaneous neural synchrony, and cortical tonotopic map reorganization may underlie this phantom auditory percept. The aim of this study is to quantify the changes in SFR activity in the cat primary auditory cortex, after long-term exposure to different types of non-traumatic acoustic environments. For that purpose, four different groups of adult cats were exposed to moderate-level (~70dB SPL), behaviorally irrelevant sounds for several weeks to months, and their SFRs were compared with those in control cats. The sounds consisted of random multi-frequency tone pip ensembles with various bandwidths (2–4kHz, 4–20kHz, and a pair of third-octave bands centered at 4 and 16kHz), as well as a “factory noise”. Auditory brainstem response (ABR) thresholds, ABR wave 3 amplitudes at ~55 and 75dB SPL, and distortion product otoacoustic emission (DPOAE) amplitudes were unaffected by the exposure. However, we found that the SFR decreased within the exposure frequency range and increased outside the exposure range. This increased SFR for units with characteristic frequencies outside the exposure frequency range, which was slow to reverse after the exposure offset, suggests a mechanism for tinnitus in the absence of hearing loss.

Spectral-shape preference of primary auditory cortex neurons in awake cats

The study of the influence of spectral envelopes of complex tones on cortical neuron discharges is important with respect to understanding the formant processing of vowels. That the sharpness of formants can contribute to the vowel quality has previously been shown in psychophysical experiments. However, it is unknown how this parameter is reflected by cortical neuron discharges, especially when a formant falls into different portions of the neuronal frequency receptive field (FRF). To show this is the aim of this study focusing on the sustained discharging neurons in the low frequency portion of cat primary auditory cortex (A1). The stimuli were multi-frequency tones whose spectral envelope was sinusoidally modulated with a peak fixed at a neuron's best frequency. The modulation depth, defined as damping-amplitude (DA), varied systematically. Stimulus bandwidth also varied systematically. Large DA at off-center frequencies produces a prominent spectral peak with steep slope, whereas small DA has a less well-defined spectral peak with gentle slope. Single frequency and two tone stimuli served to delineate the excitatory and inhibitory subfields of FRF. The A1 neuron preferred large DA when the sound energy fell into FRF with the relatively large inhibitory-subfield, while the same cell preferred small DA when it fell into FRF with the relatively small inhibitory-subfield. It is concluded that the A1 neuron can estimate steepness of slope of a spectral peak, and that a preference for steep slopes stems from a shift of balance toward the spectral inhibition, whereas a preference for gentle slopes, toward the spectral excitation.

Global well-posedness and multi-tone solutions of a class of nonlinear nonlocal cochlear models in hearing**This work was partially supported by ARO grant DAAD 19-00-1-0524, NSF ITR-0219004 and a fellowship from the John Simon Guggenheim Memorial Foundation.

We study a class of nonlinear nonlocal cochlear models of the transmission line type, describing the motion of basilar membrane (BM) in the cochlea. They are damped dispersive partial differential equations (PDEs) driven by time dependent boundary forcing due to the input sounds. The global well-posedness in time follows from energy estimates. Uniform bounds of solutions hold in the case of bounded nonlinear damping. When the input sounds are multi-frequency tones, and the nonlinearity in the PDEs is cubic, we construct smooth quasi-periodic solutions (multi-tone solutions) in the weakly nonlinear regime, where new frequencies are generated due to nonlinear interaction. When the input consists of two tones at frequencies f1, f2 (f1 < f2), and high enough intensities, numerical results illustrate the formation of combination tones at 2f1 − f2 and 2f2 − f1, in agreement with hearing experiments. We visualize the frequency content of solutions through the FFT power spectral density of displacement at selected spatial locations on the BM.

Musical door chime preferably also combined with a clock for annunciating the time

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Electronic tone generator

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Design and Performance of a Digital Multifrequency Receiver

An experimental multifrequency receiver for recognition of digitally encoded multifrequency signaling was designed, constructed and tested. The receiver is based on a quadrature detection technique that consists of digital demodulation followed by second-order, lowpass digital filtering. The post filtering processing produces an estimate of the amplitude of each of the six multifrequency tones and provides suitable information for thresholding and timing measurements. The receiver performs correctly even when subjected to severe environmental conditions including an analog signal range of 23 dB, 10 ms signal interruptions ('hits') and 20 ms signal spacings. The receiver's operation demonstrates the robustness of the digital signal processing techniques employed. The design of the receiver exploits the use of subsampling techniques to increase the efficiency of the hardware through greater multiplexing. When using subsampling, 128 multifrequency receivers with 16-bit words are realized with 6.5 dual-in-line packages per receiver; commercial TTL logic circuits, a 4-bit serial-parallel pipeline multiplier circuit, serial data and a 16.384 MHz clock are assumed.

Multifrequency tone detection by zero-interval analysis

An algorithm is presented which enables a microprocessor to analyse the zero intervals of the multifrequency signals from a pushbutton telephone. A model has shown that, with a 100 kHz clock, the component frequencies of any signal can be predicted to within ±1% from a 30 ms sample, but the speech immunity requires improvement.

Simple multifrequency-tone detector

An outline is given of a simple method of detecting digitally encoded multifrequency tones.