The aims of this study were to characterize the pattern of voluntary activity of young rats in response to resistance loading on running wheels and to determine the effects of the activity on the growth of six limb skeletal muscles. Male Sprague-Dawley rats (4 weeks old) were housed individually with a resistance running wheel (R-RUN, n = 7) or a conventional free-spinning running wheel (F-RUN, n = 6) or without a wheel, as non-running control animals (CON, n = 6). The torque required to move the wheel in the R-RUN group was progressively increased, and the activity (velocity, distance and duration of each bout) of the two running wheel groups was recorded continuously for 45 days. The R-RUN group performed many more, shorter and faster bouts of running than the F-RUN group, yet the mean daily distance was not different between the F-RUN (1.3 ± 0.2 km) and R-RUN group (1.4 ± 0.6 km). Only the R-RUN resulted in a significantly (P < 0.05) enhanced muscle wet mass, relative to the increase in body mass, of the plantaris (23%) and vastus lateralis muscle (17%), and the plantaris muscle fibre crosssectional area, compared with CON. Both F-RUN and R-RUN led to a significantly greater wet mass relative to increase in body mass and muscle fibre cross-sectional area in the soleus muscle compared with CON. We conclude that the pattern of voluntary activity on a resistance running wheel differs from that on a free-spinning running wheel and provides a suitable model to induce physiological muscle hypertrophy in rats.

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The landline and mobile phone networks are very different in the manner in which they handle and process the speech signal, with consequential differences in their impact on the speech spectrum as well as on the acoustic parameters of interest in the forensic arena. This paper overviews the key features of both networks which give rise to these differences. Some findings are then presented showing the impact of the mobile network on fundamental frequency, F0, as well as on the first three formants in vowel sounds. It is shown that though the impact on F0 is not great, the impact on the formant frequencies, and particularly on the measurements of these determined using automated formant trackers, can be significant. These early findings are considered to be of great importance to forensic practitioners relying on acoustic measurements as part of their investigations.

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The acoustical characteristics of a room are traditionally determined using omnidirectional impulse response measurements, yielding information about sound reflections in terms of magnitude and time, but not direction. However, the direction of reflections is often important, and thus the need for a practical, low cost measurement system for determining this. In this paper we present the performance of a low cost measurement system utilising an inexpensive microphone array, namely the Core Sound TetraMic, for the determination of 3D room impulse responses. These can then be visualised, for example, as a "hedgehog pattern". Experiments undertaken in an anechoic chamber indicate that the accuracy of directional estimation of this system is in the region of ± 7.5°.

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