Around the year 1900 Lord Rayleigh developed the duplex ( combination of two ) theory of human sound localization using two binaural cues, interaural phase difference ( IPD ) and interaural level difference ( ILD ) ( based on analysis of a spherical head with no external pinnae ).

The modern binaural stethoscope with two ear pieces was invented in 1851 by Arthur Leared.

The Rappaport-Sprague model stethoscope was heavy and short () with an antiquated appearance recognizable by their two large independent latex rubber tubes connecting an exposed-leaf-spring-joined-pair of opposing " f "- shaped chrome-plated brass binaural ear tubes with a dual-head chest piece.

A typical binaural recording unit has two high-fidelity microphones mounted in a dummy head, inset in ear-shaped molds to fully capture all of the audio frequency adjustments ( known as head-related transfer functions ( HRTFs ) in the psychoacoustic research community ) that happen naturally as sound wraps around the human head and is " shaped " by the form of the outer and inner ear.

Naturally, the expense of owning two radios was, at the time, too much for a broad audience, and again binaural faded into obscurity.

These experiments proved that for these sessions two separate microphones had been used, placed near each other and each leading to its own turntable, with binaural sound being the result when synchronised.

A head-related transfer function ( HRTF ) is a response that characterizes how an ear receives a sound from a point in space ; a pair of HRTFs for two ears can be used to synthesize a binaural sound that seems to come from a particular point in space.

Specifically, women seemed to experience two separate peaks in their ability to perceive binaural beats — peaks possibly correlating with specific points in the menstrual cycle, onset of menstruation and during the luteal phase.

This bi-coordinate sound localization is accomplished through two binaural cues: the interaural time difference ( ITD ) and the interaural level difference ( ILD ), also known as the interaural intensity difference ( IID ).

Such a stimulus is often aural, as in the case of binaural or monaural beats and isochronic tones, or else visual, as with a dreamachine, a combination of the two with a mind machine, or even electromagnetic radiation.

Unlike binaural and monaural beats, isochronic tones do not rely on the combination of two tones – the " beat " is created manually by turning a tone on and off.

Only two songs are in circulation from these recordings: " Steal Away " and " Operator ".

Many Haley discographies list two 1946 recordings by the Down Homers released on the Vogue Records label as featuring Haley.

Uncharacteristically, Jefferson's first two recordings from this session were gospel songs (" I Want to be like Jesus in my Heart " and " All I Want is that Pure Religion "), released under the name Deacon L. J. Bates.

He made two further disc recordings for Linguaphone in 1943 and 1956.

* A combination of two devices ( or only one, if playback is digital ) to play sound recordings, for alternating back and forth to create a continuous playback of music ( for example, record players, Compact Disc players, computer media players such as an MP3 player, etc.

Posthumously, two albums of demo recordings from 1974 to 1977 — Hardcore Devo: Volume One ( 1990 ) and Hardcore Devo: Volume Two ( 1991 )— were released on Rykodisc, as well as an album of early live recordings, DEVO Live: The Mongoloid Years.

On 10 October 2006 Sounds of the Season: The Enya Holiday Collection was released containing six songs: the previously released " Oíche Chiúin " ( a. k. a. " Silent Night ") and " Amid the Falling Snow ", new recordings of the standards " Adeste Fideles " ( a. k. a. " Oh Come All Ye Faithful ") and " We Wish You a Merry Christmas " as well as two original songs, " Christmas Secrets " and " The Magic of the Night ".

To help finance the fledgling band, two more Move albums were released during the lengthy ELO recordings.

Led Zeppelin Boxed Set 2 was released in 1993 ; the two box sets together containing all known studio recordings, as well as some rare live tracks.

Key recordings included Jefferson Airplane's Surrealistic Pillow, the first album to come out of San Francisco during this era, which sold well enough to bring the city's music scene to the attention of the record industry: from it they took two of the earliest psychedelic hit singles: " White Rabbit " ( 1967 ) and " Somebody to Love " ( 1967 ).

These recordings, made circa 1860, include fragments of two French songs and a recitation in Italian.

A change in angle, albeit small, will have a detrimental effect ( especially with stereo recordings ) by creating different forces on the two groove walls, as well as a slight timing shift between left / right channels.

Tape bias is the term for two phenomena, DC bias and AC bias, that improve the fidelity of analogue magnetic tape sound recordings.

