scholarly journals Perception of frequency modulation is mediated by cochlear place coding

2018 ◽  
Author(s):  
Kelly L. Whiteford ◽  
Heather A. Kreft ◽  
Andrew J. Oxenham
Keyword(s):  
Frequency Modulation ◽  
Auditory Nerve ◽  
Additional Data ◽  
Spike Timing ◽  
Impaired Hearing ◽  
Time Code ◽  
Detection Thresholds ◽  
High Modulation ◽  
Highly Correlated ◽  
Fast Rates

AbstractNatural sounds convey information via frequency and amplitude modulations (FM and AM). Humans are acutely sensitive to the slow rates of FM that are crucial for speech and music. This sensitivity has been thought to rely on precise stimulus-driven auditory-nerve spike timing (time code), whereas a coarser code, based on variations in the cochlear place of stimulation (place code), represents faster FM. Here we test this longstanding theory in listeners with normal and impaired hearing, resulting in widely varying place-coding fidelity. Contrary to predictions, FM detection thresholds at slow and fast rates are highly correlated and closely related to the fidelity of cochlear place coding. We support this conclusion with additional data showing that place-based coding degrades at high modulation rates and in high spectral regions in ways that were previously interpreted as reflecting the limits of fine neural timing. The results suggest a unitary place-based neural code for FM.

scholarly journals The role of cochlear place coding in the perception of frequency modulation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Kelly L Whiteford ◽  
Heather A Kreft ◽  
Andrew J Oxenham
Keyword(s):  
Frequency Modulation ◽  
Auditory Nerve ◽  
Spike Timing ◽  
Impaired Hearing ◽  
Time Code ◽  
Wide Range ◽  
High Carrier ◽  
Time Coding ◽  
Fast Rates

Natural sounds convey information via frequency and amplitude modulations (FM and AM). Humans are acutely sensitive to the slow rates of FM that are crucial for speech and music. This sensitivity has long been thought to rely on precise stimulus-driven auditory-nerve spike timing (time code), whereas a coarser code, based on variations in the cochlear place of stimulation (place code), represents faster FM rates. We tested this theory in listeners with normal and impaired hearing, spanning a wide range of place-coding fidelity. Contrary to predictions, sensitivity to both slow and fast FM correlated with place-coding fidelity. We also used incoherent AM on two carriers to simulate place coding of FM and observed poorer sensitivity at high carrier frequencies and fast rates, two properties of FM detection previously ascribed to the limits of time coding. The results suggest a unitary place-based neural code for FM across all rates and carrier frequencies.

Quantitative FM Spectroscopy at High Temperatures: The Detection of 1CH2 behind Shock Waves

2000 ◽  
Vol 214 (12) ◽  
Author(s):  
G. Friedrichs ◽  
H.Gg. Wagner
Keyword(s):  
High Temperature ◽  
Shock Waves ◽  
High Temperatures ◽  
Frequency Modulation ◽  
Modulation Frequency ◽  
Optical Power ◽  
Time Resolved ◽  
Signal Conversion ◽  
High Modulation ◽  
Singlet Methylene

The technique of time resolved frequency modulation (FM) spectroscopy has been shown to provide a very sensitive means to detect small radicals behind shock waves. Features of high temperature FM spectroscopy behind shock waves will be discussed and a general signal conversion procedure to carry out quantitative concentration measurements will be presented.Using a high modulation frequency, a high modulation index and high total optical power, singlet methylene radicals (α

First-Spike Timing of Auditory-Nerve Fibers and Comparison With Auditory Cortex

1997 ◽  
Vol 78 (5) ◽  
pp. 2438-2454 ◽  
Author(s):  
Peter Heil ◽  
Dexter R. F. Irvine
Keyword(s):  
Auditory Cortex ◽  
Auditory Nerve ◽  
Rise Time ◽  
Peak Pressure ◽  
Inverse Function ◽  
Nerve Fibers ◽  
Spike Timing ◽  
Maximum Acceleration ◽  
Minimum Latency ◽  
Auditory Nerve Fibers

