Objective: To determine whether the amplitude of the sound evoked triceps myogenic potential (SETMP) scales with the tonic force exerted by the muscle. Study design: A prospective study of myogenic potentials was conducted in 16 normal subjects. A monaural acoustic stimulus was presented to subjects while they while they exerted varying degrees of force with the triceps muscles. Subjects were required to activate the triceps by leaning into pressure transducers placed at shoulder height thereby

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... supporting their body weight. The unrectified myogenic potential was collected using response triggered averaging of the signal from surface electromyogram (EMG) electrodes placed over the triceps bilaterally. Setting: University affiliated otoneurology clinic. Patients: Sixteen healthy adult volunteers (8 females, 8 males), age ranging from age 17 to 57 years (mean 32 years). Main outcome measures: Latencies (msec) and amplitudes (µV) of the first two waves of the evoked response. Results : At 5, 10, 15 and 20 lbs. of force, the mean amplitudes of the ipsilateral SETMP responses were 27.32, 48.59, 56.35 and 106.41 µV, respectively, while the mean amplitudes of the contralateral SETMP responses were 48.42, 72.21, 72.67 and 111.25 µV, respectively. Conclusions: The amplitude of the SETMP response scales approximately linearly with the force of activation of the triceps muscle, and is fairly symmetrical.