“While we’ve devoted substantial resources to developing these products and learned a lot along the way, we haven’t had the impact we hoped for,” Susan Wojcicki, a vice president for product management, wrote on a blog announcing the end of Audio Ads.

Ms. Wojcicki said Google would apply some of its radio advertising technologies to selling ads on online audio programs. She also said that Google would try to find jobs for most of the people involved in the radio ads program but that up to 40 people might be laid off. A Google spokesman declined to say how many people worked on the radio initiative.

The announcement on Thursday also highlighted Google’s efforts to cut costs and focus on fewer, more promising projects as its core search advertising business has slowed sharply during the recession.

Three weeks ago, Google ended its Print Ads program, which sold spots in newspapers. Only one of Google’s offline advertising initiatives survives  the more ambitious effort to sell TV ads. Ms. Wojcicki said Google would continue to invest in it.

While Google has had middling success so far in TV advertising, analysts say, the company is not likely to give up on the effort quickly, because the market is so large and the initiative could help YouTube, Google’s video site.