(August 20 2001 Diameter Research Study on the Impact of Audio Ads)

The likelihood to use the advertiser's service increased the more one heard the ad by nearly 25% (frequency of 21+ exposures) and even after 15- 30 days had passed, by over 14%

Web users exposed to the audio ad were 10 percent more likely to be aware of the advertiser, 59 percent more likely to recall its slogan, and 14 percent more likely to choose the advertiser.

Advertising awareness and advertising tagline showed striking effects with increases of +64% and +60% respectively

Web users who heard the ad retained a greater brand awareness of the advertiser for up to a month. The ad's impact was greatest, at 11 percent, among people who had heard the ad within a week of being surveyed. But even among listeners who had last heard the ad 15-30 days before being surveyed, awareness of the advertiser was 9 percent higher than among users in the control group

Frequency of exposure increased impact on all brand metrics measured. The greatest increases were noted for advertising awareness (+118% after 21 or more exposures to the audio ad) and ad element recall (+195% after 21 or more exposures).