Songbirds use pulse tone register in two voices to generate low-frequency sound

The principal physical mechanism of sound generation is similar in songbirds and humans, despite large differences in their vocal organs. Whereas vocal fold dynamics in the human larynx are well characterized, the vibratory behaviour of the sound-generating labia in the songbird vocal organ, the syrinx, is unknown. We present the first high-speed video records of the intact syrinx during induced phonation. The syrinx of anaesthetized crows shows a vibration pattern of the labia similar to that of the human vocal fry register. Acoustic pulses result from short opening of the labia, and pulse generation alternates between the left and right sound sources. Spontaneously calling crows can also generate similar pulse characteristics with only one sound generator. Airflow recordings in zebra finches and starlings show that pulse tone sounds can be generated unilaterally, synchronously or by alternating between the two sides. Vocal fry-like dynamics therefore represent a common production mechanism for low-frequency sounds in songbirds. These results also illustrate that complex vibration patterns can emerge from the mechanical properties of the coupled sound generators in the syrinx. The use of vocal fry-like dynamics in the songbird syrinx extends the similarity to this unusual vocal register with mammalian sound production mechanisms.

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Low-frequency sound sources in high-speed turbulent jets

Journal of Fluid Mechanics ◽

10.1017/s0022112008004096 ◽

2008 ◽

Vol 617 ◽

pp. 231-253 ◽

Cited By ~ 33

Author(s):

DANIEL J. BODONY ◽

SANJIVA K. LELE

Keyword(s):

High Speed ◽

Low Frequency ◽

Turbulent Jets ◽

Acoustic Analogy ◽

Sound Sources ◽

Strongly Coupled ◽

Eddy Simulation ◽

Phase Cancellation ◽

Jet Velocity ◽

Two Jets

An analysis of the sound radiated by three turbulent, high-speed jets is conducted using Lighthill's acoustic analogy (Proc. R. Soc. Lond. A, vol. 211, 1952, p. 564). Computed by large eddy simulation the three jets operate at different conditions: a Mach 0.9 cold jet, a Mach 2.0 cold jet and a Mach 1.0 heated jet. The last two jets have the same jet velocity and differ only by temperature. None of the jets exhibit Mach wave characteristics. For these jets the comparison between the Lighthill-predicted sound and the directly computed sound is favourable for all jets and for the two angles (30° and 90°, measured from the downstream jet axis) considered. The momentum (ρuiuj) and the so-called entropy [p − p∞ − a∞2(ρ − ρ∞)] contributions are examined in the acoustic far field. It is found that significant phase cancellation exists between the momentum and entropy components. It is observed that for high-speed jets one cannot consider ρuiuj and (p′ − a∞2ρ′)δij as independent sources. In particular the ρ′ūxūx component of ρuiuj is strongly coupled with the entropy term as a consequence of compressibility and the high jet velocity and not because of a linear sound-generation mechanism. Further, in more usefully decoupling the momentum and entropic contributions, the decomposition of Tij due to Lilley (Tech. Rep. AGARD CP-131 1974) is preferred. Connections are made between the present results and the quieting of high-speed jets with heating.

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Connectors with assessed quality, for use in d.c., low-frequency analogue and in digital high-speed data applications

10.3403/01187454 ◽

1998 ◽

Keyword(s):

High Speed ◽

Low Frequency ◽

High Speed Data

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Connectors with assessed quality, for use in d.c., low-frequency analogue and in digital high speed data applications. Printed board connectors

10.3403/01484487 ◽

1998 ◽

Keyword(s):

High Speed ◽

Low Frequency ◽

High Speed Data

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Connectors with assessed quality, for use in d.c., low-frequency analogue and in digital high speed data applications

10.3403/02064996u ◽

2015 ◽

Keyword(s):

High Speed ◽

Low Frequency ◽

High Speed Data

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Connectors with assessed quality, for use in d.c., low-frequency analogue and in digital high speed data applications. Rectangular connectors

10.3403/02904133 ◽

2003 ◽

Keyword(s):

High Speed ◽

Low Frequency ◽

High Speed Data

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Research and Fabrication of Broadband Ring Flextensional Underwater Transducer

Sensors ◽

10.3390/s21041548 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1548

Author(s):

Jiuling Hu ◽

Lianjin Hong ◽

Lili Yin ◽

Yu Lan ◽

Hao Sun ◽

...

Keyword(s):

High Speed ◽

Structural Parameters ◽

Low Frequency ◽

Flexural Vibration ◽

Underwater Acoustic Communication ◽

Voltage Response ◽

Water Tank ◽

Spherical Cap ◽

Finite Element Software ◽

Underwater Transducer

At present, high-speed underwater acoustic communication requires underwater transducers with the characteristics of low frequency and broadband. The low-frequency transducers also are expected to be low-frequency directional for realization of point-to-point communication. In order to achieve the above targets, this paper proposes a new type of flextensional transducer which is constructed of double mosaic piezoelectric ceramic rings and spherical cap metal shells. The transducer realizes broadband transmission by means of the coupling between radial vibration of the piezoelectric rings and high-order flexural vibration of the spherical cap metal shells. The low-frequency directional transmission of the transducer is realized by using excitation signals with different amplitude and phase on two mosaic piezoelectric rings. The relationship between transmitting voltage response (TVR), resonance frequency and structural parameters of the transducer is analyzed by finite element software COMSOL. The broadband performance of the transducer is also optimized. On this basis, the low-frequency directivity of the transducer is further analyzed and the ratio of the excitation signals of the two piezoelectric rings is obtained. Finally, a prototype of the broadband ring flextensional underwater transducer is fabricated according to the results of simulation. The electroacoustic performance of the transducer is tested in an anechoic water tank. Experimental results show that the maximum TVR of the transducer is 147.2 dB and the operation bandwidth is 1.5–4 kHz, which means that the transducer has good low-frequency, broadband transmission capability. Meanwhile, cardioid directivity is obtained at 1.4 kHz and low-frequency directivity is realized.

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