I did some ABX on sample Pet Shop Boys - In The Night I posted here and playing with ABR and lowpass 16000 Hz.
Lame v3.98.2 setting -V3 resulted in a 178kbps files and was easy to ABX:
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 4
2008/11/13 16:14:04
File A: F:\Temp\01 - Pet Shop Boys - In The Night.flac
File B: F:\Temp\01 - Pet Shop Boys - In The Night --398V3.mp3
16:14:04 : Test started.
16:14:19 : 01/01 50.0%
16:14:22 : 02/02 25.0%
16:14:25 : 03/03 12.5%
16:14:30 : 04/04 6.3%
16:14:34 : 05/05 3.1%
16:14:40 : 06/06 1.6%
16:14:45 : 07/07 0.8%
16:14:49 : 08/08 0.4%
16:14:58 : 09/09 0.2%
16:15:02 : 10/10 0.1%
16:15:07 : 11/11 0.0%
16:15:17 : 12/12 0.0%
16:15:33 : Test finished.
----------
Total: 12/12 (0.0%)
As the average song bitrate is 178kbps I encoded flac file with "--abr 178" which resulted in a 176kbps file. ABX results:
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 4
2008/11/13 16:26:43
File A: F:\Temp\01 - Pet Shop Boys - In The Night.flac
File B: F:\Temp\01 - Pet Shop Boys - In The Night --398ABR178.mp3
16:26:43 : Test started.
16:26:59 : 01/01 50.0%
16:27:04 : 02/02 25.0%
16:27:08 : 03/03 12.5%
16:27:14 : 04/04 6.3%
16:27:17 : 05/05 3.1%
16:27:24 : 06/06 1.6%
16:27:31 : 07/07 0.8%
16:27:41 : 08/08 0.4%
16:27:49 : 09/09 0.2%
16:28:00 : 10/10 0.1%
16:28:10 : 11/11 0.0%
16:28:18 : 12/12 0.0%
16:28:20 : Test finished.
----------
Total: 12/12 (0.0%)
Still no clean sound and therefore easy to ABX (a kind of warbling sound of the foreground synthesizer which start at around 2.2 secs).
Then I compared abr-encoded files with and without lowpass 16kHz:
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 4
2008/11/13 16:38:22
File A: F:\Temp\01 - Pet Shop Boys - In The Night --398ABR178.mp3
File B: F:\Temp\01 - Pet Shop Boys - In The Night --398ABR178lowpass16000.mp3
16:38:22 : Test started.
16:38:44 : 00/01 100.0%
16:39:31 : 01/02 75.0%
16:39:50 : 02/03 50.0%
16:40:04 : 03/04 31.3%
16:40:10 : 04/05 18.8%
16:40:19 : 05/06 10.9%
16:40:42 : 06/07 6.3%
16:40:49 : 07/08 3.5%
16:40:58 : 08/09 2.0%
16:41:11 : 09/10 1.1%
16:41:24 : 10/11 0.6%
16:41:35 : 11/12 0.3%
16:41:46 : 12/13 0.2%
16:42:18 : 13/14 0.1%
16:42:25 : 14/15 0.0%
16:42:35 : Test finished.
----------
Total: 14/15 (0.0%)
Clearly file B sounds better (less warbling). With lowpass 16000 average bitrate is also 176kbps.
As the lowpass encoded-file sounded better I compared it with the flac file:
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 4
2008/11/13 16:45:25
File A: F:\Temp\01 - Pet Shop Boys - In The Night.flac
File B: F:\Temp\01 - Pet Shop Boys - In The Night --398ABR178lowpass16000.mp3
16:45:25 : Test started.
16:45:45 : 01/01 50.0%
16:45:53 : 02/02 25.0%
16:46:06 : 03/03 12.5%
16:46:10 : 04/04 6.3%
16:46:18 : 05/05 3.1%
16:46:27 : 06/06 1.6%
16:46:40 : 07/07 0.8%
16:47:00 : 08/08 0.4%
16:47:07 : 09/09 0.2%
16:47:13 : 10/10 0.1%
16:47:22 : 11/11 0.0%
16:47:28 : 12/12 0.0%
16:47:37 : 13/13 0.0%
16:47:54 : 14/14 0.0%
16:47:56 : Test finished.
----------
Total: 14/14 (0.0%)
Still distinguishable.
I tried several times ABX-ing -V3 file against the --abr 178 (default parameters/no lowpass) file but could not distinguish them.
So for now on this sample I can conclude that an abr-encoding with a lowpass close to my hearing limit contributes to handling problematic spots and sounds also better than -V3 encoded file (with defaults).