Purpose: Low-frequency detection thresholds in quiet vary across transducers. This experiment tested the hypothesis that transducer effects are larger in young children than adults, due to higher levels of self-generated noise in children. Method: Listeners were normal-hearing 4.6- to 11.7-year-olds and adults. Warble-tone detection was measured at 125, 250, 500, and 1000 Hz with a sound-field speaker, insert earphones, and supra-aural headphones. Probe microphone recordings measured self-generated noise levels. Results: Thresholds were similar across ages for speaker measurements. Transducer effects were larger for children than adults, with mean child--adult threshold differences at 125 Hz of 3.4 dB (insert earphones) and 6.6 dB (supra-aural headphones). Age effects on threshold were broadly consistent with noise levels measured in the ear canal. Conclusions: Self-generated noise appears to elevate children's low-frequency thresholds measured with occluding transducers. These effects could be particularly relevant to the diagnosis of minimal and mild hearing loss in children.