@article {57945,
	title = {Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations},
	year = {2013},
	abstract = {<p>The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency\&ndash;level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21\&plusmn;0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth\&rsquo;s tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the\&nbsp;moth ear, but also suggests a complex mechanical role for the rest of the transparent zone.</p>
},
	keywords = {Audiogram, DPOAE, Empyreuma pugione, laser Doppler vibrometry, mechanical tuning, moth},
	doi = {10.1242/jeb.085902},
	url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.085902https://syndication.highwire.org/content/doi/10.1242/jeb.085902},
	author = {Mora, E. C. and Cobo-Cuan, A. and Macias-Escriva, F. and Perez, M. and Nowotny, M. and Kossl, M.}
}
@article {57665,
	title = {Mechanical filtering for narrow-band hearing in the weta},
	year = {2011},
	abstract = {<p>This paper constitutes a major attempt to associate tympanic deflections with the mechanoreceptor organ location in an acoustic insect. The New Zealand tree weta (Hemideina thoracica) has tympanal ears located on each of the prothoracic tibiae. The tympana exhibit a sclerotized oval plate, membranous processes bulging out from the tibial cuticle and many loosely suspended ripples. We used microscanning laser Doppler vibrometry to determine how such a tympanal membrane vibrates in response to sound and whether the sclerotized region plays a role in hearing. The tympanum displays a single resonance at the calling frequency of the male, an unusual example of an insect tympana acting as a narrow bandpass filter. Both tympana resonate in phase with the stimulus and with each other. Histological sections show that the tympanal area is divided into two distinct regions, as in other ensiferans. An oval plate lies in the middle of a thickened region and is surrounded by a transparent and uniformly thin region. It is hinged dorsally to the tympanal rim and thus resembles the model of a \&lsquo;hinged flap\&rsquo;. The thickened region appears to act as a damping mass on the oscillation of the thin region, and vibration displacement is reduced in this area. The thinner area vibrates with higher amplitude, inducing mechanical pressure on the dorsal area adjacent to the crista acustica. We present a new model showing how the thickened region might confer a mechanical gain onto the activation of the crista acustica sensory neurons during the sound-induced oscillations.</p>
},
	keywords = {ensiferan ear, laser vibrometry, mechanical tuning, tympanum vibration, weta},
	doi = {10.1242/jeb.050187},
	url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.050187https://syndication.highwire.org/content/doi/10.1242/jeb.050187},
	author = {Lomas, K. and Montealegre-Z, F. and Parsons, S. and Field, L. H. and Daniel Robert}
}
