  We report on measurements of the transverse fluctuations of a string in a
turbulent air jet flow. Harmonic modes are excited by the fluctuating drag
force, at different wave-numbers. This simple mechanical probe makes it
possible to measure excitations of the flow at specific scales, averaged over
space and time: it is a scale-resolved, global measurement. We also measure the
dissipation associated to the string motion, and we consider the ratio of the
fluctuations over dissipation (FDR). In an exploratory approach, we investigate
the concept of {\it effective temperature} defined through the FDR. We compare
our observations with other definitions of temperature in turbulence. From the
theory of Kolmogorov (1941), we derive the exponent -11/3 expected for the
spectrum of the fluctuations. This simple model and our experimental results
are in good agreement, over the range of wave-numbers, and Reynolds number
accessible ($74000 \leq Re \leq 170000$).
