A Certain Sound is an introduction to the theology and practice of preaching the gospel in public. The audiobook is concise, gracious, and uncompromising. It is saturated with Scripture, church history, and practical experience. It is a handbook and encouragement for open air preachers. It is an apologetic for frontline evangelism. It is written for both individuals and study groups, pastors and laymen, open air preachers and Christians who evangelize. He who has ears to hear, let him hear this audiobook!