Heil, Peter and Dexter R. F. Irvine. First-spike timing of auditory-nerve fibers and comparison with auditory cortex. J. Neurophysiol. 78: 2438–2454, 1997. The timing of the first spike of cat auditory-nerve (AN) fibers in response to onsets of characteristic frequency (CF) tone bursts was studied and compared with that of neurons in primary auditory cortex (AI), reported previously. Tones were shaped with cosine-squared rise functions, and rise time and sound pressure level were parametrically varied. Although measurement of first-spike latency of AN fibers was somewhat compromised by effects of spontaneous activity, latency was an invariant and inverse function of the maximum acceleration of peak pressure (i.e., a feature of the 2nd derivative of the stimulus envelope), as previously found in AI, rather than of tone level or rise time. Latency-acceleration functions of all AN fibers were of very similar shape, similar to that observed in AI. As in AI, latency-acceleration functions of different fibers were displaced along the latency axis, reflecting differences in minimum latency, and along the acceleration axis, reflecting differences in sensitivity to acceleration [neuronal transient sensitivity (S)]. S estimates increased with spontaneous rate (SR), but values of high-SR fibers exceeded those in AI. This suggests that S estimates are biased by SR per se, and that unbiased true S values would be less tightly correlated with response properties covarying with SR, such as firing threshold. S estimates varied with CF in a fashion similar to the cat's audiogram and, for low- and medium-SR fibers, matched those for AI neurons. Minimum latency decreased with increasing SR and CF. As in AI, the standard deviation of first-spike timing (SD) in AN was also an inverse function of maximum acceleration of peak pressure. The characteristics of the increase of SD with latency in a given AN fiber/AI neuron and across AN fibers/AI neurons revealed that the precision of first-spike timing to some stimuli can actually be higher in AI than in AN. The data suggest that the basic characteristics of the latency-acceleration functions of transient onset responses seen in cortex are generated at inner hair cell–AN fiber synapses. Implications for signal processing in the auditory system and for first-spike generation and adaptation in AN are discussed.

scholarly journals Privacy-preserved data hiding using compressive sensing and fuzzy C-means clustering

2020 ◽  
Vol 16 (2) ◽  
pp. 155014772090874
Author(s):  
Ming Li ◽  
Lanlan Wang ◽  
Haiju Fan
Keyword(s):  
Compressive Sensing ◽  
Data Hiding ◽  
Clustering Algorithm ◽  
Additional Data ◽  
Original Image ◽  
Privacy And Security ◽  
Fuzzy C Means ◽  
Security Issues ◽  
Fuzzy C Means Clustering ◽  
Highly Correlated

Nowadays, digital images are confronted with notable privacy and security issues, and many research works have been accomplished to countermeasure these risks. In this article, a novel scheme for data hiding in encrypted domain is proposed using fuzzy C-means clustering and compressive sensing technologies to protect privacy of the host image. The original image is preprocessed first to generate multiple highly correlated classes with fuzzy C-means clustering algorithm. Then, all classes are further divided into two parts according to proper threshold. One is encrypted by stream cipher, and the other is encrypted and compressed simultaneously with compressive sensing technology for easy data embedding by information hider. The receiver can extract additional data and recover the original image with data-hiding key and encryption key. Experiments and analysis demonstrate that the proposed scheme can achieve higher embedding rate about additional data and better visual quality of recovered image than other state-of-the-art schemes.

scholarly journals A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

2020 ◽  
Vol 10 (8) ◽  
pp. 2693
Author(s):  
Thanh Tung Vu ◽  
Hong Hai Hoang ◽  
Toan Thang Vu ◽  
Ngoc Tam Bui
Keyword(s):  
Frequency Modulation ◽  
High Speed ◽  
Modulation Frequency ◽  
Laser Source ◽  
Interference Signal ◽  
Modulation Amplitude ◽  
Hyperfine Component ◽  
Synchronous Detection ◽  
High Modulation ◽  
Uncertainty Of Measurements

Laser interferometers can achieve a nanometer-order uncertainty of measurements when their frequencies are locked to the reference frequencies of the atom or molecule transitions. There are three types of displacement-measuring interferometers: homodyne, heterodyne, and frequency modulation (FM) interferometers. Among these types of interferometer, the FM interferometer has many advantageous features. The interference signal is a series of time-dependent harmonics of modulation frequency, so the phase shift can be detected accurately using the synchronous detection method. Moreover, the FM interferometer is the most suitable for combination with a frequency-locked laser because both require frequency modulation. In previous research, low modulation frequencies at some tens of kHz have been used to lock the frequency of laser diodes (LDs). The low modulation frequency for the laser source means that the maximum measurement speed of the FM interferometers is limited. This paper proposes a novel contribution regarding the application of a high-frequency modulation for an LD to improve both the frequency stability of the laser source and the measurement speed of the FM interferometer. The frequency of the LD was locked to an I2 hyperfine component at 1 MHz modulation frequency. A high bandwidth lock-in amplifier was utilized to detect the saturated absorption signals of the I2 hyperfine structure and induce the signal to lock the frequency of the LD. The locked LD was then used for an FM displacement measuring interferometer. Moreover, a suitable modulation amplitude that affected the signal-to-noise ratio of both the I2 absorption signal and the harmonic intensity of the interference signal was determined. In order to verify the measurement resolution of the proposed interferometer, the displacement induced by a piezo electric actuator was concurrently measured by the interferometer and a capacitive sensor. The difference of the displacement results was less than 20 nm. To evaluate the measurement speed, the interferometer was used to measure the axial error of a high-speed spindle at 500 rpm. The main conclusion of this study is that a stable displacement interferometer with high accuracy and a high measurement speed can be achieved using an LD frequency locked to an I2 hyperfine transition at a high modulation frequency.

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