R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64 (64-bit)

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> library("tuneR")
> d <- list.files("Testfiles", pattern="\\.mp3$")
> garbage <- lapply(d, 
+     function(x) {
+         wav <- readMP3(file.path("Testfiles", x))
+         cat(x, "\n")
+         print(wav)
+         if(is(wav, "Wave")){
+             print(rev(wav@left)[1:10])
+             if(wav@stereo)
+                 print(rev(wav@right)[1:10])
+         } else {
+             print(wav@.Data[1:10,])
+         }
+     }
+ )
mp3_mono_170kBit.mp3 

Wave Object
	Number of Samples:      3456
	Duration (seconds):     0.08
	Samplingrate (Hertz):   44100
	Channels (Mono/Stereo): Mono
	PCM (integer format):   TRUE
	Bit (8/16/24/32/64):    16 

 [1]  -9509 -11462 -13372 -15229 -17025 -18755 -20410 -21984 -23473 -24868
mp3_stereo_298kBit.mp3 

Wave Object
	Number of Samples:      3456
	Duration (seconds):     0.08
	Samplingrate (Hertz):   44100
	Channels (Mono/Stereo): Stereo
	PCM (integer format):   TRUE
	Bit (8/16/24/32/64):    16 

 [1]  -9509 -11462 -13372 -15229 -17025 -18755 -20410 -21984 -23473 -24868
 [1]  -4817  -5835  -6848  -7853  -8852  -9841 -10820 -11788 -12745 -13691
> 
> proc.time()
   user  system elapsed 
   0.43    0.03    0.46