Pandora Media (NYSE:P) might be pleased with its most recent results, but the stock's subsequent drop most definitely isn't music to investors' ears. Shares of the online music-streaming specialist plunged nearly 20% in Thursday's after-hours trading after it released weaker-than-expected fourth-quarter results.

Specifically, Pandora's fourth-quarter adjusted revenue climbed 33% year over year, to $268 million. Within that, advertising revenue rose 36%, to $220.1 million, including a 90% increase in local ad sales, to $49.9 million. Mobile revenue was also particularly strong, growing 43% year over year, to $209.5 million, to represent a full 78% of Pandora's total revenue. Pandora also stated mobile monetization "reached record highs across all dimensions of Pandora's business."

As a result, Pandora's adjusted earnings before interest, taxes, depreciation, and amortization rose 68% year over year, to $43.8 million. And adjusted net income rose to $0.18 per diluted share, up from $0.11 per diluted share in the same year-ago period.

Unfortunately, analysts were more optimistic on both fronts, with average estimates calling for slightly higher revenue, and earnings of $276.5 million and $0.19 per share, respectively.

To make matters worse, Pandora expects first-quarter revenue of $220 million to $225 million, with adjusted EBITDA expected to be a loss in the range of $35 million to $30 million. Analysts, on average, were looking for Q1 revenue of $243.6 million to result in a loss of $0.05 per share.

Finally, for the full year 2015, Pandora expects revenue of $1.15 billion to $1.17 billion, and adjusted EBITDA of $70 million to $80 million. Wall Street was modeling 2015 earnings of $0.51 per share on higher sales of $1.21 billion.

It wasn't all bad
To its credit, Pandora's quarterly miss wasn't that significant. But at least last quarter the company posted a solid beat on both the top and bottom lines.

However, note that Pandora stock also fell following last quarter's results, but only because of continued deceleration in year-over-year growth to 5.2% of its monthly active listener base. Ironically, this time, Pandora's active listeners rose a respectable 7% year over year, to 81.5 million, breaking its streak of decelerating growth, and bringing it ever closer to its long-term goal of exceeding 100 million monthly active listeners in the U.S.

But arguably even more important -- at least according to Pandora CEO Brian McAndrews -- is the loyalty of those listeners. Total listener hours continued to outpace growth in the number of actual listeners, increasing 15% year over year in the fourth quarter, to 5.2 billion -- another record high. Total hours per active listener also continued to grow, increasing 7% over the same year-ago period to 22 hours during the quarter. That Pandora achieved this feat is made all that much more impressive considering it simultaneously endured an onslaught of new competitors including Apple's iTunes Radio, Google Play Music, and Amazon's new Prime Music service.

Finally, based on both Pandora's estimates and third-party research from Edison, Pandora's share of U.S. radio listening increased from 8.6% in December of 2013 to 9.7% in December of 2014. While this transition is gradual, it still bodes well for Pandora over the long term as the roughly 250 million current total U.S. radio listeners continue to move away from traditional terrestrial-based stations.

In the end, Pandora simply couldn't live up to Wall Street's lofty expectations; but there's plenty to like about where the company stands today