PORTLAND, Ore. — The rich, deep voice reciting the Quran sounds like an imam leading prayers in a mosque. The cadence has a pulse of its own: prolonged syllables, followed by rippling shorter ones. Up the scale and down. It stops just short of music. The chant is smooth, reverent, prayerful.

And, suddenly, it stops.

“What page was I on?” asks Ahmed Mohammed, 14.

The high school student, wearing a green T-shirt, blue jeans and sneakers, is competing in the annual Quran memorization contest at the Muslim Educational Trust, a local Islamic community center. When a judge softly offers a number, Ahmed closes his eyes to envision the page and resumes his recitation. It will take him about an hour to finish chanting half of the Quran’s longest surah, or chapter — 144 verses.

When he leaves the room, he’s surrounded by other teenagers.

“How many mistakes?” a friend asks.

Ahmed shakes his head: Zero.

It’s hard to tell whether the nods in response signal skepticism or amazement. Similar exchanges happen dozens of times as 53 students, from first grade through high school, compete at six levels for cash prizes ranging from $30 to $150. But the prize money is of little consequence, students say.

They memorize the Quran because it’s the heart of their faith. And in a society that is sometimes skeptical of Islam, it’s important that Muslims know the contents of the Quran.

The Quran holds pride of place in the recent holy month of Ramadan, which commemorates the revelation of the sacred text. Islamic tradition holds that the angel Gabriel recited the Quran to the Prophet Muhammad over the course of 23 years and that he recited it, in turn, to his companions. For centuries, Muslims have believed that the best way to protect the integrity of their holy book is to memorize it exactly as they believe it was first recited.

Several judges for the contest have memorized all 114 surahs of the Quran, more than 6,000 verses. By comparison, the Hebrew Bible, or Old Testament, contains about 929 chapters, more than 23,000 verses. The New Testament includes 260 chapters, almost 8,000 verses.

Fatima AlBar, a doctoral student in engineering at Portland State University, began memorizing the Quran in her native Saudi Arabia. In 1999, she received an “ijazah,” an elaborate Arabic document that traces her recitation, taught and approved by her teacher, back to Muhammad.

AlBar estimates that only about 2,000 men and women in the world have such licenses. She values hers because it “preserves the chain.” She points out her name on the certificate and the 28 others who represent her scholarly lineage back to Muhammad. “The Prophet uttered these words,” she says, invoking a blessing on his name.

On a panel of judges, AlBar sat and listened intently, sometimes following along in the Quran and sometimes with her eyes closed. Occasionally, her mouth would form the words as students recited them. The panel of judges would gently stop a student if he or she had left out or transposed a phrase, a word, a single letter. If students were able to correct the error on their own, it did not count against them.

Judges also weighed pronunciation — the Arabic of the Quran is not always pronounced as modern Arabic is spoken — and the quality of the recitation: Is it reverent, steady, with pauses that do not break up a thought? Does it conform to accepted style, whether the surah is recited simply or in a heightened, prayerful tone?

On the other side of the center, younger students are reciting all 59 verses of the 44th surah, with its warning that earthly pride and power are humbled if they resist forces for good.

Ihsaan Ali, 8, stares straight ahead and recites from the surah with confidence and poise. One of her judges, Yasser Rasheed, holds a tiny, well-thumbed copy of the Quran in his hands. When he looks up and catches Ihsaan’s eye, she smiles but doesn’t stumble. When she finishes, he’s quick to say, “Good work.”

In another classroom, 15-year-old Sadio Ali recites the assigned surah softly, rarely looking up from her hands folded in her lap. When she makes a mistake, one judge shakes her head. Another suggests a place to start over. When Sadio seems flustered, Tahseen Mohammad, another judge who knows the Quran by heart, offers encouragement.

“You are doing excellent,” he says.

Sadio remembers her place, takes a deep breath and begins again.

(Nancy Haught writes for The Oregonian.)