Image response, harmonic of the IF, direct IF response, harmonics of the oscillator, combination of the IF, heterodyne oscillator radiation, cross modulation within the receiver, cross modulation external to the receiver, same channel beat, adjacent channel beat and monkey chatter are all sources of radio interference addressed in this article that appeared in a 1946 edition of Radio News. I don't know about you, but I've never heard of the term 'monkey chatter.' According to the troubleshooting table it is, "Unintelligible modulation superimposed upon desired station, having the character of 'inverted speech'." Recommendations on how to mitigate 'monkey speech' are provided.
Analysis of Radio Interference Phenomena
Character, Cause, Type Receivers Affected, Where Prevalent, and Service Remedies
(Reprinted from February 1946 issue "RCA Radio Service News," Tube Department, Radio Corporation of America, Harrison, N.J.)
Posted March 31, 2015