Fed.R.Evid. 103(d), expressly preserving the 'plain error' doctrine of Rule 52 of the Federal Rules of Criminal Procedure, provides: 'Nothing in this rule precludes taking notice of plain errors affecting substantial rights although they were not brought to the attention of the court.' It is generally true, of course, that 'otherwise inadmissible hearsay to which no objection has been lodged may be considered by the trier-of-fact to the extent of its probative value.' United States v. Leaman, 546 F.2d 148, 150 (5th Cir.), Cert. denied, 431 U.S. 917, 97 S. Ct. 2180, 53 L. Ed. 2d 227 (1977); Accord, Flores v. Estelle, 513 F.2d 764, 766 (5th Cir.), Cert. denied, 423 U.S. 989, 96 S. Ct. 401, 46 L. Ed. 2d 308 (1975); Smith v. United States, 343 F.2d 539, 542 (5th Cir.), Cert. denied, 382 U.S. 861, 86 S. Ct. 122, 15 L. Ed. 2d 99 (1965); Glenn v. United States, 271 F.2d 880, 883 (6th Cir. 1959).
Under certain unusual conditions, however, the admission of hearsay evidence to which an entirely satisfactory objection has not been made may require reversal of a criminal conviction if the admission of such evidence constitutes plain error ...