scholarly journals Discrimination of amplitude-modulation depth by subjects with normal and impaired hearing

2016 ◽  
Vol 140 (5) ◽  
pp. 3487-3495 ◽  
Author(s):  
Josef Schlittenlacher ◽  
Brian C. J. Moore
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Impaired Hearing

scholarly journals Contribution of onset/offset information of modulation to amplitude modulation depth discrimination

2008 ◽  
Vol 123 (5) ◽  
pp. EL111-EL115 ◽  
Author(s):  
Derek R. Edwards ◽  
Jungmee Lee ◽  
Jennifer Andrews ◽  
Aileen Wong
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Depth Discrimination

scholarly journals Suppression of amplitude modulation induced by polarization mode dispersion using a multi-degree-of-freedom fiber filter

2018 ◽  
Vol 6 ◽  
Author(s):  
Rao Li ◽  
Youen Jiang ◽  
Zhi Qiao ◽  
Canhong Huang ◽  
Wei Fan ◽  
...  
Keyword(s):  
High Power ◽  
Amplitude Modulation ◽  
Transmission Spectrum ◽  
High Speed ◽  
Large Scale ◽  
Modulation Depth ◽  
Free Spectral Range ◽  
Polarization Mode Dispersion ◽  
Polarization Mode ◽  
Mode Dispersion

Polarization mode dispersion (PMD) in fibers for high-power lasers can induce significant frequency modulation to amplitude modulation (FM-to-AM) conversion. However, existing techniques are not sufficiently flexible to achieve efficient compensation for such FM-to-AM conversion. By analyzing the nonuniform transmission spectrum caused by PMD, we found that the large-scale envelope of the transmission spectrum has more serious impacts on the amount of AM. In order to suppress the PMD-induced FM-to-AM conversion, we propose a novel tunable spectral filter with multiple degrees of freedom based on a half-wave plate, a nematic liquid crystal, and an axis-rotated polarization-maintaining fiber. Peak wavelength, free spectral range (FSR), and modulation depth of the filter are decoupled and can be controlled independently, which is verified through both simulations and experiments. The filter is utilized to compensate for the PMD-induced FM-to-AM conversion in the front end of a high-power laser facility. The results indicate that, for a pulse with phase-modulation frequency of 22.82 GHz, the FM-to-AM conversion could be reduced from 18% to 3.2% within a short time and maintained below 6.5% for 3 h. The proposed filter is also promising for other applications that require flexible spectral control such as high-speed channel selection in optical communication networks.

scholarly journals Binaural summation of amplitude modulation involves weak interaural suppression

2018 ◽  
Author(s):  
D.H. Baker ◽  
G. Vilidaite ◽  
E. McClarnon ◽  
E. Valkova ◽  
A. Bruno ◽  
...  
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Visual Signal ◽  
Data Sets ◽  
Single Object ◽  
Ecological Constraints ◽  
Binaural Summation ◽  
Eeg Data ◽  
Signal Combination ◽  
The Brain

AbstractThe brain combines sounds from the two ears, but what is the algorithm used to achieve this summation of signals? Here we combine psychophysical amplitude modulation discrimination and steady-state electroencephalography (EEG) data to investigate the architecture of binaural combination for amplitude-modulated tones. Discrimination thresholds followed a ‘dipper’ shaped function of pedestal modulation depth, and were consistently lower for binaural than monaural presentation of modulated tones. The EEG responses were greater for binaural than monaural presentation of modulated tones, and when a masker was presented to one ear, it produced only weak suppression of the response to a signal presented to the other ear. Both data sets were well-fit by a computational model originally derived for visual signal combination, but with suppression between the two channels (ears) being much weaker than in binocular vision. We suggest that the distinct ecological constraints on vision and hearing can explain this difference, if it is assumed that the brain avoids over-representing sensory signals originating from a single object. These findings position our understanding of binaural summation in a broader context of work on sensory signal combination in the brain, and delineate the similarities and differences between vision and hearing.

Design and Simulation of a Polarization-Independent Active Metamaterial Terahertz Modulator

2013 ◽  
Vol 455 ◽  
pp. 167-172 ◽  
Author(s):  
Li Shuang Feng ◽  
Bo Hao Yin ◽  
Zhen Zhou ◽  
Jia Wei Sui ◽  
Chen Long Li
Keyword(s):  
Theoretical Model ◽  
Resonance Frequency ◽  
Amplitude Modulation ◽  
Modulation Depth ◽  
Maximum Amplitude ◽  
High Modulation ◽  
Terahertz Communication ◽  
Modulation Rate ◽  
Polarization Independent ◽  
Modulation Speed

The design and simulation of a polarization-independent active metamaterial terahertz modulator is presented in this work. The device incorporates an array of gold triple SRRs on an n-doped gallium arsenide layer to create an active metamaterial terahertz modulator with a high modulation depth, a high modulation speed and an especial polarization-independent performance for use in terahertz communication, imaging and sense.We established the theoretical model and simulatedthe key performances of the device with Ansoft HFSS.The results showed that the device exhibits a polarization-insensitivebehavior with a maximum amplitude modulation depth of 71% and a modulation rate of3.2Mbps at the resonance frequency of0.86 THz.

scholarly journals Association of Auditory Steady State Responses with Perception of Temporal Modulations and Speech in Noise

