Paul McCartney and Subtle Signals Development Experience – OpLaunch » dx

When the Beatles performed on the Ed Sullivan Show on 9 February 1964, there was noise from screaming fans. During this performance, John, Paul, George, and Ringo had difficulty hearing each other. However, they delivered a great performance. How did they coordinate their musical efforts?
Requisites to Coordination
The requisites to coordination in that noisy environment included:

Individually, John, Paul, George, and Ringo were proficient musicians. They invested years developing their musical abilities.
As a group, the Beatles practiced together for years. They performed under a diverse set of conditions. They had experience in ideal performance conditions and challenging performance conditions.
Musically, they knew what to expect. They pre-selected songs for the performance that they had mastered. The arrangements were designed for live performance by four musicians. These arrangements were familiar.
They did not rely on a technology that they could not control. They did not have a sophisticated audio monitoring system. They did not have headphones or in-ear personal audio monitors.
They did not rely on delayed feedback from others involved in the production.

In part, the quality of the musical performance required using information accumulated in the past to influence the future. This can be called a feed forward approach. A feed forward approach benefits from the involvement of proficient practitioners. In a feed forward approach, training precedes performance.
In other contexts, a feed forward approach may be characterized by a control signal that is transmitted from a source to a destination.
Prominent Signals and Subtle Signals
During the performances in 1964, the crowd noise was a prominent signal. During the performances, there were valuable subtle signals.
In a noisy environment, these subtle signals correlated with specific parts of each song. They included:

Discernible sounds such as the crash of a cymbal or the rumble from the bass drum
Facial expressions of the other musicians including mouth movements
Movements of fingers, arms, and feet of the other musicians
Interactions with the environment such as instantaneous interaction of the performance and reactions from the crowd

(Based on remarks by Paul McCartney in “The Beatles: The Night that Changed America. CBS 9 February 2014)
The subtle signals provided feedback during the performances. Feedback is an approach that uses information about current results to influence operation in the present. Feedback modifies a system based on interim results. Feedback changes the system output. This approach may be referred to as closed-loop feedback.
Subtle signals should be incorporated judiciously. Considerations include:

Valuable subtle signals may not be available when they would be the most useful.
Valuable subtle signals may be overlooked by novices.
An individual musician may not have the capacity to discern valuable subtle signals from the spurious subtle signals. Stated another way, an individual may not know that a subtle signal is valuable when they detect it.
The value of amplifying a particular signal by a specific amount is assessed by the nature of the results and the interaction with the environment.

Incorporating the appropriate subtle signals enabled the Beatles to be proficient performers in environments with nearly overwhelming undesirable noise.
Camera Operators Coordinated Their Efforts
It was so noisy in the Ed Sullivan Theater during the Beatles’ performances that the camera operators could not hear the instructions from the program director. The camera operators were proficient individually. They formed a cohesive team. They framed every shot without being able to hear the coordinating instructions from the director. The next week, a decision was made to replace the open-ear headphones with over-the-ear headphones.
(Based on remarks by the production crew in “The Beatles: The Night that Changed America. CBS 9 February 2014)
Mismatches