Three-quarters of the way through 2008, there are signs of subtle shifts in the U.S. music industry, all of them pointing to a digital future.

Combined U.S. sales of albums and track-equivalent albums (or TEA, where 10 digital tracks equal an album) totaled 377.4 million units during the nine months ending Sept. 28, down 5.3% from 398.6 million units during the same period last year, according to Nielsen SoundScan.

That marked a steeper fall than the 4.7% year-on-year sales drop recorded during the first half of 2008, which was about half the 9.1% decline posted during the year-earlier period.

But year-to-date sales through Sept. 28 also represent a slower rate of decline compared with the first nine months of 2007, when sales fell 8.4% from 435 million units a year earlier.

Digital music sales continued to play a crucial role in staunching ongoing heavy losses in physical sales. Combined sales of digital albums and TEA totaled 126.8 million units, accounting for 33.6% of combined album and TEA sales, up from 24.3% from the same period last year.

As they have during the last two years, digital track sales slowed in the third quarter from the previous two quarters, totaling 253.1 million units, down from 261.3 million in the second quarter and 281.4 million in the first quarter. But year-on-year, digital-track sales growth remained robust, surging 30% during the quarter from 194.9 million a year earlier. Digital track sales during the first nine months of 2008 were also up 30% from a year earlier to 795.8 million.

Digital album sales jumped 32% to 47.3 million, accounting for 15.9% of total album sales, up from 10.6% during the same period last year.

But bring physical sales into the mix and the picture looks...

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