Monaural facts for kids

A diagram of monaural sound

Monaural sound (often called mono) is a type of sound that seems to come from just one place. Imagine a single speaker playing music – that's mono sound. This is different from stereophonic sound (or stereo), which uses two separate sound channels. Stereo sound makes it feel like sounds are coming from different directions, like from the left or right, because it uses two speakers.

With mono sound, even if you use many speakers or headphones, the same sound signal goes to all of them. This makes the sound appear to come from one central spot between the speakers. When recording mono music, engineers use many microphones, but they mix all the sounds together into one main signal. This single signal is then played back as if it's coming from one unified spot.

Today, stereo sound is much more common for entertainment. However, mono sound is still used for things like phone calls, walkie-talkies, and special listening loops for hearing aids. Most AM radio stations broadcast in mono, while FM radio stations usually broadcast in stereo. Some talk radio stations on FM choose to broadcast in mono because it can make their signal stronger and reach a wider area.

History of Mono Sound

For a long time, mono sound was the main way to record and play audio. Even though people tried to experiment with stereo sound in the late 1800s, almost all sound recordings were mono until the middle of the 20th century.

You would typically find mono sound on:

• Old phonograph cylinders.
• Gramophone records made before 1958, like the ones that played at 78 revolutions per minute (rpm).
• Most AM radio broadcasts.
• Some FM radio stations that play only spoken words or talk shows. They do this to make their signal cover a larger area.
• Background music services, like those played in stores or public places.

Some older music artists, like John Mellencamp, have chosen to record their music in mono on purpose. They do this to make it sound like older blues or folk records. Famous bands like The Beatles also had their early albums re-released in mono. This was because their original recordings were often mixed for mono sound, even if they were later made into stereo versions.

In the 1960s and 1970s, it was common to try and turn mono songs into "fake" stereo songs. But these often didn't sound very good. Some film directors, like Stanley Kubrick, also preferred their movie soundtracks to be in mono.

Mono LP records slowly stopped being made after the early 1970s in most places. However, in the 1960s, many albums were released in both mono and stereo versions. This was because many people still had mono record players. Today, these original mono records are often worth more to collectors because they are rarer and sometimes have slightly different mixes of the songs.

In recent years, many classic mono albums have been re-released. For example, The Beatles, Bob Dylan, and The Kinks have all had special box sets of their original mono recordings come out.

How Mono and Stereo Work Together

Sometimes, when people talk about "mono sound," they might mean that two stereo channels have been combined into one. This is also called "collapsed stereo." Some devices combine stereo sound into mono to save money on parts.

However, combining stereo channels into mono can sometimes make the sound muffled. This happens because certain sound waves can cancel each other out when mixed. In professional recording studios, engineers usually create a separate mono mix of a song. This helps avoid the sound problems that can happen when you just combine stereo channels.

Mirrored Mono

"Mirrored mono" is the opposite of combining stereo. This happens when a mono sound is played through both the left and right speakers of a stereo system. So, the same single sound is "mirrored" on both sides. For example, if you play an old mono cassette tape on a stereo tape player, the mono sound will come out of both your left and right speakers.

Switching Between Mono and Stereo

Many devices, like FM radios or some video games, let you switch between stereo and mono sound. When you choose mono, the device might combine the stereo channels into one. When you switch back to stereo, it will play the sound through both speakers as separate left and right channels. This feature can be helpful if you are using mono equipment, like a guitar amplifier, with a stereo source.

Some older TV/VCR players had stereo sound for the TV part but only mono sound for the VCR part. This was common for home VCRs back then.

See also

• Stereophonic sound
• Binaural recording