Applying for a job is often an impersonal process. You're just a name on a screen or a piece of paper. Letting the potential employer hear your voice might help you get the job.
Photo by ScottieT812
A recent study published by Psychological Science compared perceptions of text versus voice presentations. When potential employers heard an applicant's voice, they rated the applicant better:
Evaluators rated the candidates as more competent, thoughtful, and intelligent when they heard the pitch than when they read it and, as a result, liked the candidate more and were more interested in hiring the candidate.
The experiment was done with actors and random adults, not professional managers, so this is hardly perfect proof -- but if you're gunning for a job, giving a hiring manager a call may not be such a bad idea. That might just give you an edge if things are competitive. (Obviously, if the ad or company policy says "no phone calls", then don't call.)
The Sound of Intellect: Speech Reveals a Thoughtful Mind, Increasing a Job Candidate's Appeal [Psychological Science via Science of Us]