Taos: The Hum No One Could Find

Steve Walters woke at about four in the morning with an engine still running in his ears.

He had dreamed that a car was idling outside his bedroom window. Awake, he could still hear it. The musician went through his house near Taos, New Mexico, looking for the source. He turned off the circuit breakers. The sound remained. In a June 1993 interview, Walters said he then recognized the noise people around town had been discussing.

They called it the Taos Hum. For some it was a low throb like distant machinery; for others, it had a hiss or a higher whine alongside it. Many neighbours heard nothing at all. But for those who did, the sound could outlast a night’s sleep, a search through the house, and the simple test of switching the power off.

When the silence changed

Bob and Catanya Saltzman traced their own experience back to the spring of 1991. Catanya told an Associated Press reporter in 1993 that she first noticed the sound in May; her husband began hearing it about two weeks later. They described a grinding pulse with a whine above it. Both were troubled by the loss of quiet in their home outside Taos.

At first, a sound heard inside a house invites a household explanation. K.C. Grams, another resident interviewed by the AP, initially looked for a source in her adobe home. Later she heard it while camping roughly thirty miles away. Her experience had moved with her, but she still had no name for it until a stranger at a school gathering asked whether she, too, heard a hum. For Grams, the question itself mattered: someone else recognized what she had been trying to describe.

Catanya Saltzman put her experience into a letter to the Taos News in March 1992. Other residents began contacting the couple. The Saltzmans circulated an informal questionnaire, wrote to officials and spoke at public meetings. These steps did not establish that everyone heard one physical sound. They turned private experiences into a local problem that could be counted, compared and investigated.

Walters, a guitarist and music teacher, came to his own recognition later. He had moved from Portland in search of quiet. The Washington Post recorded his account after the night when his dream of an idling car continued into waking. The search through his home gave him a scene he could describe, but it left the source as elusive as it had been for the Saltzmans and Grams.

A team comes to Taos

The residents’ appeals reached New Mexico’s congressional delegation. In 1993, a request for an investigation brought together researchers from the University of New Mexico, Sandia and Los Alamos national laboratories, and the Air Force’s Phillips Laboratory. Mechanical engineer Joe Mullins coordinated the team; hearing scientist James Kelly joined to examine what listeners were perceiving. Their account, published by the Acoustical Society of America in 1995, describes a public inquiry shaped in part by residents’ concern that a government installation might be involved.

The team first listened to the people who heard the hum. Their descriptions were related but not identical. The sound seemed persistent to most of them, low in pitch, and often most noticeable when the surroundings were otherwise quiet. The investigators wanted more than comparisons with distant engines. They needed to know what frequencies listeners chose when given an actual sound to adjust.

In a guesthouse bedroom near the Saltzmans’ home, they set up equipment that could produce a low tone. Ten hearers took part in matching tests. Eight were able to select a generated sound that matched what they were perceiving, and the researchers reported that the choices were reproducible. The selected carrier frequencies stretched from 32 to 80 hertz. The perceived pulses were slower, from about half a cycle to two cycles per second.

That experiment gave the team numbers to investigate. It also showed that the hum was not one identical note chosen by everyone. Each hearer could point to a sound resembling their own experience, yet the matches varied across the group.

The big ear

The researchers built an unusually sensitive low-frequency microphone from an eighteen-inch woofer. In its enclosure it weighed more than 150 pounds, with recording and analysis equipment housed in a vehicle some distance away. The team took measurements at the Saltzmans’ rural home and at the Taos golf course, and used other instruments at further sites around the area.

Here, the investigation crossed from reported sound into measured air movement. A microphone could record a low-frequency wave whether or not the person beside it knew where that wave came from. If a common external sound was filling homes across the region, the team hoped to find its signature and follow it.

The records did contain ordinary background noise. A strong component around the electrical grid’s 60-hertz frequency initially looked promising. But hearers reported an especially strong hum at a remote site near Tres Piedras where the investigators found little of that electrical component. The apparent lead did not travel with the experience.

The team checked other paths. Magnetometers detected Schumann resonances, naturally occurring electromagnetic patterns, but the amplitudes looked normal. Geophones recorded ordinary background movement; one conspicuous event proved to be a gopher working near an instrument. The electromagnetic survey found signals attributable to power lines, local noise and known transmitters. The researchers also examined the frequency band used by Navy extremely low frequency communications, which some residents suspected, without finding a matching signal above the noise.