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Venugopal Manju ◽  
Kizhakke Kodiyath Gopika ◽  
Pitchai Muthu Arivudai Nambi
Keyword(s):  
Steady State ◽  
Speech Perception ◽  
Amplitude Modulation ◽  
Modulation Depth ◽  
Normal Hearing ◽  
Positive Correlation ◽  
Behavioral Method ◽  
Modulation Detection ◽  
Auditory Steady State Responses ◽  
40 Hz

Amplitude modulations in the speech convey important acoustic information for speech perception. Auditory steady state response (ASSR) is thought to be physiological correlate of amplitude modulation perception. Limited research is available exploring association between ASSR and modulation detection ability as well as speech perception. Correlation of modulation detection thresholds (MDT) and speech perception in noise with ASSR was investigated in twofold experiments. 30 normal hearing individuals and 11 normal hearing individuals within age range of 18–24 years participated in experiments 1 and 2, respectively. MDTs were measured using ASSR and behavioral method at 60 Hz, 80 Hz, and 120 Hz modulation frequencies in the first experiment. ASSR threshold was obtained by estimating the minimum modulation depth required to elicit ASSR (ASSR-MDT). There was a positive correlation between behavioral MDT and ASSR-MDT at all modulation frequencies. In the second experiment, ASSR for amplitude modulation (AM) sweeps at four different frequency ranges (30–40 Hz, 40–50 Hz, 50–60 Hz, and 60–70 Hz) was recorded. Speech recognition threshold in noise (SRTn) was estimated using staircase procedure. There was a positive correlation between amplitude of ASSR for AM sweep with frequency range of 30–40 Hz and SRTn. Results of the current study suggest that ASSR provides substantial information about temporal modulation and speech perception.

scholarly journals Resolving competing theories for control of the jamming avoidance response: the role of amplitude modulations in electric organ discharge decelerations

1999 ◽  
Vol 202 (10) ◽  
pp. 1377-1386 ◽  
Author(s):  
Y. Takizawa ◽  
G.J. Rose ◽  
M. Kawasaki
Keyword(s):  
Avoidance Response ◽  
Electric Fields ◽  
Phase Difference ◽  
Amplitude Modulation ◽  
Electric Organ Discharge ◽  
Modulation Depth ◽  
Electric Organ ◽  
Jamming Avoidance Response ◽  
Jamming Avoidance

The algorithm for the control of the jamming avoidance response (JAR) of Eigenmannia has been the subject of debate for over two decades. Two competing theories have been proposed to explain how fish determine the correct direction to shift their pacemaker frequency during jamming. One theory emphasizes the role of time-asymmetric beat envelopes, while the other emphasizes the role of amplitude- and phase-difference computations that arise from the differences in spatial geometry of the electric fields of neighboring fish. In repeating earlier experiments, we found that the decision to raise or lower the pacemaker frequency reliably above or below its resting level depends on the latter process, and that frequency deceleration responses to amplitude modulation appear to be sufficient to explain previous experimental results on which the former theory is based. Specifically, fish of the genus Eigenmannia show differential deceleration responses to asymmetric beat envelopes. The deceleration responses do not require phase modulation and show a sensitivity for amplitude modulation depth and selectivity for amplitude modulation rate comparable with that of JARs that are elicited when amplitude- and phase-difference information is available.

scholarly journals Age-related decline in behavioral discrimination of amplitude modulation frequencies compared to envelope-following responses

2017 ◽  
Author(s):  
Jesyin Lai ◽  
Edward L. Bartlett
Keyword(s):  
Amplitude Modulation ◽  
Speech Intelligibility ◽  
Modulation Depth ◽  
Acoustic Startle ◽  
Hearing Threshold ◽  
Auditory Brainstem ◽  
Acoustic Startle Reflex ◽  
Neural Activation ◽  
Age Related ◽  
Brainstem Response

AbstractThe ability to discriminate modulation frequencies is important for speech intelligibility because speech has amplitude and frequency modulations. Neurophysiological responses assessed by envelope following responses (EFRs) significantly decline at faster amplitude modulation frequencies (AMF) in older subjects. A typical assumption is that a decline in EFRs will necessarily result in corresponding perceptual deficits. To test this assumption, we investigated young and aged Fischer-344 rats’ behavioral AMF discrimination abilities and compared to their EFRs. A modified version of prepulse inhibition (PPI) of acoustic startle reflex (ASR) was used to obtain behavioral performance. A PPI trial contains pulses of sinusoidal AM (SAM) at 128 Hz presented sequentially, a SAM prepulse with different AMF and a startle-eliciting-stimulus. To account for hearing threshold shift or age-related synaptopathy, stimulus levels were presented at 10-dB lower or match to the aged peripheral neural activation (using auditory brainstem response wave I amplitude). When AMF differences and modulation depths were large, young and aged animals’ behavioral performances were comparable. Aged animals’ AMF discrimination abilities declined as the AMF difference or the modulation depth reduced, even compared to the young with peripheral matching. Young animals showed smaller relative decreases in EFRs with reduced modulation depths. The correlation of EFRs and AM perception was identified to be more consistent in young animals. The overall results revealed larger age-related deficits in behavioral perception compared to EFRs, suggesting additional factors that affect perception despite smaller degradation in neural responses. Hence, behavioral and physiological measurements are critical in unveiling a more complete picture on the auditory function.

scholarly journals Amplitude modulation depth discrimination in hearing‐impaired and normal‐hearing listeners

2008 ◽  
Vol 123 (5) ◽  
pp. 3859-3859
Author(s):  
Stephan D. Ewert ◽  
Jutta Volmer ◽  
Torsten Dau ◽  
Jesko Verhey
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Depth Discrimination
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