Nasr Ahmed started delivering the predawn call to prayer at his local mosque in 1947, when he was just a sprightly lad of 10 who loved to play ball in the streets.
Now he hobbles those same narrow lanes stroking a thick gray beard, but he's still known for the robust, clear voice that has awoken the Muslim faithful in his teeming neighborhood for more than a half-century. Perhaps not for much longer, though.
The city government is finalizing plans - first announced last September - to wire Cairo's 3,500 mosques so they will broadcast a live, unified call to prayer that would replace the chaotic cacophony which now bursts forth five times a day, amplified in some places through squeaky speakers.
What would seem to be a simple, modern solution to the din is upsetting both traditionalists and those who see it violating the spirit of more open expression emerging in the region.
The Ministry of Religious Endowments, which oversees public issues of worship, says it's responding to a flood of complaints about high noise levels, especially in tightly populated areas, and argues that it's up to the mosque to set a standard for greater order in this tumultuous megalopolis of 15 million.
But in one of the world's noisiest cities, where incessant honking is deemed vital to pilot a vehicle, and where piling friends and family into a riverboat thumping with music is considered fun, the idea that orderliness might be closer to godliness falls on very deaf ears indeed.
"This plan is haram," declares Mr. Ahmed, using the same Arabic word for 'forbidden' that's slapped on pork products and alcohol. "How can you try to stop something that God has called for?"
The wording of the calls is set, but the way each is sung - melodious or strident - sets a tone for the mosque.
Cairo's government has produced senior religious leaders to reassure people that the plan does not contravene Islamic law, but many Egyptians spot a sinister conspiracy, backed by Washington, to stifle the voices of more conservative religious leaders.
The US government has pressured Cairo on various issues of religious reform, arguing for example that textbooks in many of the country's mosque-backed institutions teach anti-Western principles. But officials here insist there's no nudging from Washington behind this effort, and say the radio broadcasts will feature a revolving group of religious leaders, who will offer a range of religious viewpoints.
But at least one conservative imam has argued that "technologizing" the call to prayer will start the nation down an ungodly path that will one day terminate with people bowing down before TV sets tuned to pictures of Mecca.
Officials point out that many Islamic countries, including Turkey, Jordan, and Yemen unified their calls to prayer years ago, and Muslims there have continued to perform their duty.
But coming as it does at a time when the entire Arab region seems to be taking a tentative step toward greater openness, the bid to unify the call to prayer seems inconsistent to many here.
"Just like every mosque has a different minaret, every mosque has a different voice," says Ashraf, who like many interviewed for this story would not to give his full name.
He works out of the Al Ghuri mosque in Cairo's old city, which has serviced the local community from behind towering ramparts for more than 500 years.
"The call to prayer has always come from here," he says, gesturing to the delicate Mameluk-era minaret, these days slung with a large loudspeaker. "The people won't accept any other way."
But a few independent voices have risen up in support of the government plan.
"The call to prayer, when I first heard it as a child, was beautiful to hear. It wafted over the city in soft and sometimes musical tones," wrote activist Nawal El-Saadawi in the Al Ahram Weekly. "Now it has become a cacophony of strident voices, a threatening call shot through with violence."
Mahmoud Hamdy Zaqzouq, the minister in charge of religious affairs, says he's trying to protect a sizable population here that quietly views the current state of affairs as more rowdy ruckus than religious freedom.
"Everyday I receive complaints from people about the loudspeakers and when I ask them to make official complaints, they say they are afraid of being accused of being infidels," he told the BBC.
Analysts and historians point out that Egyptian authorities have long run into trouble when they tried to regulate religion, and noted that few efforts through the ages to make Cairo less noisy and chaotic have met with success.
"They can't even organize traffic in Midan Tahrir," says political analyst Walid Kazziha, referring to Cairo's congested downtown plaza. "How do they think they are going to regulate the mosques?"
Some argue that a simpler plan might just be to ban amplifiers, and return to the way muezzins called the faithful to prayer in the prophet's day, using just their unamplified voices.
"Won't work any more," harrumphs Mr. Ahmed, who began calling prayers long before his local mosque had a loudspeaker. "Back then they did not have tall buildings and cars. Nowadays, we just have to be louder."