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a needle that acts when the auditor speaks and does nothing the rest of the time. (EMD, p. 42)
- it is a total uniform speed. There is not the faintest tick in it. There is not the faintest speed-up. There is nothing. It is just like molasses pouring out of the barrel - and there it is, and that's a clean needle. (SH Spec 224, 6212C13)
- one which flows, producing no pattern or erratic motions of the smallest kind with the auditor sitting looking at it and doing nothing. A clean needle is not just something that doesn't react to a particular question. It's a lovely slow flow, usually a rise, most beautifully expressed on a Mark V at 64 sensitivity. (HCOB 30 Dec 62)