Article 1 examining the sexual arousal in men, examination between imagery and auditory acts related to arousal.
Differ in genders: who really has a stronger desire towards sex?
Studies by Ellis & Symons suggest that it is more common that men focus on the physical aspects of sexuality more than women do. It is also known that men have twice as many fantasies, there is more focus on the details of sexual act and pleasure.

How important is imagery in relation to arousal?
Research by Geary, Vigil, & Byrd-Craven states that attractive images held within semantic memory and pattern matched with an auditory stimulus facilitate rapid arousal than unattractive images.
Although images do play a big role, in a study by smith it is reported that more vivid (realistic) visual images during sexual fantasy reported higher levels of sexual arousal but the content of imagery was separate from fantasy.
Heres an example: participants through a previous study by Geary, Vigil, & Byrd-Craven were asked to view erotic materials but instructed not to fantasize, these participants showed lower and slower mean levels of arousal responses, in comparison to those viewing erotic material while fantasizing.
Why ? the reason for the divison of imagery and fanstasy is that the formation of vivid or realistic mental images were the key factor for an individuals ability to become aroused during a sexual fantasy.
How this comes together: in a study by janssen he believes that there are two stages which fantasy sexual arousal