Auditory nerve fibers’ thresholds correlate inversely with their spontaneous firing rates.

Evidence

As the amplitude of a stimulus is increased, the measured spike rate of a single auditory nerve fiber also tends to increase. To illustrate this, auditory nerve fiber behavior is often plotted using a rate-level function, which plots the neuron’s output firing rate as a function of the input stimulus level. … We observe a strong relationship between the firing rate of a neuron and the stimulus level. Using Figure 2–8, we also note that the threshold and SR of a neural fiber are related. The threshold of a neuron is defined as the lowest sound level that leads to a measureable increase in the driven spike rate. High spontaneous rate fibers have low thresholds, whereas low spontaneous fibers have high thresholds. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 235

For thresholdlevel stimuli, the only fibers available to code the vibration are the high-SR/low-threshold fibers. These are the only fibers that respond to sound levels below 20 dB SPL, and therefore are the only fibers active during threshold testing. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 256

Categorization

• DEFINE: Defines neural threshold as the lowest sound level producing a measurable increase in driven spike rate.
• corroborated: 2 independent passages support this claim — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 235; Jennifer Lentz, Psychoacoustics- Perception of Normal…, 256