By Perry Phillips
For many of us, giving a talk to a room of just 40 or 50 people is a daunting task—even more so without a public address system.
Yet Jesus spoke outdoors to crowds 10 times that number. On one occasion, 5,000 men—not including women and children—heard him speak. He so captivated them that they didn’t think about eating (Matt 14:13–21; Mark 6:30–44; Luke 9:10–17; John 6:1–14). Shortly thereafter, 4,000 men, besides women and children, heard his teachings and witnessed his healings, again foregoing food (Matt 15:29–39; Mark 8:1–10).
How in the world could crowds so large hear and understand Jesus clearly enough to hang on his words for hours? He obviously had no sound system, nor did he pull his crowds into Greek or Roman theaters to take advantage of their acoustics. Yet thousands flocked to listen to his message.
How could he communicate to so many at once? As the Son of God, did he imprint his message directly on his listeners’ ears—a sonic miracle, perhaps? Hardly. One need not look to heavenly interventions; earthly explanations suffice.
THE PHYSICS OF SOUND AND THE PHYSIOLOGY OF THE BRAIN
Sounds surround us: pleasant music, shouts at a ballgame, incessant traffic, the annoying hum of a mosquito. All these sounds have one thing in common: they consist of vibrations (technically, pressure waves)1 that propagate through the air, impinge on our eardrums, and set off a chain of events by which our brains convert the vibrations into intelligible information.
Two basic factors govern the clarity by which one hears and understands a speaker: the strength of the speaker’s voice and the level of interference from ambient noise. Outdoor settings are intrinsically noisy, which demands that the speaker have a loud voice. How loud? Probably 75 decibels (db) and above, or about as loud as being in the same room with a vacuum cleaner. (Normal conversation registers 60 db.) George Whitefield, the 18th-century American evangelist, spoke to crowds estimated to number in the tens of thousands. His voice level could reach 90 db.2 Jesus spoke to many crowds, and like many outdoor speakers he surely possessed a very sturdy voice.
A robust voice, however, does not suffice. The listener must also filter the speech from the ambient noise—winnowing, as it were, intelligible wheat from cacophonous chaff. No doubt the crowds were noisy: people coming and going, internal chatting, fussy children, the wind rustling the grass, goats and sheep bleating in the background. The human brain, however, possesses an uncanny ability to focus on intelligible sounds in the midst of competing din. At the same time, the brain interpolates the message and fills in words or short phrases lost to surrounding commotion. The brain makes partial speech whole.
The above picture, however, is incomplete. One other very important factor remains: the surrounding terrain. But how does that help?
HOW THE TERRAIN AFFECTS OUTDOOR SPEECH
Jesus gave numerous speeches around the Sea of Galilee, and the region’s combination of hills, vales, and land ascending away from the shore provided natural amphitheaters for addressing large crowds.
This point was sufficiently proved by an experiment in the 1970s by lay archaeologist B. Cobbey Crisler and professional sound engineer Mark Miles.3 Crisler and Miles set up equipment at a cove on the shore of the Sea of Galilee near Tabgha, also near Capernaum. They chose this location to represent the setting where Jesus, pressed by the crowd, retreated to a boat and told the parable of the sower (Matt 13:1–9; Mark 4:1–9). Crisler and Miles did not use a boat, but a large rock protruding out of the water served the purpose.
To begin, Miles set up a sound generator on the rock, a little more than 30 feet (10 meters) offshore. The device emitted a “shrill, sustained tone” whose signal strength Miles measured while walking away from the shore along a couple lines centered on the rock and radiating outward at roughly a 30-degree angle. (Think of a thin slice of pie with its point at the rock and the rim on the shore.) The signal was clear all the way to a road about 300 feet (91 meters) away.
The second experiment involved Crisler standing on the rock and breaking balloons while Miles stood at various distances from the shore. Miles clearly detected the bursting balloons—as did everyone else passing along the road during the experiment.
Crisler and Miles initially embarked on investigating whether the natural terrain served as an auditorium with Jesus at the “stage” (the boat) and the crowd in the “seats” (the slopes). But Crisler and Miles unexpectedly found that the reverse also occurred: speech from the “seats” was clearly heard at the “stage.” Here’s how Crisler explains two examples involving cars:4
The first car was on its way to Capernaum. The passenger’s window was down. Suddenly and quite visibly to me on the rock, the car slowed. I couldn’t make out the faces from one hundred meters, but the voices were unmistakable. One said, ‘What’s he doing down there?’ The other answered, ‘I don’t know! He’s just standing there holding some balloons.’
The second car was on its way from Capernaum. The car did not slow perceptibly and it looked to me like there was only a driver. But there must have been a passenger as well, or the outburst I heard would have been even more remarkable. It was in German, a language I do not speak. But what I heard sounded completely comprehensible: “Ist ein Baloonist!”5
TOPOGRAPHY FOR TEACHING
The experiments by Crisler and Miles demonstrated that natural terrain can act as an outdoor auditorium. No doubt Jesus was aware of this and took advantage of natural features around the Sea of Galilee to speak to large crowds.
For example, the miracle of the feeding of the 5,000 took place somewhere around the city of Bethsaida (Luke 9:10). The feeding of the 4,000 occurred in the Decapolis (Mark 8:1–9; see 7:31). Both locations have excellent acoustical topography. In short, natural amphitheaters exist all along the shores of the Sea of Galilee, and Jesus used them as “public address systems” to teach the crowds.
Yes, the crowds had no problem hearing what Jesus said. But Jesus knew that hearing was not enough. One has to hear with the heart, not just with the ears.6 Note Jesus’ insistence on hearing in the parable of the sower: He begins the parable with “Listen; behold” (Mark 4:3) and ends with “If anyone has ears to hear, let him hear,” and “take care what you listen to” (4:23–24). How interesting that Jesus used the surrounding terrain both for acoustic enhancement and as an illustration of the receptivity of the human heart to his message.
This article is adapted from Perry G. Phillips, “Natural Amphitheaters Along the Sea of Galilee,” in Lexham Geographic Commentary on the Gospels, ed. Barry J. Beitzel (Bellingham: Lexham Press: 2017), 265–69. Scripture quotations are from the New American Standard Bible.