The Physics of Being Heard: Why Personal Alarm Decibel Ratings Don't Mean What Buyers Think

TAMPA, Fla. - Aug. 10, 2026 - PRLog -- Nearly every personal alarm sold in the United States prints the same number on its package: 130 decibels. No federal agency verifies it. No industry standard defines how it is measured, at what distance, on what battery, or at what point in that battery's life.

David Happe spent years inside that category. He built a top-selling personal alarm brand named Vigilant, sold it to Mace, and served as an executive there. He has now published something the industry has never volunteered: an unedited video of a decibel meter running beside his own product, reading 133 dB at source and sustained for the full 50-minute runtime of his new brand, Resonant.

The distance between that number and what most alarms actually produce is far wider than it appears, because decibels are logarithmic. Every 10 dB represents roughly ten times the acoustic intensity and about double the perceived loudness to the human ear. Distance compounds it. Sound pressure falls about 6 dB with every doubling of distance from the source, so a 20 dB deficit costs an alarm roughly ninety percent of its effective range. Ambient noise closes what is left. A busy street or a parking garage runs 70 to 85 dB, and a weak alarm drops below that floor long before a listener would describe it as silent.

"You press the button in the store, you hear something loud, and you file it away as working," Happe said. "Nobody is standing in the aisle with a sound level meter, and nobody is calculating inverse square falloff during an emergency."

Most decibel claims in the category are peak readings, captured the instant a siren fires on a fresh cell. Sustained output is the harder problem, and Happe argues it is where the category fails. The button cell batteries powering most personal alarms hold very little energy and their voltage sags under load as they deplete. The device does not stop working. It gets quieter, month by month, with no low-battery indicator on a product the owner never switches on.

"An alarm that fades is worse than an alarm that dies, because a dead alarm at least tells you the truth," Happe said.

Happe has published the full engineering analysis, including the decibel meter test video and the reasoning behind Resonant's standard AAA power system, at:

https://pepperspraywarehouse.com/blogs/fight-back/personal-alarms-using-button-batteries-will-get-quiet-before-they-stop-working-entirely

About:  Resonant™ personal alarms are engineered for sustained acoustic output and long-term standby reliability. Resonant™ Personal Alarms. You Will Be Heard.