The music would then be recorded by the two, along with other musicians – dubbed the Clangers ensemble – in a village hall, where they would often leave the windows open, leading to the sounds of birds outside being heard on some recordings.

The now-obsolete 3 / 4 " U-matic systems use a heterodyned ~ 688 kHz subcarrier for NTSC recordings ( as does Sony's Betamax, which is at its basis a 1 / 2 ″ consumer version of U-matic ), while PAL U-matic decks came in two mutually incompatible varieties, with different subcarrier frequencies, known as Hi-Band and Low-Band.

With these two recordings, especially, he helped to invent the jazz ballad style and hinted at what, in the 1950s, would become cool jazz.

The two reworked existing Conspiracy demos and recordings to turn them into Yes songs and added new material.

Piazzolla would lead Fiorentino's orchestra until 1946 and make many recordings with him, including his first two instrumental tangos, La chiflada and Color de rosa.

Briefly forming his own group, the Jazz Tango Quintet with whom he made just two recordings, his attempts to blend jazz and tango where not successful.

On May 14, 1923, while in New York City, Valentino made his only two vocal recordings for Brunswick Records ; " Kashmiri Song " ( The Sheik ) and " El Relicario " ( Blood and Sand ).

Later that same year, Psyche's history repeated itself when Gero Herrde from Synthetic Symphony / SPV requested that Psyche re-release their first two albums allowing for the chance to remaster the material, add historical early recordings, and update the design for the legendary " Insomnia Theatre " and " Unveiling The Secret " albums.

Welz later released a single overdubbing two Haley demo recordings using a group of session musicians who were dubbed The Comets for the occasion.

The Beach Boys are probably the best example of this trend-within two years of the band's commercial breakthrough, group leader Brian Wilson had taken over from his father Murry, and he was sole producer of all their recordings between 1963 and 1967.

Although Razaf's songs are found on hundreds of recordings, there are only two albums devoted exclusively to his compositions:

A company of cavalry couldn't come in there if two men were guarding that trail ''.

After the first two murders, the warning notes were rarely ignored.

There were two horses in the barn, a sway-backed dun and Jess Crouch's buckskin.

Four cars were parked at the curb, and two of them were police radio cars.

Her glance swung past the trailer where the two drivers were standing.

These two were going to be easy pickins.

In the past, the duties of the state, as Sir Henry Maine noted long ago, were only two in number: internal order and external security.

They were camped beside a large column-shaped boulder: a man, his lubra, and two children.

There were two rubbing sticks for making fire, two stones shaped roughly like knives, a woven-root container which held a few pounds of dried worms and the dead body of some rodent.

During his two terms the Constitution was tested and found workable, strong national policies were inaugurated, and the traditions and powers of the Presidential office firmly fixed.

But the fences were still in place fifty-odd years ago, and when we stood on the gate to look over, the sidewalk under our eyes was not cement but two rows of paving stones with grass between and on both sides.

The contributors to this testament were all well-known: a former Democratic candidate for President, a New Deal poet, the magazine's chief editorial writer, two newspaper columnists, head of a national broadcasting company, a popular Protestant evangelist, etc..

There never were two fames alike.

The sickness was gone and, after all, the two young couples were on their honeymoon.

On Sundays, with the permission of Captain Heard, who usually attended with two of his officers, services were held in the double cabin.

Somewhat daunted, the two American missionaries reached the police station where they were questioned by a most unfriendly clerk.

The last two were a red and a black chow.

Actually, two flags were used at the mansion -- a small one on rainy days, and a big one on bright days.

In his own state of New York, the two Democratic bellwethers, State Leader Hill and Tammany Boss Murphy, were saying nothing openly against Hearst but industriously boosting their own favorites, Murphy being for Cleveland and Hill for Parker.

Gaunt scaffoldings adjoined the ruins, and on the ground segments of columns two and a half to three feet in thickness were being fitted with sections cunningly chiseled to match exactly the fluting and proportion of the original.

There is a mediocre restaurant at Sounion and I fed a thin little Grecian cat and gave it two saucers of water -- there was no milk -- which it lapped up as though it were nectar.

When, in March, 1640, the two towns were united under Coddington, Gorton claimed the union was irregular and illegally constituted and that it had never been sanctioned by the majority of freeholders.

Consequently, Fred and Tom, the two who had been provided college educations, signed statements to the effect that each had received his bequest in full, and Effie and I were each allotted $5000.