scholarly journals Keeping returns optimal: gain control exerted through sensitivity adjustments in the harbour porpoise auditory system

2012 ◽  
Vol 279 (1736) ◽  
pp. 2237-2245 ◽  
Author(s):  
Meike Linnenschmidt ◽  
Kristian Beedholm ◽  
Magnus Wahlberg ◽  
Jakob Højer-Kristensen ◽  
Paul E. Nachtigall
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Energy Levels ◽  
Gain Control ◽  
Auditory Brainstem ◽  
Sound Level ◽  
Harbour Porpoise ◽  
Fourth Power ◽  
Target Range ◽  
Brainstem Response

Animals that use echolocation (biosonar) listen to acoustic signals with a large range of intensities, because echo levels vary with the fourth power of the animal's distance to the target. In man-made sonar, engineers apply automatic gain control to stabilize the echo energy levels, thereby rendering them independent of distance to the target. Both toothed whales and bats vary the level of their echolocation clicks to compensate for the distance-related energy loss. By monitoring the auditory brainstem response (ABR) during a psychophysical task, we found that a harbour porpoise ( Phocoena phocoena ), in addition to adjusting the sound level of the outgoing signals up to 5.4 dB, also reduces its ABR threshold by 6 dB when the target distance doubles. This self-induced threshold shift increases the dynamic range of the biosonar system and compensates for half of the variation of energy that is caused by changes in the distance to the target. In combination with an increased source level as a function of target range, this helps the porpoise to maintain a stable echo-evoked ABR amplitude irrespective of target range, and is therefore probably an important tool enabling porpoises to efficiently analyse and classify received echoes.

scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals 14.85 µW Analog Front-End for Photoplethysmography Acquisition with 142-dBΩ Gain and 64.2-pArms Noise

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 512
Author(s):  
Binghui Lin ◽  
Mohamed Atef ◽  
Guoxing Wang
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Low Noise ◽  
Total Power ◽  
Cmos Process ◽  
Control Block ◽  
Silicon Area ◽  
Front End ◽  
Analog Front End

A low-power, high-gain, and low-noise analog front-end (AFE) for wearable photoplethysmography (PPG) acquisition systems is designed and fabricated in a 0.35 μm CMOS process. A high transimpedance gain of 142 dBΩ and a low input-referred noise of only 64.2 pArms was achieved. A Sub-Hz filter was integrated using a pseudo resistor, resulting in a small silicon area. To mitigate the saturation problem caused by background light (BGL), a BGL cancellation loop and a new simple automatic gain control block are used to enhance the dynamic range and improve the linearity of the AFE. The measurement results show that a DC photocurrent component up-to-10 μA can be rejected and the PPG output swing can reach 1.42 Vpp at THD < 1%. The chip consumes a total power of 14.85 μW using a single 3.3-V power supply. In this work, the small area and efficiently integrated blocks were used to implement the PPG AFE and the silicon area is minimized to 0.8 mm × 0.8 mm.

Hearing thresholds of small native Australian mammals – red-tailed phascogale (Phascogale calura), kultarr (Antechinomys laniger) and spinifex hopping-mouse (Notomys alexis)

2020 ◽  
Vol 190 (1) ◽  
pp. 342-351 ◽  
Author(s):  
Julie M Old ◽  
Carl Parsons ◽  
Melissa L Tulk
Keyword(s):  
Sound Pressure ◽  
Dynamic Range ◽  
Auditory Brainstem ◽  
Natural Environments ◽  
Predator Detection ◽  
Future Studies ◽  
Hearing Thresholds ◽  
Brainstem Response ◽  
Hearing Range ◽  
High Range

Abstract Hearing is essential for communication, to locate prey and to avoid predators. We addressed the paucity of information regarding hearing in Australian native mammals by specifically assessing the hearing range and sensitivity of the red-tailed phascogale (Phascogale calura), the kultarr (Antechinomys laniger) and the spinifex hopping-mouse (Notomys alexis). Auditory brainstem response (ABR) audiograms were used to estimate hearing thresholds within the range of 1–84 kHz, over a dynamic range of 0–80 dB sound pressure level (SPL). Phascogales had a hearing range of 1–40 kHz, kultarrs 1–35 kHz and hopping-mice 1–35 kHz, with a dynamic range of 17–59 dB SPL, 20–80 dB SPL and 30–73 dB SPL, respectively. Hearing for all species was most sensitive at 8 kHz. Age showed no influence on optimal hearing, but younger animals had more diverse optimal hearing frequencies. There was a relationship between males and their optimal hearing frequency, and greater interaural distances of individual males may be related to optimal hearing frequency. Because nocturnal animals use high-range hearing for prey or predator detection, our study suggests this may also be the case for the species examined in this study. Future studies should investigate their vocalizations and behaviour in their natural environments, and by exposing them to different auditory stimuli.

Bone conduction auditory brainstem responses in infants

2004 ◽  
Vol 118 (2) ◽  
pp. 117-122 ◽  
Author(s):  
P. E. Campbell ◽  
C. M. Harris ◽  
S. Hendricks ◽  
T. Sirimanna
Keyword(s):  
Hearing Loss ◽  
Dynamic Range ◽  
Bone Conduction ◽  
Low Frequency ◽  
Paediatric Population ◽  
Auditory Brainstem ◽  
Sensorineural Hearing ◽  
Auditory Brainstem Responses ◽  
Brainstem Response ◽  
Narrow Dynamic Range

The contribution of air conduction auditory brainstem response (AC-ABR) testing in the paediatric population is widely accepted in clinical audiology. However, this does not allow for differentiation between conductive and sensorineural hearing loss. The purpose ofthis paper is to review the role of bone conduction auditory brainstem responses (BC-ABR). It is argued that despite such technical difficulties as a narrow dynamic range, masking dilemmas, stimulus artifact and low frequency underestimation of hearing loss, considerable evidence exists to suggest that BC-ABR testing provides an important contribution in the accurate assessmentof hearing loss in infants. Modification of the BC-ABR protocol is discussed and the technical difficulties that may arise are addressed, permitting BC-ABR to be used as a tool in the differential diagnosis between conductive and sensorineural hearing. Two relevant case studies are presented to highlight the growing importance of appropriate management in early identification of hearing loss. It can be concluded that BC-ABR should be adopted as a routine clinical diagnostic tool.

An Optimized Design Strategy for the Hardware Implementation of the Hearing Aid Algorithms

2015 ◽  
Vol 719-720 ◽  
pp. 548-553
Author(s):  
Feng Guo ◽  
Shan Shan Yong ◽  
Zhao Yang Guo ◽  
Xin An Wang ◽  
Guo Xin Zhang
Keyword(s):  
Hardware Implementation ◽  
Dynamic Range ◽  
Automatic Gain Control ◽  
Hearing Aid ◽  
Gain Control ◽  
Design Strategy ◽  
Optimized Design ◽  
Wide Dynamic Range ◽  
Dynamic Range Compression ◽  
The Common

In this paper, a new design strategy for the hardware implementation of hearing aid algorithms is proposed. Two familiar hearing aid algorithms—Wide Dynamic Range Compression (WDRC) and Automatic Gain Control (AGC)—are implemented in one circuit as an example. By putting the common arithmetic procedures into common module, the operation units can be used repeatedly. In this way, the area and power consumption are visibly reduced.

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