Understanding speech in noise is a challenging task. Moreover, the ability to understand speech in background noise varies considerably from person to person, even for people that have normal audiograms and hence no measurable hearing loss. This variability may result from cochlear synaptopathy, also referred to as hidden hearing loss, as well as from damage to the neural pathways in the brainstem and in the central nervous system that are responsible for sound processing. Here we describe our recent work on speech-evoked activity in the auditory brainstem and its relation to speech-in-noise comprehension. In particular, we show how the neural tracking of the pitch of continuous speech in the auditory brainstem can be measured from scalp electrodes. Moreover, we show that this neural tracking is modulated by selective attention, and that there is considerable variation in the strength of the attentional modulation between subjects. We do not find evidence that this variability is related to hidden hearing loss. However, we show that the attentional modulation of the speech-evoked brainstem activity can partly explain a subject's ability to understand speech in noise.