Headphones

Based on Wikipedia: Headphones

In 1910, a Milwaukee audiophile and jazz musician named John C. Koss couldn't find headphones good enough for his needs. Eight years later, he produced the first stereo headphones the world had ever seen—transforming how humanity would listen to music forever.

But the story of headphones begins far earlier, in the clattering din of telephone switchboards during the late nineteenth century. When Alexander Graham Bell's invention connected the first homes in the 1870s, operators at telephone exchanges faced a persistent problem: their hands were needed to juggle wires and connections, yet they also needed to listen to incoming calls. The solution was elegantly simple—mount the receiver onto the head. A clamp held the telephone receiver next to the ear, freeing both hands for the complex task of connecting callers. This apparatus was called a headphone, though it was only a single earpiece in those earliest versions.

By the 1890s, the British company Electrophone developed a listening device with two earpieces that connected below the chin, held by a long rod. Subscribers could listen to live performances at theaters and opera houses across London through what were essentially massive earphones. Meanwhile, French engineer Ernest Mercadier patented a set of in-ear headphones in 1891—some of the first designs that would fit directly inside the ear canal.

The emergence of wireless telegraphy in the early twentieth century pushed headphone development further. Developers used telephone receivers as detectors for electrical signals in wireless receiving circuits. By 1902, innovators like Lee de Forest were using two jointly head-mounted telephone receivers to hear signals—these were called "head telephones" in singular form. By 1908, the term simplified simply to "head phones," and a year later the compound word headphones entered common usage.

One of the earliest manufacturers was Holtzer-Cabot Company in 1909, producing head receivers for telephone operators alongside standard home receivers. Nathaniel Baldwin became the first major supplier of headsets to the U.S. Navy, motivated by his inability to hear sermons during Sunday service—his prototype telephone headset in 1910 was tested by the navy and promptly ordered in quantities of 100. Wireless Specialty Apparatus Co., partnering with Baldwin Radio Company, set up a manufacturing facility in Utah to fulfill these orders.

These early headphones used moving iron drivers with either single-ended or balanced armatures. The common single-ended type used voice coils wound around permanent magnet poles, positioned close to a flexible steel diaphragm. Without damping, the frequency response had large resonance peaks—resulting in poor sound quality compared to modern standards. These models lacked padding and were notoriously uncomfortable for extended wear.

Impedance varied significantly: headphones used in telegraph and telephone work had 75 ohms impedance, while those used with early wireless radio had more turns of finer wire for increased sensitivity, reaching 1,000 to 2,000 ohms—suited for crystal sets and triode receivers. Some highly sensitive units, like those manufactured by Brandes around 1919, were commonly used for early radio work.

The Modern Era

The transistor radio changed everything when it commercially appeared in 1954 with the introduction of the Regency TR-1. This became the most popular audio device in history, transforming listening habits and allowing people to hear music anywhere. Smaller earbud-type earpieces, which plugged into the user's ear canal, were first developed for hearing aids but became widely used with these transistor radios.

The 3.5 mm radio and phone connector—the most commonly used in portable applications today—has been used since at least 1964, when the Sony EFM-117J transistor radio was released. Its popularity was reinforced by its use on the Walkman portable tape player in 1979.

How They Work

Headphones are electroacoustic transducers that convert electrical signals to corresponding sound. They're worn on or around the head over the user's ears, allowing private listening—in contrast to loudspeakers that emit sound into open air for anyone nearby.

Three main types dominate the market. Circumaural headphones wrap around the ear with a band over the top of the head holding the drivers in place. Supra-aural headphones sit over the ear with the same band mechanism. Earbuds or earpieces plug directly into the ear canal, and within this category, wireless versions using Bluetooth have become ubiquitous.

Bone conduction headphones represent a third category—they wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open to ambient sound. This makes them popular among athletes and cyclists who need to remain aware of their surroundings.

Connections and Uses

In telecommunications contexts, a headset combines headphones with a microphone for two-way communication. Headphones connect to signal sources—audio amplifiers, radios, CD players, portable media players, mobile phones, video game consoles, or electronic musical instruments—either directly via cord or using wireless technology like Bluetooth, DECT, or FM radio.

Wired headphones typically use either 1/4 inch (6.4 mm) or 1/8 inch (3.2 mm) phone jacks for connecting to audio sources. Wireless headphones receive audio signals by radio waves from source devices like cellphones and digital players using Bluetooth connectivity.

The "Walkman effect" began in the 1980s—headphones started appearing in public spaces like sidewalks, grocery stores, and public transit as personal listening became normalized. Today, headphones are used professionally by audio engineers mixing sound for live concerts or recordings, disc jockeys cueing up songs without audiences hearing, aircraft pilots, and call center employees.

Quality and Design

Headphones exhibit a range of audio reproduction quality. Headsets designed for telephone use typically cannot reproduce sound with the high fidelity of expensive units designed for music listening by audiophiles. The market spans from basic headsets to premium headphones costing thousands of dollars, with differences in driver technology, frequency response, impedance, and comfort.

From the switchboard operators of the 1880s to today's Bluetooth-connected earbuds, headphones have evolved from simple telephone accessories into essential personal audio technology—and the sound they're producing has improved dramatically over that century of innovation.