Their instruments were not silent. They simply did not reveal a sound, vibration or transmission that could account for what the hearers described.

The questionnaire

Alongside the fieldwork, the team mailed survey forms to 8,000 residents of Taos and surrounding communities, including Ranchos de Taos, Tres Piedras, Questa, Eagle Nest and Peñasco. They received 1,440 responses. Of those, 161 respondents were classified as hearers.

The figures gave the problem a shape beyond the handful of people who had come forward publicly. In the researchers’ later account, most classified hearers noticed the hum at least weekly. A majority said they perceived it most often between eight at night and nine in the morning. Nearly one in five said they could hear it more than fifty miles from Taos.

Mullins and Kelly described roughly two percent as a lower-bound estimate for the population surveyed, assuming all hearers answered the mailing. It was not a direct measurement showing that exactly two percent of Taos residents heard a single sound. The 161 classified hearers were real survey responses; the step from those responses to population prevalence depended on who did and did not return the form.

For the investigation, the survey mattered in another way. It showed that the perceived hum crossed households, ages and locations, while its timing and pitch were not perfectly shared. A source had to fit both sides of that pattern: the likenesses that let people recognize one another’s experience, and the differences that appeared when they tried to measure it.

Looking closer to the listener

By late August 1993, the team had reported no unusual acoustic, seismic or electromagnetic signal that explained the complaints. A contemporary Los Angeles Times account found the researchers preparing to examine hearing itself. Kelly was interested in the possibility that the ear might generate or respond to a low-frequency sensation in a way the field instruments could not capture. That was a line of inquiry, not a diagnosis of the residents.

Two years later, Mullins and Kelly wrote that their interest remained high. They were developing equipment to test low-frequency hearing thresholds and possible emissions from the ear. They described intriguing informal testing of one hearer, but did not offer a completed explanation for the group. The sound had led them from bedroom breakers and distant fields to the fine workings of human hearing.

By then the Saltzmans had already made a different decision. In September 1993, the Los Angeles Times reported that they were selling their home and planning to leave the country. Instruments had produced records; the couple still lived with an experience those records could not locate. Taos had made the hum public, but publicity had not made it audible to everyone.

What Is Known

The case rests on two kinds of near-contemporary material. Newspaper interviews from 1993 preserve named residents’ descriptions, their reported attempts to find or escape the sound, and the response that led to a formal investigation. These are firsthand accounts as recorded by reporters, not measurements of a shared acoustic signal.

The strongest technical source is Mullins and Kelly’s 1995 article in Echoes, written by two members of the investigative team. It records the ten-person frequency-matching exercise, the custom microphone, field measurements and mailed survey. It is a retrospective summary of the 1993 work rather than the full underlying dataset. It establishes what the team tried and what it reported finding; it does not identify a single cause for all hearers.

The investigation found ordinary low-frequency background noise and electrical signals, but no measured external signal that followed the reported hum across sites. Eight hearers’ ability to match a generated tone shows they could describe their perception consistently in that test. It does not, by itself, show that the same tone existed in the surrounding air before the speaker was switched on.

The Bigger Picture

Taos sits at the boundary between two questions that are easy to collapse. One asks whether a person hears something. The other asks whether a particular external source makes it. The residents’ reports and the survey speak to the first; the microphone, geophones and electromagnetic instruments addressed the second. Neither kind of record can replace the other.

The U.S. National Institute on Deafness and Other Communication Disorders explains that a person can perceive a hum or other sound without an external source. This is one reason a negative microphone recording cannot mean an experience is imaginary. It also does not establish that the Taos hearers all had tinnitus. Mullins and Kelly were still testing low-frequency hearing when they published their account.

A 2016 questionnaire study of people reporting similar hums proposed that some experiences could arise within the hearing and balance system. Its participants were not the original Taos field-study group, and a questionnaire cannot retrospectively diagnose them. The wider research suggests more than one route by which a low hum might be perceived; the 1993 measurements did not reduce every Taos report to one route.

What remains most distinctive is how carefully the town tried to meet an elusive sound on both sides of that boundary. Residents turned off power, travelled away from home and asked neighbours. Investigators built a large microphone, followed an electrical lead into the countryside, listened for earth movement and tested the ear. For Walters, the hum had survived the switch at his breaker box. In the research record, it survived the switch from testimony to instruments, still heard by some and still without a common source the team could point to.