AM voice
Ordinary voice or music sent with amplitude modulation, the oldest way of putting sound on radio.
What does it sound like?
Normal-sounding speech or music, often with background hiss and fading on shortwave.
Who uses it?
Broadcast stations (the AM band and shortwave), aircraft talking to controllers, and some hams.
Where and when can I hear it?
The AM broadcast band (530-1700 kHz), shortwave broadcasters between about 2.3 and 26 MHz, and aircraft voice on 118-137 MHz.
Hear it live
- Northern Utah WebSDR #1 (Northern Utah, USA) · 7,290 kHz AM
W1AW's voice bulletin, weekdays at 9:45 p.m. US Eastern time; 7.290 MHz is sent in full-carrier AM. W1AW is in Connecticut, so it may be weak or absent at this receiver.
These are free public receivers run by other people; we only link to them. You'll hear the signal only if it's on the air right now and conditions carry it to that receiver, so if it's quiet, try another time. Links last reviewed 2026-09-28.
The science
In amplitude modulation the transmitter sends a steady carrier wave and makes its strength rise and fall in step with the sound. That produces two mirror-image copies of the audio, called sidebands, one just above and one just below the carrier, so the signal is about twice as wide as the audio it carries. In the United States, AM broadcast stations sit on 117 channels spaced 10 kHz apart, from 540 to 1700 kHz.
Why use it?
AM is the simplest kind of voice radio to receive: almost any detector that follows the signal's strength will recover the sound, which is why the earliest and cheapest radios could play it. Stations on the AM band also reach much farther at night, when their signals bounce off the ionosphere as skywave. The price is inefficiency, since the carrier itself carries none of the sound.
Lore
Westinghouse station KDKA in Pittsburgh began scheduled programming on November 2, 1920, with the Harding-Cox presidential election returns, and is recognized as a pioneer of commercial broadcasting. It grew out of engineer Frank Conrad's experimental station, 8XK.
Easily confused with
- Single-sideband voice (SSB), from the same family
- Narrow FM voice, from the same family
- FM broadcast, from the same family