Biomedical subjects

A C Pinder

Publications and source records attributed to A C Pinder.

21 records · Page 2Linked to original sources

PubMed1985

Acoustic vibration of the amphibian eardrum studied by white noise analysis and holographic interferometry.

The motion of the amphibian eardrum under free-field acoustic stimulation was investigated using time-averaged holography. We show that the amplitude is linearly related to sound pressure up to +/- 1000 nm. The frequency response of the eardrum shows broad resonance characteristics with a main peak between 1200-2200 Hz. The velocity of the tympanic membrane's motion at its resonance frequency matches the acoustic velocity of air particles. The resonance characteristics of the eardrum are also revealed by white noise stimulation. The power spectrum obtained by Fourier transformation of the autocorrelation of the response to noise resembles closely that obtained by holography.

Acoustic Stimulation↗

PubMed1984

The directionality of the frog ear described by a mechanical model.

The frog ear can be modelled as two coupled eardrums with an additional sound pathway through the mouth cavity. In a previous version of this model, with realistic parameters, we were able to account very well for empirical measurements of the eardrum vibration under free- and closed-field acoustic conditions. This earlier model does not, however, adequately predict the directional characteristics of the frog ear as determined empirically. In this paper we present a modified model which will account for the directionality together with the free- and closed-field frequency responses, and which is also consistent with anatomical considerations.

Animals↗

PubMed1983

Mechanical properties of the frog ear: vibration measurements under free- and closed-field acoustic conditions.

The acoustically induced motion of the eardrum of the frog was measured by an incoherent optical technique. When free-field sound stimulation was used, the eardrum vibration had a band-pass characteristic with maximum amplitude at 1-2.5 kHz. However, when the sound was presented in a closed-field acoustic coupler the response was low-pass (cut-off frequency about 2.5 kHz). We demonstrate that the motion is the result of the mechanical properties of the eardrum and the sound pressure acting upon it. The net pressure is due to a combination of sound incident directly on the front of the drum and of sound conducted to the rear via internal (resonant) pathways. The frog ear therefore acts as a pressure-gradient receiver at low frequency and a pressure receiver at high frequency. A model is proposed and analysed in terms of its electrical analogue. This model accounts for both our own experimental observations and those of previous studies.

Animals↗