Multisensory processing in the brain is pivotal for forming perceptual decisions. While the primary sensory areas were traditionally considered strictly unisensory, recent rodent research has unveiled significant interactions between the auditory and visual cortices. Notably, V1 neurons were found to be hyperpolarized by auditory noise bursts or show sensitivity to the temporal coherence of audiovisual stimuli. These findings indicate that primary sensory regions possess the computational capacity for multisensory processing, although the impact of such cross-modal interactions on decision-making remains elusive. To explore this further, we trained 10 rats in a visual temporal frequency (TF) classification task, coupling visual stimuli with sensorily salient, yet task-irrelevant auditory stimuli, to examine the spontaneous, ‘unsupervised’ impact of auditory information on visual perception. Sounds were fixed-, null-amplitude, or amplitude-modulated (AM), allowing to test two hypotheses: whether the perception of periodic visual stimuli could be affected by temporally congruent or incongruent auditory stimuli; and whether sound power spontaneously affects visual perception accordingly. Our results indicated that while the temporal coherence between audiovisual stimuli did not modulate visual perception, the power of auditory stimuli significantly influenced rats' performance, leading to an overestimation of visual TFs inversely related to sound intensity. We proposed that sound power modulates the gain of the visual TF sensory encoding, and encapsulated this hypothesis into a Bayesian model that precisely predicted the animals' behavior. These findings suggest the role of early audiovisual interactions in perceptual decisions, emphasizing the influence of auditory stimulus power in shaping visual perception.