<i>Acoustic Systems in Biology</i>

Fletcher, Neville H.; Fahey, P. F.

doi:10.1063/1.2808977

Cited by 124 publications

(213 citation statements)

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“…The resonant frequency of a bar is determined by structural attributes such as the bar's length, the second moment of inertia, Young's modulus and density of the constituent materials (Fletcher 1992). Whether measured in isolation or attached to the other secondaries, the structural properties of the sixth and seventh secondary feathers of M. deliciosus cause them to resonate near the fundamental frequency of the tone produced in nature.…”

Section: Discussionmentioning

confidence: 99%

“…Anatomical specializations of secondaries 6 and 7 in M. deliciosus may therefore be primarily associated with quality of the resonance in terms of the Q-value, rather than the location of the tuning in terms of frequency. Resonating feathers K. S. Bostwick et al 839 The Q-values for biological structures typically range from about 1 to 30 (Fletcher 1992), with resonance being broadly tuned for Q-values near 1, more sharply tuned for higher Q-values, and reasonably good resonators exhibiting at least Q . 5.…”

Section: Discussionmentioning

confidence: 99%

“…If a structure is excited at f 0 by a periodic driving force, it will vibrate with a relatively larger amplitude because the system stores vibrational energy (Rossing & Fletcher 1995). When damping (resistance to motion) is small, f 0 is approximately equal to the natural frequency of the system, which is the frequency of freely decaying vibrations (Fletcher 1992).…”

Section: (B) Stimulus and Response Experimentsmentioning

confidence: 99%

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Resonating feathers produce courtship song

et al. 2009

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Male Club-winged Manakins, Machaeropterus deliciosus (Aves: Pipridae), produce a sustained tonal sound with specialized wing feathers. The fundamental frequency of the sound produced in nature is approximately 1500 Hz and is hypothesized to result from excitation of resonance in the feathers' hypertrophied shafts. We used laser Doppler vibrometry to determine the resonant properties of male Club-winged Manakin's wing feathers, as well as those of two unspecialized manakin species. The modified wing feathers exhibit a response peak near 1500 Hz, and unusually high Q-values (a measure of resonant tuning) for biological objects (Q up to 27). The unmodified wing feathers of the Club-winged Manakin do not exhibit strong resonant properties when measured in isolation. However, when measured still attached to the modified feathers (nine feathers held adjacent by an intact ligament), they resonate together as a unit near 1500 Hz, and the wing produces a second harmonic of similar or greater amplitude than the fundamental. The feathers of the control species also exhibit resonant peaks around 1500 Hz, but these are significantly weaker, the wing does not resonate as a unit and no harmonics are produced. These results lend critical support to the resonant stridulation hypothesis of sound production in M. deliciosus.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: (B) Stimulus and Response Experimentsmentioning

confidence: 99%

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Resonating feathers produce courtship song

et al. 2009

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“…Assuming that the lizard ear is a two-input system, it can be modeled by a very simple lumped-element electrical analog (Fletcher 1992;Christensen-Dalsgaard and Manley 2005) consisting of the two sound inputs and three impedances: one for each tympanum (Z T ) and one for the buccal and mouth cavity (Z V ). Diffraction effects are neglected, so the two sound inputs (p 1 and p 2 ) differ only in phase by…”

Section: Modelmentioning

confidence: 99%

“…The circuit equation is Fletcher 1992), where U 1 is the volume velocity of one of the tympana, so U 1 divided by the tympanum area is the model vibration velocity of the tympanum.…”

Section: Modelmentioning

confidence: 99%

Acoustical Coupling of Lizard Eardrums

Christensen‐Dalsgaard

Manley

2008

JARO

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Lizard ears are clear examples of two-input pressuredifference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi-and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and indirect sound components on the eardrum. The ensuing pressure-difference characteristics generate the highest directionality of any similar-sized terrestrial vertebrate ear. The aim of the present study was to measure the gain of the direct and indirect sound components in three lizard species: Anolis sagrei and Basiliscus vittatus (iguanids) and Hemidactylus frenatus (gekkonid) by laser vibrometry, using either free-field sound or a headphone and coupler for stimulation. The directivity of the ear of these lizards is pronounced in the frequency range from 2 to 5 kHz. The directivity is ovoidal, asymmetrical across the midline, but largely symmetrical across the interaural axis (i.e., front-back). Occlusion of the contralateral ear abolishes the directionality. We stimulated the two eardrums with a coupler close to the eardrum to measure the gain of the sound pathways. Within the frequency range of maximal directionality, the interaural transmission gain (compared to sound arriving directly) is close to or even exceeds unity, indicating a pronounced acoustical transparency of the lizard head and resonances in the interaural cavities. Our results show that the directionality of the lizard ear is caused by the acoustic interaction of the two eardrums. The results can be largely explained by a simple acoustical model based on an electrical analog circuit.

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Vibration‐Energy‐Harvesting System: Transduction Mechanisms, Frequency Tuning Techniques, and Biomechanical Applications

Dong

Closson

Jin

et al. 2019

Adv Materials Technologies

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Vibration‐based energy‐harvesting technology, as an alternative power source, represents one of the most promising solutions to the problem of battery capacity limitations in wearable and implantable electronics, in particular implantable biomedical devices. Four primary energy transduction mechanisms are reviewed, namely piezoelectric, electromagnetic, electrostatic, and triboelectric mechanisms for vibration‐based energy harvesters. Through generic modeling and analyses, it is shown that various approaches can be used to tune the operation bandwidth to collect appreciable power. Recent progress in biomechanical energy harvesters is also shown by utilizing various types of motion from bodies and organs of humans and animals. To conclude, perspectives on next‐generation energy‐harvesting systems are given, whereby the ultimate intelligent, autonomous, and tunable energy harvesters will provide a new energy platform for electronics and wearable and implantable medical devices.

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Acoustic Systems in Biology

Cited by 124 publications

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Resonating feathers produce courtship song

Resonating feathers produce courtship song

Acoustical Coupling of Lizard Eardrums

Vibration‐Energy‐Harvesting System: Transduction Mechanisms, Frequency Tuning Techniques, and Biomechanical Applications

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